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9 Laboratory Facilities 9.A INTRODUCTION 213 9.B GENERAL LABORATORY DESIGN CONSIDERATIONS 213 9.B.1 Relationship Between Wet Laboratory Spaces and Other Spaces 213 9.B.1.1 Relationship Between Laboratory and Office Spaces 213 9.B.2 Open Laboratory Design 213 9.B.2.1 Considerations for Open Laboratory Design 213 9.B.3 Closed Laboratories and Access 214 9.B.4 Equivalent Linear Feet of Workspace 215 9.B.5 Laboratory Layout and Furnishing 215 9.B.5.1 Adaptability 215 9.B.5.2 Casework, Furnishings, and Fixtures 216 9.B.5.3 Shared Spaces 216 9.B.5.4 Flooring 216 9.B.5.5 Doors, Windows, and Walls 216 9.B.6 Noise and Vibration Issues 216 9.B.7 Safety Equipment and Utilities 217 9.B.8 Americans with Disability Act: Accessibility Issues Within the Laboratory 218 9.B.9 Older Facilities 218 9.C LABORATORY VENTILATION 219 9.C.1 Risk Assessment 219 9.C.2 Laboratory Chemical Hoods 221 9.C.2.1 Laboratory Chemical Hood Face Velocity 221 9.C.2.2 Factors That Affect Laboratory Chemical Hood Performance 222 9.C.2.3 Prevention of Intentional Release of Hazardous Substances into Chemical Hoods 222 9.C.2.4 Laboratory Chemical Hood Performance Checks 222 9.C.2.5 Housekeeping 223 9.C.2.6 Sash Operation 223 9.C.2.7 Constant Operation of Laboratory Chemical Hoods 224 9.C.2.8 Testing and Verification 224 9.C.2.9 Laboratory Chemical Hood Design and Construction 228 9.C.2.10 Laboratory Chemical Hood Configurations 231 9.C.2.11 Laboratory Chemical Hood Exhaust Treatment 234 9.C.3 Other Local Exhaust Systems 236 9.C.3.1 Elephant Trunks, Snorkels, or Extractors 237 9.C.3.2 Slot Hoods 237 9.C.3.3 Canopy Hoods 237 9.C.3.4 Downdraft Hoods 237 9.C.3.5 Clean Benches or Laminar Flow Hoods 239 9.C.3.6 Ventilated Balance Enclosures 239 9.C.3.7 Gas Cabinets 239 211
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212 PRUDENT PRACTICES IN THE LABORATORY 9.C.3.8 Flammable-Liquid Storage Cabinets 239 9.C.3.9 Benchtop Enclosers 240 9.C.4 General Laboratory Ventilation and Environmental Control Systems 240 9.C.4.1 Constant Air Volume (CAV) Systems 241 9.C.4.2 Variable Air Volume (VAV) Systems 241 9.C.5 Supply Systems 241 9.C.6 Exhaust Systems 241 9.C.6.1 Individual Laboratory Chemical Hood Fans 241 9.C.6.2 Manifolded (Common Header) Systems 241 9.C.6.3 Hybrid Exhaust Systems 242 9.C.6.4 Room Purge Systems 242 9.C.6.5 Exhaust Stacks 242 9.D ROOM PRESSURE CONTROL SYSTEMS 242 9.E SPECIAL SYSTEMS 243 9.E.1 Gloveboxes 243 9.E.2 Clean Rooms 243 9.E.2.1 Clean Room Classification 243 9.E.2.2 Clean Room Protocols 244 9.E.2.3 Laboratory Chemical Hoods and Laboratory Furniture in Clean Rooms 244 9.E.3 Environmental Rooms and Special Testing Laboratories 244 9.E.3.1 Alternatives to Environmental Rooms 245 9.E.4 Biological Safety Cabinets and Biosafety Facilities 245 9.E.4.1 Biosafety Cabinets 245 9.E.4.2 Using a Biosafety Cabinet for Biological Materials 247 9.E.5 Nanoparticles and Nanomaterials 247 9.E.6 Explosion-Proof Chemical Hoods 248 9.F MAINTENANCE OF VENTILATION SYSTEMS 248 9.G VENTILATION SYSTEM MANAGEMENT PROGRAM 249 9.G.1 Design Criteria 249 9.G.2 Training Program 249 9.G.3 Inspection and Maintenance 250 9.G.4 Goals Performance Measurement 250 9.G.5 Commissioning 250 9.H SAFETY AND SUSTAINABILITY 250 9.H.1 Low-Flow or High-Performance Laboratory Chemical Hoods 251 9.H.2 Automatic Sash Closers 251 9.H.3 Variable Air Volume (VAV) Systems with Setback Controls 252 9.H.4 Variable Air Volume Systems, Diversity Factors 252 9.H.5 Lower General Ventilation Rates 252 9.H.6 Laboratory Chemical Hood Alternatives 252 9.H.7 Retro-Commissioning 252 9.H.8 Components of Heating, Ventilation, and Air-Conditioning (HVAC) 252 9.H.9 How to Choose a Ventilation System 252 9.I LABORATORY DECOMMISSIONING 253 9.I.1 Assessment 253 9.I.2 Removal, Cleaning, and Decontamination 253 9.I.3 Clearance 254
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213 LABORATORY FACILITIES 9.A INTRODUCTION near the laboratory. The need for personnel safety, evolutionary technology allowing for computer-based Trained laboratory personnel must understand research and data monitoring outside of the laboratory, how chemical laboratory facilities operate. Given the as well as a desire to foster better interaction between chance, they should provide input to the laboratory researchers has driven the offices outside the labora- designers to ensure that the facilities meet the needs tory proper. of the functions of the laboratory. Laboratory person- Locating all offices outside the laboratory environ- nel need to understand the capabilities and limitations ment allows for a safer workspace where food can be of the ventilation systems, environmental controls, consumed, quiet work can be done, and more paper laboratory chemical hoods, and other exhaust devices and books can be stored. Locating the office zone very associated with such equipment and how to use them close to or adjacent to the laboratory for easy access and properly. To ensure safety and efficiency, the experi- communication is desirable. mental work should be viewed in the context of the Some laboratories have office spaces within research entire laboratory and its facilities. areas. In this design, it is best to have an obvious separation between the laboratory area and the office 9.B GENERAL LABORATORY area using partitions or, at a minimum, aisle space, but DESIGN CONSIDERATIONS preferably using a wall and a door that can be closed. Occupants should not have to walk through labora- 9.B.1 Relationship Between Wet tory areas to exit from their office space. Visitors and Laboratory Spaces and Other Spaces students should not have to walk through laboratories to get to researchers’ offices, because those persons do Modern laboratories, particularly in academia, often not have personal protective equipment (PPE). (See have contiguous spaces that include wet laboratories, Vignette 9.1.) computer laboratories, instruments, write-up spaces, office areas, and other spaces with varying degrees of chemical use and hazards. Maintaining a positive 9.B.2 Open Laboratory Design safety culture and at the same time meeting the safety Traditionally, laboratories were designed for in- and comfort needs of laboratory personnel are chal- dividual research groups with walls separating the lenging under these circumstances. laboratories and support spaces. Group sizes ranged from 2 to 10 people, and most groups were completely • Wherever possible, separate wet chemical areas or self-contained, each with its own equipment and facili- those with a higher degree of hazard from other ties (Figure 9.1). areas with a physical barrier, such as a wall, di- Since the 1990s, the trend has been for researchers to vider, or control device. The objective is to protect collaborate in a cross-disciplinary nature; chemists, bi- the computer laboratory or otherwise low-hazard ologists, physicists, engineers, and computer scientists area from the risk of the higher hazard, and thus work together on a common goal. At the same time, eliminate the need to use protective equipment in laboratory designers have moved to open multiple- the low hazard area. module laboratories that allow a wide variety of con- • When such areas cannot be physically separated, figurations for casework and equipment setups. These o r where the risk cannot be eliminated com- laboratories often support large or multiple teams and pletely, individuals working at the computer or are configured with relocatable furnishings. in the write-up area need to evaluate what level Even when not using a multidiscipline approach, of protection may be needed to control the risk many facilities have moved toward larger, more open of exposure to the hazards in the other areas. For laboratories with the belief that working in teams raises example, all individuals in a computer laboratory overall productivity, promote open communication, must wear eye protection if there is a risk of eye and facilitates resource sharing. Team sizes, in some injury from operations in a contiguous area. disciplines, have risen and are frequently as high as 12 to 20 individuals. 9.B.1.1 Relationship Between Laboratory and Office Spaces 9.B.2.1 Considerations for Open Laboratory Almost all laboratory personnel require both labora- Design tory and office support space. Their desire to be aware There are advantages and disadvantages to open of procedures and to have a constant presence in the laboratory design. laboratory usually demands that office space be located
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214 PRUDENT PRACTICES IN THE LABORATORY tory (e.g., the floor of the building, the type of VIGNETTE 9.1 research) because of chemical storage code limita- Appropriate use of personal tions for flammable and other materials; protective equipment • need for isolated spaces because of specific types in shared spaces of work being conducted, such as cell or tissue work where cross-contamination is an issue, use In both these incidents, the research labora- of certain radioactive materials, lasers, materi- tories contained writing spaces with computer als requiring special security measures, glass- workstations and desks that were separated washing facilities (see section 9.B.3 for more from the working part of the laboratory by only information); an aisle. • challenge of storing chemicals and supplies when In one laboratory, a person was holding a there is a lack of natural spaces created by walls 250-mL glass flask when it overpressurized and and other fixtures; burst, spraying shards of glass across the labora- • noise from people and equipment may be higher tory. Not only did the person holding the flask than in a closed laboratory; and receive multiple lacerations, but another person • inability of some researchers to work effectively not involved in the procedure, sitting 3 m away in an open laboratory environment. at a desk, was hit by flying glass and received lacerations that required sutures. Design teams should work with the research teams In another laboratory, a container of nitric acid to find solutions that accommodate the needs of the and methanol sitting in a chemical fume hood researchers as much as possible. A combination of overpressurized and burst, spraying shards of open laboratory spaces with smaller areas dedicated glass and nitric acid over every surface of the to special functions is often necessary. laboratory. A person sitting 3 m away at a desk received some nitric acid and glass on the labora- 9.B.3 Closed Laboratories and Access tory coat, but nowhere else. In both cases, the potential for eye injuries, Closed or separate laboratory spaces are often nec- chemical burns, and physical injury to a person essary for certain functions because of the nature of not involved in the experiment existed. Both in- the operation, equipment needs, or security concerns. cidents illustrate the importance of wearing eye These areas may or may not be separated with a door. protection and other protective equipment, as The need for a door and access control should be exam- appropriate, whenever a risk is present. ined carefully for code requirements, safety protocol, and containment concerns. The following issues should be considered: • Do the exits require doors by code? Advantages include • Must the corridor walls, doors, and frames be fire- rated by code? • visibility among researchers; • Is containment of spills or smoke an issue that • better communication and collaboration; demands doors? • easy to share resources, including equipment, • Is noise an issue that demands separation and space, and support staff; attenuation? • flexibility for future needs because of open floor • Does the need for room air pressure control neces- plan with adaptable furnishings; sitate a door closing the laboratory space off from • significant space savings compared with smaller, other areas? enclosed laboratories; and • Does the work present a hazard that requires that • cost savings (first building/renovation costs and access by untrained personnel be controlled? ongoing operating costs) compared with smaller, • Do some materials or equipment present a secu- enclosed laboratories. rity risk? • Do the materials require compliance with bio- Disadvantages and limitations include safety guidelines? • for large spaces, challenging to balance the venti- Examples of operations or activities that may require lation system; separation from the main laboratory are in Table 9.1. • limitations to the size or placement of the labora- The use of unusually hazardous materials may re-
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215 LABORATORY FACILITIES FIGURE 9.1 Open versus closed laboratory design. The top figure is an example of a typical closed laboratory design with Figure 9.1.eps four separate laboratories. The three walls separate the space and extend from floor to ceiling, with no shared spaces. The bot- bitmap tom figure is an example of an open laboratory in the same space. The wall extends from floor to ceiling but not from wall to wall (although in some designs, it could). Smaller working rooms with permanent or movable walls are set up for storage or activities that require closed spaces. quire a dedicated area for such work to most efficiently these should be large enough to provide each person manage security, safety, and environmental risk. with a minimum of 3 linear ft, but it could be 8 ft or more depending on the planned activities and type of chemistry. 9.B.4 Equivalent Linear Feet of Workspace Typical chemistry laboratories are designed to pro- When designing new laboratory spaces, consider vide from 28 to 30 ELF per person. Quality control, the equivalent linear feet (ELF) of work surface within biology, and analytical laboratories range from 20 to the laboratory. ELF can be divided into two catego- 28 ELF per person. Quality control and production ries: bench and equipment. Bench ELF is the required laboratories tend toward the low end of this range, length of benchtop on which instruments can be set whereas research laboratories are at or above the high and where preparatory work takes place, as well as the end of the range. This number includes the support length of laboratory chemical hoods. Equipment ELF space outside the laboratory that is needed. These val- includes the length of floor space for equipment that ues can vary widely and must be addressed carefully does not fit on a bench. Typically, every two laboratory for each project. personnel whose work mostly involves hazardous chemicals should have at least one chemical hood, and 9.B.5 Laboratory Layout and Furnishing 9.B.5.1 Adaptability Some Activities, Equipment, or TABLE 9.1 The frequency of change in laboratory use has made Materials That May Require Separation it desirable to provide furnishings and services that from the Main Laboratory can be moved and adapted quickly. Although some Autoclaves Animal Handling Areas services and surfaces will be fixed elements in any laboratory, such as sinks and chemical hoods, there are Darkrooms Electron microscopes several options available to meet the adaptable needs Glasswashing facilities High-powered lasers Some radioactive materials Tissue culture work for various types of research. Exceptionally toxic materials High-pressure equipment Current design practice is to locate fixed elements
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216 PRUDENT PRACTICES IN THE LABORATORY such as laboratory chemical hoods and sinks at the is centrally located near a laboratory, it can be walled perimeter of the laboratory, ensuring maximum mo- off to reduce noise. bility of interior equipment and furniture. Although The team needs to carefully address the need for fixed casework is common at the perimeters, moveable alarms on specific pieces of equipment such as freezers pieces are at the center to maximize flexibility. The cen- and incubators that contain valuable samples. tral parts of the laboratory are configured with sturdy Care must be taken, however, not to assume that mobile carts, adjustable tables, and equipment racks. sharing is always effective. There are certain pieces of Another trend for new laboratory buildings is to equipment that must be dedicated to specific users. design interstitial spaces between the floors and to have all the utilities above the ceiling. The interstitial 9.B.5.4 Flooring spaces are large enough to allow maintenance workers to access these utilities from above the ceiling for both Wet laboratories should have chemically resistant routine servicing and to move plumbing and other covered flooring. Sheet goods are usually preferable utilities as research demands change. to floor tiles, because floor tiles may loosen or degrade Where interstitial spaces are not possible, overhead over time, particularly near laboratory chemical hoods service carriers may be hung from the underside of and sinks. Rubberized materials or flooring with a the structural floor system. These service carriers may small amount of grit may be more slip-resistant, which have quick connects to various utilities, such as local is desirable in chemical laboratories. Coved flooring exhaust ventilation, computer cables, light fixtures, and that allows 4 to 8 in. of flooring material secured to the electrical outlets. wall to form a wall base is also desirable. Floors above areas with sensitive equipment, such as lasers, should be sealed to prevent leaks. 9.B.5.2 Casework, Furnishings, and Fixtures Casework should be durable and designed and 9.B.5.5 Doors, Windows, and Walls constructed in a way that provides for long-term use, reuse, and relocation. Some materials may not hold up Walls should be finished with material that is easy well to intensive chemistry or laboratory reconfigura- to clean and maintain. Fire code may require certain tion. Materials should be easy to clean and repair. For doors, frames, and walls to be fire-rated. clean rooms, polypropylene or stainless steel may be Doors should have view panels to prevent accidents preferable. caused by opening the door into a person on the other Work surfaces should be chemical resistant, smooth, side and to allow individuals to see into the laboratory and easy to clean. Benchwork areas should have knee in case of an accident or injury. Doors should open in space to allow for chairs near fixed instruments or for the direction of egress. procedures requiring prolonged operation. Laboratories should not have operable windows, Work areas, including computers, should incorpo- particularly if there are chemical hoods or other local rate ergonomic features, such as adjustability, task ventilation systems in the lab. lighting, and convenient equipment layout. Allow ad- equate space for ventilation and cooling of computers 9.B.6 Noise and Vibration Issues and other electronics. Handwashing sinks for particularly hazardous ma- Many laboratories utilize equipment that may emit terials may require elbow, foot, or electronic controls. significant noise, require a stable structural environ- Do not install more cupsinks than are needed. Un- ment, or both. During early planning stages, all equip- used sinks may develop dry traps that result in odor complaints. Examples of Equipment That Can TABLE 9.2 9.B.5.3 Shared Spaces Be Shared Between Researchers and Many facilities encourage sharing of some pieces of Research Groups equipment. Locating the equipment in a space that is Balances Centrifuges not defined as part of an individual’s work zone facili- Gas chromatographs High-performance liquid chromatographs tates sharing. Some examples of equipment that can be Ice machines Incubators shared are in Table 9.2. Mass spectrometers NMRs Ovens pH meters In an open laboratory setting, duplication of much of Refrigerators/freezers Weigh enclosures this equipment can be avoided. Often, if the equipment
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217 LABORATORY FACILITIES ment should be discussed regarding any unique noise hoods and other ventilation. There may be resistance or vibration sensitivity in order to locate the equipment to the idea of installing sprinkler systems in laborato- properly. ries, particularly laboratories that use water-sensitive Large equipment such as centrifuges, shakers, and chemicals or equipment. The following facts may be water baths often work best in separate equipment helpful: rooms. Pumps for older mass spectrometer units are both hot and noisy and are often located in either a • Each sprinkler head is individually and directly small room or a hall. If in a closet, the area must have activated by the heat of the fire, not by smoke or extra exhaust to remove heat, or else equipment may an alarm system. Thus, small fires are not likely fail from overheating. With smaller and newer mass to activate the sprinkler and moderate-size fires spectrometers, the pumps are often small and can fit will likely activate only one or two heads. Indeed, into cabinets specifically designed for them. These more than 95% of fires are extinguished by one or pumps work especially well when water cooling is two sprinkler heads. not required. Very few researchers need to hear their • Statistics show that the sprinkler head failure rate instrumentation running, but many want to see the is 1 in 16 million. equipment. • In the event that the water from the sprinkler Another consideration crucial to equipment- system reacts with water-sensitive materials, en- intensive areas is the allowable vibration tolerance. suing fires would be quenched once the reaction Most analytical equipment such as NMRs, sensitive stopped. Damage is likely to be less severe than microscopes, mass spectrometers, and equipment if a fire was not suppressed and was allowed to utilizing light amplification (laser) require either vi- reach other flammable or combustible materials bration isolation tables or an area that is structurally in the laboratory. designed to allow for very little vibration. Clarify the • Laboratory equipment, including lasers, is just tolerance requirements with the user and equipment as likely to be harmed by the fire as by the water. manufacturer during the equipment-programming Without the sprinkler system, a fire that is large phase, or early design process, so that the appropriate enough to activate the sprinkler system would structure can be designed and the construction cost can result in response by the fire department. The be estimated more accurately. sprinkler heads are designed to release water at a rate of 10–15 gallons per minute (gpm), whereas a firefighter’s hose delivers 250–500 gpm. 9.B.7 Safety Equipment and Utilities • Dry chemical systems can seriously damage elec- Each laboratory should have an adequate number tronic and other laboratory equipment and are and placement of safety showers, eyewash units, and impractical in a building-wide system. Alternative fire extinguishers for its operations. (See Chapter 6, agents are impractical because of the amount of section 6.C.10, for more information.) The American space required for the cylinders and are most ef- National Standards Institute (ANSI) Z358.1-2004 stan- fective in rooms or areas that are sealed, which is dard provides guidance for safety shower and eye- not how laboratories are designed. These systems wash installation. The 2004 version recommends pro- are most practical for an individual application, vision of tepid water, which can be complicated from such as a piece of equipment or a “sealed” room. an engineering standpoint. Although this standard • Locate utility shutoff switches outside or at the does not address wastewater, most designers agree exit of the laboratory. The purpose of the switch that emergency eyewash and shower units should be is to shut down potentially hazardous operations connected to drain piping. It is prudent to have floor quickly in the event of an emergency. drains near the units, preferably sloped to the drain to • Locate room purge buttons at the exits in labora- prevent excessive flooding and potential slip hazards. tories with chemical hoods. For most laboratory Consider choosing barrier-free safety showers and buildings, activating the room purge button shuts eyewash units that can accommodate individuals with down or minimizes supply air while increasing disabilities. The maximum reach height for the activa- exhaust ventilation. In the event of a chemical tion control for safety showers is 48 in. spill, activating the purge system will help venti- Sprinkler systems may be required by the building late the resulting chemical vapors more quickly. code and are almost always recommended. For areas • Laboratories should have abundant electrical with water-sensitive equipment or materials, consider supply outlets to eliminate the need for extension preaction systems. Most dry or alternative systems do cords and multiplug adapters. Place electrical not function in a laboratory environment with chemical panels in an accessible area not likely to be ob-
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218 PRUDENT PRACTICES IN THE LABORATORY structed. Install ground-fault circuit interrupters near sinks and wet areas. • Assess and provide for emergency power needs. • Where possible, install chilled water loops for equipment requiring cooling. Chilled water loops save energy, water, and sewer costs. 9.B.8 Americans with Disability Act: Accessibility Issues Within the Laboratory Title 1 of the Americans with Disabilities Act (ADA) of 1990 requires an employer to provide reasonable accommodation for qualified individuals with disabili- ties who are employees or applicants for employment, unless doing so would cause undue hardship. The de- sign team and the owner are responsible for identifying what reasonable accommodations should and can be made to meet ADA guidelines or requirements. In addition, some school systems and municipalities require a minimum number or percentage of accessible work areas in teaching laboratories. Accessible furni- ture, including laboratory chemical hoods, are readily available from most suppliers. The American Chemical Society has an excellent resource available online or in print, Teaching Chemistry to Students with Disabilities: A Manual for High Schools, Colleges, and Graduate Programs (ACS, 2001). It is prudent to provide barrier-free safety showers and eyewash units for all laboratories. Figure 9.2 il- lustrates the specifications for barrier-free emergency equipment, according to ANSI 117.1-1992, “Accessible and Usable Building Facilities.” Additional accommodations will likely need to be FIGURE 9.2 Specifications 9.2.eps Figure for barrier-free safety showers made individually, depending on the special needs of and eyewash units. bitmap the researcher. Partnering with the researcher, super- visor, and a laboratory safety professional will help determine the extent of the accommodations. For wet laboratories, service animals should either and maintains plumbing, ventilation, and structural have a place outside the lab or an area within the labo- components. Nonetheless, as individual laboratories ratory that is accessible without the animal having to or spaces are renovated for new uses or upgrades, traverse areas where chemicals or other hazardous ma- there are opportunities for improving and modernizing terials could be present at floor level, including spills. building systems. Depending on the location of the laboratory build- 9.B.9 Older Facilities ing, there may be requirements for bringing the entire building up to current building codes and standards Aging facilities can present multiple challenges. As once a certain percentage of the building is under materials of construction begin to degrade, the safety renovation. These code requirements may include fire and environmental provisions of the facility often de- protection systems, accessibility, plumbing, ventila- grade as well. Although some equipment and materials tion, alarm systems, chemical storage restrictions, and may continue to function well for many years, modern egress issues. alternatives may offer better safety and environmental With rising interest in energy conservation, there sustainability features. have been numerous studies and instances of retro- For older facilities, it is important to have a strong commissioning of laboratories. The focus is generally operations and maintenance program that monitors
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219 LABORATORY FACILITIES on the laboratory ventilation system, with the goal of systems are not used correctly or if they are bypassed, managing airflow and temperature control to eliminate the retro-commissioning efficiency may deteriorate. waste and reduce overall energy use. In “Laboratories for the 21st Century” the U.S. Environmental Protec- 9.C LABORATORY VENTILATION tion Agency (EPA/DOE, 2006), reports that in most studied cases, retro-commissioning, when planned and The laboratory ventilation system, whether it is the executed well, resulted in reductions of at least 30% of general ventilation, a chemical hood, or a specialized overall facility energy use with a payback period of exhaust system, is a critical means to control airborne less than 3 years. chemicals in the laboratory. The typical retro-commissioning process proceeds At a minimum, a well-designed laboratory ventila- in five major steps: tion system should include the following: 1. Planning. Bring facility and EHS staff, design • Heating and cooling should be adequate for the engineers, and users together to discuss goals. comfort of laboratory occupants and operation of Gather information about the current system, laboratory equipment. including the original plans, as-built plans, major • A differential should exist between the amount alterations, and current function, including ven- of air exhausted from the laboratory and the tilation rates. Develop the retro-commissioning amount supplied to the laboratory to maintain plan. a negative pressure between the laboratory and 2. Preinvestigation. Verify all systems including adjacent nonlaboratory spaces. This pressure dif- the direct digital control or building automation ferential prevents uncontrolled chemical vapors systems, evaluate all components that affect en- from leaving the laboratory. Clean rooms may ergy use, and verify monitoring systems. require a slightly positive pressure differential. 3. Investigation. Benchmark utility and energy use There should be separation between common data, analyze trends, and test all equipment. Test- spaces and the clean room to prevent migration ing should include functional testing of chemical of airborne contaminants. hoods and related components, including face • Exhaust ventilation devices should be appropriate velocity tests, containment tests, etc. to materials and operations in the laboratory. 4. Implementation. Select which improvements will be made and prioritize them. Implement the Many devices are used to control emissions of haz- improvements and test performance. ardous materials in the laboratory. A risk assessment 5. Handoff. Clearly document information and helps to determine the best choice for a particular op- provide training to laboratory personnel and eration or material (Table 9.3). maintenance personnel. NOTE: Clean benches are not designed for use with hazardous materials. These are appropriate for use in Common conditions that lead to energy waste work with materials that necessitate clean work condi- include tions and should only be used for materials or chemi- cals that one could safety use on a benchtop. • overabundance of laboratory chemical hoods, • l aboratory chemical hoods with large bypass 9.C.1 Risk Assessment openings, • dampers in fixed positions, For all materials, the objective is to keep airborne • overventilated laboratory spaces, concentrations below established exposure limits (see • excessive duct pressure, Chapter 4, section 4.C.2.1). Where there is no estab- • fans set to override position, lished exposure limit, where mixtures are present, • fans that are no longer operating efficiently, or where reactions may result in products that are • constant volume systems with no setback for tem- not completely characterized, prudent practice keeps perature or airflow when unoccupied, and exposures ALARA (as low as reasonably achievable). • high face velocities. For chemicals, determine whether the material is flammable or reactive or if it poses a health hazard from Whether retro-commissioning for energy efficiency inhalation. If no significant risk exists, the work does or for safety, ensure that all stakeholders are involved not likely require any special ventilation. If potential in the process. Once the work is complete, continue to risk does exist, look at the physical properties of the monitor efficiency and safety. It is important to include chemical, specifically its vapor pressure and vapor trained laboratory personnel in the feedback process. If density.
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220 PRUDENT PRACTICES IN THE LABORATORY TABLE 9.3 Laboratory Engineering Controls for Personal Protection Typical Number of Air Changes or Face Velocity in Linear Feet Type of Ventilation per Minute (fpm) as Appropriate Examples of Use • General laboratory 6–12 air changes/hour, Nonvolatile chemicals • ventilation depending on laboratory design Nonhazardous materials and system operation • Environmental 0 air changes Materials that require special environmental controls • rooms Nonhazardous amounts of flammable, toxic, or reactive chemicals. • Laboratory 10–15 air changes/minute or 60- Flammable, toxic, or reactive materials • chemical hoods 100 fpm depending on hood type Products or mixtures with uncharacterized hazards • Unventilated 0 air changes Flammable liquids • storage cabinets Corrosives • Moderately toxic chemicals • Highly toxic, hazardous, or odiferous chemicals (if equipped with flame Ventilated storage 1–2 air changes/minute cabinets arrestors) • Recirculating A1: 75 fpm Biological materials • biosafety cabinets A2: 100 fpm Nanoparticles, as of the date of publication • B1: 100 fpm Biological materials • Nanoparticles, as of the date of publication • Minute amounts of volatile chemicals • Total exhaust B2: 100 fpm Biological materials • biosafety cabinet Nanoparticles, as of the date of publication • Minute amounts of volatile chemicals • Glovebox Varies from no change to very Positive pressure for specialty environments • high rate of change, depending Negative pressure for highly toxic materials on the glovebox and the application • Downdraft table 150–250 fpm depending on Perfusions with paraformaldehyde, work with volatile, low to moderately design hazardous materials with higher vapor density where access from more than one side is necessary • Elephant trunk 150–200 fpm at opening Local ventilation of a tabletop • Discharge from equipment such as a gas chromatograph • Canopy N/A Ventilation of heat, steam, low or nontoxic materials with low vapor density • Ductless laboratory 10–15 air changes/minute Materials that are compatible with the filtration system, in controlled quantities chemical hood and under controlled conditions • Not suitable for particularly hazardous substances • Slot hood Varies with application Local ventilation of higher density materials at the source, such as an acid bath • Ventilated balance 5–10 air changes/minute Weighing and initial dissolution of highly toxic or potent materials enclosure • Benchtop ventilated Variable per the needs of the Benchtop equipment, such as rotovaps enclosures materials Vapor pressure is usually measured in millimeters material easily forms vapors and may require use of a of mercury. A low vapor pressure (<10 mmHg) indi- ventilated enclosure, such as a chemical hood. cates that the chemical does not readily form vapors Vapor density is compared to that of air, which is 1. at room temperature. General laboratory ventilation A chemical having a vapor density greater than 1 is or an alternative such as the elephant trunk or snorkel heavier than air. If the vapors need to be controlled, a may be appropriate, unless the material is heated or chemical hood or a ventilation device that draws air in a higher temperature room that might promote va- from below, such as a downdraft table or a slot hood por formation. High vapor pressure indicates that the or elephant trunk with the exhaust aimed low may be
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221 LABORATORY FACILITIES appropriate. Conversely, a chemical with a vapor den- A well-designed hood, when properly installed and sity less than 1 is lighter than air. Besides a chemical maintained, offers a substantial degree of protection to hood, a ventilation device that draws air from above, the user if it is used appropriately and its limitations such as an elephant trunk or snorkel with the exhaust are understood. Chemical hoods are the best choice, positioned above the source, may work best. particularly when mixtures or uncharacterized prod- For radioactive or biological materials, consider ucts are present and any time there is a need to manage whether the operations might cause the materials to chemicals using the ALARA principle. aerosolize or become airborne and whether inhala- tion poses a risk to health or the environment. De- 9.C.2.1 Laboratory Chemical Hood Face Velocity termine whether filtration or trapping is required or recommended. The average velocity of air drawn through the face For manipulating solid particulates, a chemical hood of the laboratory chemical hood is called the face ve- and similar equipment with higher airflow may be too locity. The face velocity greatly influences the ability to turbulent. Weighing boxes or ventilated balance enclo- contain hazardous substances, that is, its containment sures may be a better fit for such work. efficiency. Face velocities that are too low or too high For nanomaterials, a laboratory chemical hood might reduce the containment efficiency. be too turbulent for manipulating the materials. Also, Face velocity is only one indicator of hood perfor- consider whether the exhaust containing these tiny mance and one should not rely on it as a sole basis for particles should be filtered. Studies have shown that determining the containment ability of the chemical high-efficiency particulate air (HEPA) filters are very hood. There are no regulations that specify acceptable effective for nano-size particles. Containment tests for face velocity. Indeed, modern hood designs incorporate chemical hoods allow for a very minor amount of leak- interior configurations that affect the airflow patterns age into the breathing zone of the user. For chemical and are effective at different ranges of face velocity. vapors, such an amount may be insignificant, but in the For traditional chemical hoods, several professional same volume of nanoparticles, the number of particles organizations have recommended that the chemical may be quite large, and biosafety cabinets, gloveboxes hood maintain a face velocity between 80 and 100 feet or filtering hoods would be better. (See section 9.E.5 for per minute (fpm). Face velocities between 100 and 120 more information.) fpm have been recommended in the past for substances More specialized ventilation systems, such as bio- of very high toxicity or where outside influences ad- safety cabinets and gloveboxes, may be necessary to versely affect hood performance. However, energy control specific types of hazards, as discussed later in costs to operate the chemical hood are directly pro- this chapter. portional to the face velocity and there is no consistent evidence that the higher face velocity results in better containment. Face velocities approaching or exceeding 9.C.2 Laboratory Chemical Hoods 150 fpm should not be used; they may cause turbulence Laboratory chemical hoods are the most important around the periphery of the sash opening and actually components used to protect laboratory personnel reduce the capture efficiency, and may reentrain settled from exposure to hazardous chemicals and agents. particles into the air. Functionally, a standard chemical hood is a fire- and With the desire for more sustainable laboratory chemical-resistant enclosure with one opening (face) in ventilation design, manufacturers are producing high- the front with a movable window (sash) to allow user performance hoods, also known as low-flow hoods, access to the interior. Large volumes of air are drawn that achieve the same level of containment as tradi- through the face and out the top into an exhaust duct tional ones, but at a lower face velocity. These chemical to contain and remove contaminants from the labora- hoods are designed to operate at 60 or 80 fpm and in tory. Note that because a substantial amount of energy some cases even lower. (See section 9.C.220.127.116.11.) is required to supply tempered supply air to even a Average face velocity is determined by measuring small hood, the use of hoods to store bottles of toxic or individual points across the plane of the sash opening corrosive chemicals is a very wasteful practice, which and calculating their average. A more robust measure can seriously impair the effectiveness of the hood as a of containment uses tracer gases to provide quantita- local ventilation device. Thus, it is preferable to provide tive data and smoke testing to visualize airflow pat- separate vented cabinets for the storage of toxic or cor- terns. ASHRAE/ANSI 110 testing is an example of this rosive chemicals. The amount of air exhausted by such technique (see section 9.C.2.8 for more information). cabinets is much less than that exhausted by a properly This type of testing should be conducted at the time the operating hood. chemical hood is installed, when substantial changes are made to the ventilation system, including rebalanc-
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244 PRUDENT PRACTICES IN THE LABORATORY US FED STD 209E Clean Room Classification TABLE 9.4 Maximum Particles/ft3 ISO Class >0.1 μm >0.2 μm >0.3 μm >0.5 μm >5 μm Equivalent 1 35 7 3 1 – ISO 3 10 350 75 30 10 – ISO 4 100 – 750 300 100 – ISO 5 1,000 – – – 1,000 7 ISO 6 10,000 – – – 10,000 70 ISO 7 100,000 – – – 100,000 700 ISO 8 SOURCE : ANSI/IEST/ISO 14644-1:1999. most laboratories maintain negative airflow with re- 9.E.2.3 Laboratory Chemical Hoods and spect to adjacent nonlaboratory areas, clean rooms may Laboratory Furniture in Clean Rooms be slightly positive. Thus, it is important to ensure that Laboratory chemical hoods and laboratory furniture hazardous materials are stored in ventilated cabinets in clean rooms must be easy to clean and not subject and work with volatile hazardous materials is done to rust or chalking. Most prefer not to use materials with proper ventilation. with painted surfaces, which may chalk or peel over Depending on the clean room level, laboratory per- time, or wood products that may form wood dusts. sonnel may need to follow special protocols to mini- Stainless steel and thermoplastics are the most com- mize generation of particulates, including some or all mon materials. of the following: Polypropylene chemical hoods are commonplace in clean rooms. The main concern is that this material • Wear special clothing ranging from shoe covers- burns and melts very easily. In the event of a fire, a only to shoe covers and special laboratory coats to polypropylene chemical hood may become fully in- fully encapsulating bunny suits with head cover volved. For this reason, it is prudent to choose either a and beard cover. fire-retardant polypropylene or another thermoplastic • Use an air shower before entering the clean room. or to install an automatic fire extinguisher within the • Keep personal items out of the clean room. hood. • Use only specially made notebooks and paper in For nanomaterials, consider whether a chemical the clean room; no felt-tip pens (except permanent hood might be too turbulent for manipulating the ma- markers). terials. A biosafety cabinet, a ventilated enclosure with • Avoid bringing wood-pulp-based products into HEPA filtration, or a glovebox may be better alterna- the clean room, such as magazines, books, regular tives. (See section 9.E.5 for more information.) tissues, and regular paper. • Do not bring styrofoam or powders or any prod- ucts that may produce dusts or aerosols into the clean room. ISO Classification of Air Cleanliness for Clean Rooms TABLE 9.5 Maximum Particles/m3 FED STD 209E Class >0.1 μm >0.2 μm >0.3 μm >0.5 μm >1 μm >5 μm Equivalent ISO 1 10 2 — — — — ISO 2 100 24 10 4 — — ISO 3 1,000 237 102 35 8 — Class 1 ISO 4 10,000 23,700 1,020 352 83 — Class 10 ISO 5 100,000 237,000 10,200 3,520 832 29 Class 100 ISO 6 1,000,0000 — 102,000 35,200 8,320 293 Class 1000 ISO 7 — — — 352,000 83,200 2930 Class 10,000 ISO 8 — — — 3,520,000 832,000 29,300 Class 100,000 ISO 9 — — — 35,200,000 8,320,000 293,000 Room air SOURCE: ACGIH (1998). Copyright 1998. Reprinted with permission.
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245 LABORATORY FACILITIES 9.E.3 Environmental Rooms and Special Testing Laboratories BOX 9.2 Quick Guide for Working Environmental rooms, either refrigeration cold in Environmental Rooms rooms or warm rooms, for growth of organisms and cells, are designed and built to be closed air circulation Mold growth can cause problems for an experiment and systems. Thus, the release of any toxic substance into affect personnel health. To avoid mold: these rooms poses potential dangers. Their contained • eport any leaks or condensation to maintenance R atmosphere creates significant potential for the forma- personnel for repair. tion of aerosols and for cross-contamination of research • lean up spills immediately. Mold thrives on or- C projects. Control for these problems by preventing the ganic material. release of aerosols or gases into the room. Special ven- • o not keep papers or cardboard in the room. If D tilation systems can be designed, but they will almost such materials are needed, keep them in plastic always degrade the temperature and humidity stabil- bags. ity of the room. Special environmentally controlled • o not use wood. Replace wood shelving with D cabinets are available to condition or store smaller plastic or metal. quantities of materials at a much lower cost than in an • lean all surfaces with a hospital-grade disinfectant. C environmental room. Because environmental rooms have contained atmo- Be wary of using flammable materials in this room: spheres, personnel who work inside them must be able • here may be sources of ignition in the room, T to escape rapidly. Doors for these rooms should have including fan motors. magnetic latches (preferable) or breakaway handles • o not store flammable liquids in the room. D to allow easy escape. These rooms should have emer- gency lighting so that a person will not be confined in Ventilation is limited: the dark if the main power fails. Because these rooms • hemical vapors may accumulate. Do not use ma- C are often missed when evaluating building alarm sys- terials that require local ventilation. Even materials tems, be sure that the fire alarm or other alarm systems that normally may be used on a benchtop may are audible and/or visible from inside the room. pose a risk in a closed environment. Do a full risk As is the case for other refrigerators, do not use vola- assessment. tile flammable solvents in cold rooms (see Chapter 7, • imit the use of compressed gases in the event that L section 7.C.3). The exposed motors for the circulation they may displace oxygen and cause an oxygen- fans can serve as a source of ignition and initiate an deficient atmosphere. explosion. • o not store dry ice or liquid nitrogen in an en- D Avoid the use of volatile acids in these rooms, vironmental room, because sublimation of the because such acids can corrode the cooling coils in carbon dioxide may displace the air in the room, the refrigeration system, which can lead to leaks of creating an asphyxiation hazard. refrigerants. Also avoid other asphyxiants such as nitrogen gas in enclosed spaces. Oxygen monitors and Do not store foods in an environmental room: flammable gas detectors are recommended when the • o not store alcoholic or nonalcoholic beverages. D possibility of a low oxygen or flammable atmosphere • oods may absorb chemical vapors. Do not store F exists in the room. any food in these rooms. Box 9.2 provides some basic guidelines for working in environmental rooms. 9.E.3.1 Alternatives to Environmental Rooms may be used as incubators or for cooling, giving a full Shaker boxes may be a viable alternative to envi- range of options. ronmental rooms. These boxes come in a variety of shapes and sizes and may be stackable. They use less electricity, take up much less space, and have just as 9.E.4 Biological Safety Cabinets and much control over the environment. Biosafety Facilities A shaker box is a sealed cabinet with a pull-out work BSCs are common containment and protection surface. The user may control the environment within devices used in laboratories working with biologi- the cabinet, including the temperature, humidity, car- cal agents. BSCs and other facilities in which viable bon dioxide level, lighting, and vibration. Shaker boxes
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246 PRUDENT PRACTICES IN THE LABORATORY organisms are handled require special construction hazards: Selection, Installation, and Use of Biological Safety and operating procedures to protect laboratory per- Cabinets (HHS/CDC/NIH, 2007b). sonnel and the environment. Conventional chemical hoods should never be used to contain biological • A Class I biosafety cabinet does not provide a hazards. Biosafety in Microbiological and Biomedical Labo- clean work environment but does provide some ratories (HHS/CDC/NIH, 2007a), Primary Containment protection to the user. Like a chemical hood, it draws air through the face of the cabinet away for Biohazards: Selection, Installation, and Use of Biological Safety Cabinets ((HHS/CDC/NIH, 2007b), and Biosafety from the user, across the work surface, through a set of HEPA filters, and back into the laboratory. in the Laboratory: Prudent Practices for the Handling and Disposal of Infectious Materials (NRC, 1989) give detailed • A Class II biosafety cabinet (Type A1, A2, B1, information on this subject. or B2) provides a clean work environment and protection to the user. Internal supply air passes through a HEPA filter in a downward laminar 9.E.4.1 Biosafety Cabinets flow across the work surface, preventing cross- A biosafety cabinet is specially designed and con- contamination. It works by drawing room air structed to offer protection to the laboratory person- around laboratory personnel through slots in the nel and clean filtered air to the materials within the work surface at the front of the cabinet, offering workspace. A biosafety cabinet may also be effective user protection. Air also is exhausted through a for controlling nanoparticles. grill along the back of the cabinet and is either The three classes of biosafety cabinets for work with recirculated through HEPA filters to the internal biological agents are briefly described below. For more workspace or passes through another set of filters information, see the guide Primary Containment for Bio- to be exhausted to the room or through ductwork and out of the building. (See Figure 9.13.) HEPA Filter Room Air Potentially Contaminated HEPA Filtered Slots or Grill Fan FIGURE 9.13 Example of a Class II biosafety cabinet. Room air passes around the user through the grill at the front of the cabinet. Filtered air passes into the cabinet over the materials, 9.13.eps a clean environment for the materials in the cabinet. Figure providing Potentially contaminated air moves through the grill and slots, across the cabinet, and passes through HEPA filters.
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247 LABORATORY FACILITIES • A Class III biosafety cabinet provides maximum • Turn the cabinet on at least 10–l5 minutes prior protection to laboratory personnel and the work- to use, if the cabinet is not left running. Verify ing environment. This type of cabinet is a glove- the cabinet is operating properly and has been box with HEPA filter exhaust. certified within the dates recommended by your institution. A biosafety cabinet is generally not suited for work • Disinfect work surface with 70% alcohol or other with hazardous chemicals. Most biosafety cabinets ex- suitable disinfectant. haust the contaminated air through HEPA filters back • Place items into the cabinet so that they can be into the laboratory. This type of filter will not contain w orked with efficiently without unnecessary most hazardous materials, particularly gases, fumes, disruption of the airflow, working with materials or vapors. Even when connected to the laboratory from the clean to the dirty side. exhaust system, a ducted biosafety cabinet may not • Wear appropriate PPE. At a minimum, this will provide enough containment for work with hazard- include a buttoned laboratory coat and gloves. ous chemicals. For field testing of biosafety cabinets, • Adjust the working height of the stool or stand so consult NSF/ANSI Standard 49-2009. that the worker’s face is above the front opening. Some Class II biosafety cabinets may be connected • Delay manipulation of materials for approxi- to the laboratory exhaust system and may be touted mately 1 minute after placing the hands/arms as a combination biosafety cabinet and chemical hood. inside the cabinet. However, even when ducted, a biosafety cabinet may • Minimize the frequency of moving hands in and not provide adequate containment for work with haz- out of the cabinet. ardous materials. • Do not disturb the airflow by covering any of the Table 9.6 provides an overview of the characteristics grill or slots with materials. of different types of biosafety cabinets. • Work at a moderate pace to prevent airflow dis- ruption that occurs with rapid movements. • Wipe the bottom and sides of the cabinet surfaces 9.E.4.2 Using a Biosafety Cabinet for Biological with disinfectant when work is completed. Materials The following protocol should be followed when Unlike a chemical hood, a biosafety cabinet con- using a biosafety cabinet for work with biological tains filters that must be changed on a regular basis. materials: The biosafety cabinet must be decontaminated before replacing the filters and then recertified for use. Check Comparison of Biosafety Cabinet Characteristics TABLE 9.6 Applications Nonvolatile Toxic BSC Face Chemicals and Volatile Toxic Chemicals Class Velocity Airflow Pattern Radionuclides and Radionuclides I 75 In at front through HEPA to the outside or into the room through Yes When exhausted outdoorsa,b HEPA II, A1 75 70% recirculated to the cabinet work area through HEPA; 30% balance Yes (minute amounts) No can be exhausted through HEPA back into the room or to outside through a canopy unit; plenums are under negative pressure Yes (minute amounts)a,b II, B1 100 30% recirculated, 70% exhausted; exhaust cabinet air must pass Yes through a dedicated duct to the outside through a HEPA filter Yes (small amounts)a,b II, B2 100 No recirculation; total exhaust to the outside through a HEPA filter Yes II, A2 100 Similar to II, A1, but has 100 fpm intake air velocity and plenums are Yes When exhausted under negative pressure to room; exhaust air can be ducted to outside outdoors (formerly “B3”) (minute amounts)a,b through a canopy unit Yes (small amounts)a,b III N/A Supply air is HEPA filtered; exhaust air passes through two HEPA Yes filters in series and is exhausted to the outside via a hard connection aInstallation may require a special duct to the outside, an in-line charcoal filter, and a sparkproof (explosion-proof) motor and other electrical components in the cabinet. Discharge of a Class I or Class II, Type A2 cabinet into a room should not occur if volatile chemicals are used. bIn no instance should the chemical concentration approach the lower explosion limits of the compounds. SOURCE: HHS/CDC/NIH (2007b); NSF/ANSI Standard 49-2009.
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248 PRUDENT PRACTICES IN THE LABORATORY with your institutional biosafety officer for required • A low-flow enclosure or chemical hood equipped frequency. with a HEPA filter on the exhaust side is effective at reducing turbulence, preventing nanomaterials from being released into the environment through 9.E.5 Nanoparticles and Nanomaterials the exhaust system, and providing good con- Engineering control techniques such as source en- tainment for both nanomaterials and hazardous closure (i.e., isolating the generation source from the chemicals. For laboratories that can only provide worker) and local exhaust ventilation systems should one type of containment, this is a good alternative. be effective for capturing airborne nanomaterials, • A negative-pressure glovebox is effective. based on what is known of nanomaterial motion and • Class I biosafety cabinets that exhaust air through behavior in air. HEPA filters into the room or those that are hard- Though traditional chemical hoods may be used for ducted to the outdoors may provide good contain- research on nanoscale particles and materials, some ment for nanoparticles. Class II biosafety cabinets researchers find it challenging to work with nanopar- that exhaust air through HEPA filters back into ticles in hoods operating with a 100-fpm face velocity the room or those that are hard-ducted to the out- because of turbulent airflow. In addition, limited stud- doors may be a good choice. A glovebox provides ies demonstrate that chemical hoods that operate at a a high level of protection and can be equipped 100-fpm face velocity, even those that pass the ANSI/ with HEPA filtration. ASRAE containment tests, may allow nanoparticles to escape in quantities that may pose a risk to health or Some vendors have produced other alternatives, the environment (Ellenbecker and Tsai, 2008). This is most of which are Class I biosafety cabinets equipped similar to the experience of pharmaceutical companies with an ionizer near the front edge. handling dry powder formulations research. Lower- For laboratories with both hazardous chemicals flow, reduced-turbulence hoods may be warranted. and nanoparticle work, one strategy is to handle the Even at lower face velocities, dispersion of particles nanoparticles in a Class I or II biosafety cabinet or a may result in loss of materials or contamination of low-flow enclosure (see above), transfer the particles surfaces or both. This active area of research should be into solution, and then continue work in a laboratory carefully monitored by anyone working with nanopar- chemical hood. ticles in a laboratory. Do not use horizontal laminar-flow hoods (clean Because the effect of nanomaterials on the environ- benches) that direct a flow of HEPA-filtered air into ment is still a topic of research and debate, prudent the user’s face for any operations involving hazardous practice ensures that they do not disperse into the materials or engineered nanomaterials. environment through the ventilation system. HEPA filters, which are 99.99% efficient at removing 0.3-μm 9.E.6 Explosion-Proof Chemical Hoods and larger particles, are also very effective in trapping nanoscale particles. Some vendors offer ULPA filters, For operations involving materials that could ex- which are 99.9995% efficient at removing 0.12-μm plode, protection aimed at preventing ignition and and larger particles. Although ULPA filters are more containing an explosion may be necessary. The sash efficient than HEPA filters, HEPA filters are generally should be composed of a composite material of safety acceptable for nanoparticle work. HEPA filters should glass backed by polycarbonate, with the safety glass on be properly seated in well-designed filter housings. the interior side of the sash. In addition, all components Ionizers that are placed in either a chemical hood of the hood, including the electrical supply, lighting, or a cabinet or are integrated into a cabinet can help etc., must be explosion-proof. minimize dispersion of nanomaterials, reducing loss of materials and keeping the work surfaces cleaner. 9.F MAINTENANCE OF Exercise caution working with explosive or highly VENTILATION SYSTEMS flammable chemicals near an ionizer. Stainless steel is much easier to clean and may show Even the best-engineered and most carefully in- areas where materials have dispersed. Enclosures with stalled ventilation system requires routine mainte- stainless steel work surfaces are good for nanomaterial nance. Blocked or plugged air intakes and exhausts, as work but are not necessary. well as control system calibration and operation, alter There are several alternatives for controlling nano- the performance of the total ventilation system. Filters materials in the laboratory, and many ventilation ven- become loaded, belts loosen, bearings require lubrica- dors are working on systems specifically designed for tion, motors need attention, ducts corrode, and minor nanoparticles. components fail. These malfunctions, individually or
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249 LABORATORY FACILITIES collectively, affect overall ventilation performance. problems are suspected or when decisions on appro- Some laboratory ventilation systems have become so priate changes to a ventilation system are needed to complex that prudent practice requires a special team achieve a proper balance of supply and exhaust air. of facilities staff dedicated to the maintenance of the All ventilation systems should have a device that system. readily permits the user to monitor whether the total Inspect and maintain facility-related environmental system and its essential components are functioning controls and safety systems, including chemical hoods properly. Manometer, pressure gauges, and other de- and room pressure controls, fire and smoke alarms, vices that measure the static pressure in the air ducts and special alarms and monitors for gases, on a regular are sometimes used to reduce the need to manually basis. measure airflow. Determine the need for and the type Evaluate each laboratory periodically for the quality of monitoring device on a case-by-case basis. If the and quantity of its general ventilation and anytime a substance of interest has excellent warning properties change is made, either to the general ventilation system and the consequence of overexposure is minimal, the for the building or to some aspect of local ventilation system will need less stringent control than if the sub- within the laboratory. The size of a room and its geom- stance is highly toxic or has poor warning properties. etry, coupled with the velocity and volume of supply air, determine its air patterns. Airflow paths into and 9.G VENTILATION SYSTEM within a room can be determined by observing smoke MANAGEMENT PROGRAM patterns. Convenient sources of smoke for this purpose are the commercial smoke tubes available from local The laboratory ventilation system is one of the most safety and laboratory supply companies. If the general important aspects of laboratory safety and, at the same laboratory ventilation is satisfactory, the movement time, is likely to be the highest consumer of energy of supply air from corridors and other diffusers into in the laboratory building. Managing all facets of the the laboratory and out through laboratory chemical ventilation system is crucial to maximize safety and hoods and other exhaust sources should be relatively energy conservation. uniform. There should be no areas where air remains The AIHA/ANSI Z9.5-2003 Laboratory Ventilation static or areas that have unusually high airflow veloci- Standard provides an outline for a ventilation manage- ties. If stagnant areas are found, consult a ventilation ment program and recommends appointing a respon- engineer, and make appropriate changes to supply or sible person to oversee the program. The Leadership exhaust sources to correct the deficiencies. in Energy and Environmental Design (LEED) Green The number of air changes per hour within a labo- Building Rating System™ of the U.S. Green Building ratory can be estimated by dividing the total volume Council uses this model as a consideration in its certi- of the laboratory (in cubic feet) by the rate at which fication system for rating laboratory buildings. exhaust air is removed (in cubic feet per minute) and Overall, there are four main aspects of a ventilation multiplying the total by 60. For each exhaust port (e.g., system management program: design criteria, training laboratory chemical hoods), the product of the face area for laboratory personnel, system maintenance, and (in square feet) and the average face velocity (in linear performance measurement. feet per minute) gives the exhaust rate for that source (in cubic feet per minute). The sum of these rates for 9.G.1 Design Criteria all exhaust sources yields the total rate at which air is exhausted from the laboratory. The rate at which air is The institution should determine the criteria to use exhausted from the laboratory should equal the rate for all new installations of chemical hoods and other at which supply air is introduced into the room. Thus, ventilation systems. This might include decreasing the flow rate of supply air (perhaps to con- serve energy) decreases the number of air changes per • testing criteria as installed (e.g., all or a rep - hour in the laboratory, the face velocities of the chemi- resentative sampling of the hoods must pass cal hoods, and the capture velocities of all other local ANSI/ASHRAE 110-1995 containment testing as ventilation systems. installed); Airflows are usually measured with thermal an- • chemical hood design criteria (e.g., face velocity emometers or velometers. These instruments are criteria at specific sash height and sash design); available from safety supply companies or laboratory • types of continuous monitoring systems preferred supply houses. The proper calibration and use of or required (e.g., face velocity reading, magnehe- these instruments and the evaluation of the data are lic gauge); a separate discipline. Consult an industrial hygienist • acceptable diversity factors; or a ventilation engineer whenever serious ventilation • energy conservation strategies;
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250 PRUDENT PRACTICES IN THE LABORATORY • alarm systems; • type of duct work; • noise criteria; • preference for VAV systems (designing one extra fan into each system); and • backup power. 9.G.2 Training Program No matter how well a system is designed or main- tained, no matter what lengths an institution has gone to for the sake of safety and energy conservation, if laboratory personnel do not use the equipment prop- erly, individual users can defeat these efforts with their own behaviors. FIGURE 9.14 Examples of postings for laboratory chemi- Laboratory personnel who insist on working at the cal hoods. Clockwise from top left: reminder to close the edge of the laboratory chemical hood, raise the sash chemical hood sash, guide to checking the telltale ribbon above its maximum operating height, defeat alarms, taped to the sash of the chemical hood, reminder that a clean disable sash closures, do not move an elephant trunk bench is not for hazardous chemicals, indicator showing the close to the source, block baffles, use loose materials safe maximum sash height. in the chemical hood and clog the ductwork, leave the sash open when not working at the chemical hood, fail to report that a filter needs to be changed reduce safety 9.G.3 Inspection and Maintenance and sustainability efforts. Sometimes, these actions are Maintenance is key to a ventilation system man- due to lack of consideration; sometimes personnel may agement program. The program should describe the simply not understand the implications. elements of the inspection and maintenance program, All laboratory personnel should receive training that including includes • designation of who conducts inspections and how • how to use the ventilation equipment, often; • consequences of improper use, • how inspections are recorded; • what to do in the event of system failure, • inspection criteria for laboratory chemical hoods • what to do in the event of a power outage, including • special considerations or rules for the equipment, face velocity testing—equipment used, history, • significance of signage and postings. how recorded, how posted on the chemical hood, and Training may be one-on-one, classroom, Web-based, will maximum sash height be marked and how; or whatever format fits the culture of the institution • criteria for working on roofs and around stacks; and the needs of the laboratory. • fan maintenance schedule; Many laboratories, particularly academic research • VAV system maintenance schedule; laboratories, experience high turnover rates. Good • alarms and controls maintenance schedule; and signage and postings complement training and act as • schedule for recommissioning the ventilation constant reminders (Figure 9.14). system. Consider the following types of signs and postings: • sash position for laboratory chemical hoods, 9.G.4 Goals Performance Measurement • telltales (ribbons or similar materials on chemical The old adage that “you can’t manage what you hood sashes with a key to good performance), don’t measure” rings true too with the ventilation • meaning of any audible or visual alarms, management program. At least annually, evaluate the • function of occupancy sensors (e.g., setback mode effectiveness of the program, including tied to light switch), • downtimes if the system has a setback mode that • energy use and savings, is on a timer, and • emission issues, • reminder to lower the sash when not in active use.
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251 LABORATORY FACILITIES • trends in chemical hood performance (signs of deterioration, etc.), and • review of the life cycle of the ventilation system. 9.G.5 Commissioning When a new ventilation system in installed, new components are installed, or any significant change to the ventilation system occurs, consider hiring a commissioning agent with experience with laboratory facilities. An outside commissioning agent will ensure that the system meets the criteria you have selected, note any design errors, handle problems, and facilitate testing, installation, etc. In-house staff or hired consul- tants will continue to maintain the equipment, but the startup issues can be overwhelming. Ensure that those who will be using and maintaining the system receive Carbon inventory of a research university FIGURE 9.15 training. campus. research, and investigating ways to reduce the energy 9.H SAFETY AND SUSTAINABILITY needs of the building. Cost considerations should never take precedence over ensuring that laboratory personnel are protected 9.H.1 Low-Flow or High-Performance from hazardous concentrations of airborne toxic sub- Laboratory Chemical Hoods stances. That sentiment bears repeating. However, since the 1980s, the chemical hood has become a fixture Low-flow or high-performance hoods operate at a in a laboratory, sometimes whether it was needed or lower face velocity and save energy by reducing the not. Many laboratory research buildings have several amount of conditioned air that passes through them. chemical hoods that remain unused, even as thousands They tend to be more expensive than traditional chemi- of cubic feet of conditioned air passes through them ev- cal hoods, but the energy savings generally result in ery minute. In a typical laboratory building containing a quick payback. They are deeper than a traditional office space, meeting space, and laboratories, the labs chemical hood and may not occupy the same space constitute one-sixth of the floor space, yet consume a in a retrofit situation. See section 9.C.18.104.22.168 for more third of the energy. information. One suburban university that is relatively typical of a research campus conducted a study of the origin of its carbon inventory and determined that 37% was from laboratory buildings, which constitute 15% of the total building area on campus (see Figure 9.15). VIGNETTE 9.2 Typically, at any one time, fewer than half the hoods Sustainability considerations in in a given laboratory are in active use. Chemical hoods laboratory ventilation design are excellent, but they are not the only solution for reducing exposure to a safe level. Where laboratory In the initial design discussions for an aca- chemical hoods are needed, the amount of energy they demic research laboratory, the principal inves- consume can be reduced. (See Vignette 9.2.) tigator called for six 8-ft chemical hoods plus Several options for energy conservation have been two ventilated Class II biosafety cabinets. After presented in previous sections of this chapter. More discussions about how this equipment was to be technologies are being developed and become available used and the operations of the laboratory, the every year. Each deserves attention and scrutiny before EHS staff and the engineers suggested alterna- using them in a research laboratory environment. tives, including ventilated equipment enclosures This section focuses on sustainability with respect and snorkels. These changes resulted in signifi- to ventilation, but sustainability can be supported in cant savings in first costs, space, operating costs, other areas through water conservation, following and energy consumption, while better fitting the appropriate waste disposal techniques, considering needs of the researchers. the principles of green chemistry when performing
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252 PRUDENT PRACTICES IN THE LABORATORY 9.H.2 Automatic Sash Closers for just a portion of that maximum airflow, rather than for a system that handles 100% of the hoods it serves. For most laboratory chemical hoods, especially those The rationale is that it is extremely unlikely that all the on VAV systems, when the sash is closed, they draw chemical hoods would be operating with the sash open much less air, resulting in significant energy savings. at the same time. The diversity factor is the maximum Laboratory personnel do forget to close the sash or find percentage of airflow ever needed at once. it cumbersome to keep closing the sash every time they By designing the system to handle a smaller num- step away. ber of chemical hoods, the system takes advantage of Modern automatic sash closers have a sensor tech- smaller ductwork and fewer fans, resulting in both nology that uses a proximity or motion detector to first-cost savings and ongoing energy cost savings. Pru- sense when there is no one in front of the chemical dent practice adds at least one extra fan to the system hood. The sensor has a timer that can be adjusted to a both for maintenance reasons (always able to have one set time period; after that time, if no one appears to be fan down) and for future growth. working at the hood, the system gently closes the sash. Like a garage door closer, there is usually a sensor at the bottom edge of the sash, such that if anything, even 9.H.5 Lower General Ventilation Rates a pipette, crosses the plane of the sash, the sash will As discussed in section 9.C.4, many laboratories stop closing to avoid breaking or bumping whatever have a minimum of 6 to 12 air changes per hour. is below the sash. Some laboratories have been able to lower these rates Some sash designs include counterweights that based on the materials and operations in the labora- automatically lower the sash to a set level when the tory. Consultants experienced in computational fluid laboratory personnel step away. The sash does not close dynamics modeling are able to take information about completely but does lower substantially. the chemicals and processes and the ventilation system Automatic sash closers can result in significant cost and predict how a lower air change rate might affect savings and add to the safety of laboratory person- laboratory air quality. nel by keeping a barrier between the materials in the Some laboratories have installed active chemical chemical hood and personnel and materials in the monitoring systems that sample for and provide real- laboratory. time measurements of carbon dioxide and specific chemicals, adjusting the airflow in the room as needed 9.H.3 Variable Air Volume Systems with to maintain an acceptable air quality. Limitations do Setback Controls exist for this method, but it may be useful in some situations. Most chemical hoods are used only a portion of the day. An advantage of a VAV system is that individual chemical hoods or an entire system can be adjusted to 9.H.6 Laboratory Chemical Hood a setback mode, a low flow that maintains negative Alternatives pressure but conserves energy. The laboratory chemical hood is a fabulous engineer- The setback mode may be activated in a number of ing control, but it is not the only one. Perform a risk ways, such as: assessment and consider the other alternatives. Many of the alternatives will result in lower energy usage • a timer for an individual chemical hood or an en- without compromising safety. tire system where work schedules are predictable; • occupancy sensors, set back when sensors indi- cate that the laboratory or the chemical hood is 9.H.7 Retro-Commissioning not in use; For facilities with ventilation systems that were • sash position, set back when the sash is fully not designed for energy efficiency, consider whether closed, especially useful in conjunction with au- it makes sense to replace all or parts of the sys- tomatic sash closers; and tem with newer, more efficient alternatives. Retro- • light switch, set back when lights are turned off, commissioning a laboratory ventilation system can indicating that the laboratory is unoccupied. result in large energy savings and a safer ventilation system and may have a relatively short payback pe- 9.H.4 Variable Air Volume Systems, riod. See section 9.B.9 for additional information. Diversity Factors Another advantage of a VAV system with mani- folded exhaust is that the system could be designed
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253 LABORATORY FACILITIES 9.H.8 Components of Heating, 9.I LABORATORY DECOMMISSIONING Ventilation, and Air-Conditioning A laboratory must be properly decommissioned (HVAC) prior to changing its use. Among other steps, decom- There are many technologies aimed at energy con- missioning entails decontamination and the removal servation for ventilation systems. Examples include of hazards to ensure the safety of future occupants chilled beams for cooling labs and offices, reheat sys- and others who may enter the space. Decommission- tems that cool or heat within zones rather than for all ing must be done prior to renovation, even if the space labs on the system, and enthalpy wheels for retaining is to be reused as a laboratory. Because laboratory latent and sensible heat, just to name a few. operations differ, it is appropriate to decommission a Technologies continue to improve and new ideas laboratory whenever there is a significant change in are being tested constantly. The following resources, occupancy. Areas outside of the laboratory, such as mostly available online, may be useful in identifying ventilation ductwork, coldrooms, hallway freezers and and evaluating these systems: common storage areas, should also be decommissioned if they are concurrently subject to a significant change • EPA Laboratories in the 21st Century (Labs 21) in use or occupancy. Decommissioning must also be (http://www.labs21century.gov/), done prior to the demolition of a laboratory. • US Green Building Council’s LEED (http://www. Before decommissioning begins it is important to usgbc.org), and establish a level of cleanliness that meets the regula- • A SHRAE Laboratory Design Guide (http:// tory and institutional safety standards for the next ateam.lbl.gov/). occupancy. Detailed radiological assessment and decontamination guidelines are available in the Multi- Agency Radiation Survey and Site Investigation Man- 9.H.9 How to Choose a Ventilation System ual (MARSSIM), available from the Nuclear Regulatory There is no one choice that is right for every labo- Commission and other government agencies (EPA/ ratory. The designers, the laboratory users, and the USNRC/DOE/DOD, 2000). Although a helpful Labo- facilities staff must discuss the possibilities. EHS ratory Decommissioning Standard is available from the professionals and laboratory managers are helpful in American National Standards Institute (ANSI Z9.11, these discussions as well. The individuals who decide 2008), there are few standards for an acceptable level which systems to install must understand the needs of residual chemical contamination. Even when envi- of the users, and the users must understand how the ronmental cleanup standards exist, it may be difficult systems work, the capabilities and limitations of the to apply them to laboratory decommissioning. systems, and what to expect from them. The facilities Be sure to document the assessment, decontamina- staff must understand how the systems need to be tion and removal activities, and to issue a final clear- maintained, and those who are choosing the system ance statement. A Laboratory Closeout Checklist is need to know whether there is in-house expertise to included on the disc that accompanies this book. It maintain them. may be appropriate to prepare a written Decommis- Check local, state, and federal codes and regulations sioning Plan. before choosing a new system. Only a few actual regu- lations cover ventilation systems, but more and more 9.I.1 Assessment municipalities are adopting international building and mechanical codes. These codes impose limitations on The first step in laboratory decommissioning is to as- manifolding ductwork and may require detection or sess any hazards that may remain in the space. Review sprinklers within ducts. the known or likely historic uses of the space, as well When considering a new technology, benchmarking as records of spills and accidents, laboratory manu- is usually helpful. Find someone who is using a similar als and notebooks, and published papers of research system and discuss their experience. Ask for samples. conducted in the lab. Ask former occupants what haz- Visit laboratories that use similar products. Find the ardous materials they used and if they know of any systems that work best for your applications. Continue contaminated areas. communications between the users and the installers The assessment of radiological hazards is relatively and the maintenance staff to ensure that the systems straightforward and requires standard methods for are working as intended. handheld survey meters and wipe tests for removable Remember that even if all the chemical hoods are contamination. Because it is easy to do, a radiological removed, ventilation is still needed in the laboratory. survey should be done unless it can be assured that no radioactive material had been used in the space.
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254 PRUDENT PRACTICES IN THE LABORATORY Because many chemicals require a unique protocol Substances and Disease Registry’s Minimal Risk Level (MRL) of 200 ng/m3 for non-occupationally exposed for sampling and analysis, a chemical contamination assessment usually requires that the potential contami- individuals. Chapter 6, section 6.C.10.8, includes in- nants be well-defined. A field sampling plan should de- formation on dealing with mercury contamination. scribe how wipe tests will be taken, the wetting solvent Additional mercury testing may be necessary as furni- used, the protocol for grid sampling (or other sampling ture, floors, walls, and plumbing are removed during scheme), necessary analytical sensitivity, and the meth- renovation. odology that will be used to evaluate the results. After hazardous materials and movable equipment have been removed, areas known to be contaminated (e.g., stained floors and cupboards) should be cleaned 9.I.2 Removal, Cleaning, and appropriately, or destructively removed and disposed Decontamination of. Chemical decontamination can be done using The second step in decommissioning is to remove all appropriate surfactant soaps, solvents, neutralizing hazards from the space. Be sure that all chemicals, ra- agents, or other cleaners. dioactive materials, and biologicals have been removed Unless is it known that no biological materials were from use and storage areas, including refrigerators and used in the space, the furniture, equipment, and other freezers. Movable equipment should be appropriately surfaces should be cleaned with an appropriate dis- cleaned and/or disinfected, and removed from the lab. infectant. Sophisticated biological decontamination Residual perchloric acid and mercury contamination technologies are available for areas where high-risk are common concerns for laboratory decommissioning. pathogens have been used. If perchloric acid was used outside of a hood designed As a precautionary measure, it is a standard practice for that purpose, hoods and ductwork can become to remove dusts and other settled particulates via a contaminated with explosive metal perchlorates. (See thorough final wet-cleaning of floors, vertical surfaces section 9.C.2.10.5 for information about the hazards of and furniture using commercial cleaning products. perchloric acid in laboratory hoods and ventilation.) Mercury is used in most laboratories, and mercury 9.I.3 Clearance spills are common. Unless it is certain that no mercury was used, laboratory decommissioning should include Final tests or survey results can be used to verify testing of floors, sinks, cupboards, and molding around decontamination. In some cases regulatory authorities furniture and walls. Be sure to check and clean sink p- allow permanent marking of a porous floor or wall traps. Visual inspection alone is inadequate as historic where a radioactive material or chemical has pen- spills may reach beneath floor tiles and furniture, and etrated deeply, and destructive removal is impractical behind walls. As described in the ANSI Laboratory prior to the building’s demolition. When removal, Decommissioning Standard, modern mercury testing decontamination, and cleaning meet planned decom- utilizes a portable atomic absorption spectrophotom- missioning standards, a final area clearance statement eter with a sensitivity of 2 ng/m3. Decommissioning can be issued, and renovation, demolition, or the new clearance levels consider the U.S. Agency for Toxic occupancy can commence.