should be moved to an isolated area, away from combustible material if the gas is flammable or an oxidizing agent, and signs should be posted that describe the hazards and state warnings. Care should be taken when moving leaking cylinders of flammable gases so that accidental ignition does not occur. If feasible, leaking cylinders should always be moved into laboratory hoods until exhausted.

  • Corrosive gases. Corrosive gases may increase the size of the leak as they are released, and some corrosives are also oxidants, flammable, and/or toxic. The cylinder should be moved to an isolated, well-ventilated area, and suitable means used to direct the gas into an appropriate chemical neutralizer. If there is apt to be a reaction with the neutralizer that could lead to a "suck-back" into the valve (e.g., aqueous acid into an ammonia tank), a trap should be placed in the line before starting neutralization. Signs should be posted that describe the hazards and state warnings.

  • Toxic gases. The same procedure should be followed for toxic gases as for corrosive gases, but for the protection of personnel, a special warning should be given for the added hazard of exposure. The cylinder should be moved to an isolated, well-ventilated area, and suitable means used to direct the gas into an appropriate chemical neutralizer. Signs should be posted that describe the hazards and state warnings. Appropriate personal protective equipment should be worn. (See also section 5.D.6.)

5.C.11.8 Handling Spills of Elemental Mercury

Mercury spills can be avoided by using supplies and equipment that do not contain mercury. However, most mercury spills do not pose a high risk. The initial response to a spill of elemental mercury should be to isolate the spill area and begin the cleanup procedure. Those doing the cleanup should wear protective gloves. The cleanup should begin with collecting the droplets. The large droplets can be consolidated by using a scraper or a piece of cardboard, and the pool of mercury removed with a pump or other appropriate equipment. A standard vacuum cleaner should never be used to pick up mercury. If a house vacuum system is used, it can be protected from the mercury by a charcoal filter in a trap. For cleaning up small mercury droplets, a special vacuum pump may be used, or the mercury may be picked up on wet toweling, which consolidates the small droplets to larger pieces, or picked up with a piece of adhesive tape. Commercial mercury spill cleanup sponges and spill control kits are available. The common practice of using sulfur should be discontinued because the practice is ineffective and the resulting waste creates a disposal problem. The mercury should be placed in a thick-wall high-density polyethylene bottle and transferred to a central depository for reclamation. After a mercury spill the exposed work surfaces and floors should be decontaminated by using an appropriate decontamination kit.

5.C.11.9 Responding to Fires

Fires are one of the most common types of laboratory accidents. Accordingly, all personnel should be familiar with general guidelines (as stated below) to prevent and minimize injury and damage from fires. Handson experience with common types of extinguishers and proper choice of extinguisher should be part of basic laboratory training.

(See also Chapter 6, section 6.F.2.)

The following should be noted:

  • Preparation is essential! Make sure all laboratory personnel know the locations of all fire extinguishers in the laboratory, what types of fires they can be used for, and how to operate them correctly. Also ensure that they know the location of the nearest fire alarm pull station, safety showers, and emergency blankets.

  • Even though a small fire that has just started can sometimes be extinguished with a laboratory fire extinguisher, attempt to extinguish such fires only if you are confident that you can do it successfully and quickly, and from a position in which you are always between the fire and an exit to avoid being trapped. Do not underestimate the danger from a fire, and remember that toxic gases and smoke may present additional hazards. Notify trained professionals.

  • Fires in small vessels can usually be put out by covering the vessel loosely. Never pick up a flask or container of burning material.

  • Extinguish small fires involving reactive metals and organometallic compounds (e.g., magnesium, sodium, potassium, and metal hydrides) with Met-L-X® or Met-L-Kyl® extinguishers or by covering with dry sand. Because these fires are very difficult to extinguish, sound the fire alarms before you attempt to extinguish the fire.

  • In the event of a more serious fire, evacuate the laboratory and activate the nearest fire alarm. Upon their arrival, tell the fire department and emergency response team what hazardous substances are in the laboratory.

  • If a person's clothing catches fire, have him or her immediately drop to the floor and roll. Dousing with water from the safety shower can be effective. Use fire blankets only as a last resort because they tend to hold in heat and to increase the severity of burns. Remove contaminated clothing quickly, douse the person with water, and place clean, wet, cold cloth on burned areas. Wrap the injured person in a blanket to avoid shock, and get medical attention promptly.



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