5.E.6 Storing Gas Cylinders
Check applicable international, regional, or local building and fire codes to determine the maximum amount of gas to be stored in a laboratory. These limits vary by storage conditions and type of chemical.
With toxic and reactive gases, or large quantities of asphyxiating gases, a special gas cabinet may be required. Gas cabinets are designed for leak detection, safe change-outs, ventilation, and emergency release.
The following general precautions should be taken when storing compressed gas cylinders or lecture bottles:
• Always label cylinders with their contents; do not depend on the manufacturer’s color code. They may vary across companies.
• Securely strap or chain gas cylinders to a wall or benchtop. In seismically active areas, use more than one strap or chain.
• When cylinders are no longer in use, shut the valves, relieve the pressure in the gas regulators, remove the regulators, and cap the cylinders.
• Segregate gas cylinder storage from the storage of other chemicals.
• Do not store corrosives near gas cylinders or lecture bottles. Corrosive vapors from mineral acids can deface markings and damage valves.
• Keep incompatible classes of gases stored separately. Keep flammables away from reactives, which include oxidizers and corrosives. (For more information on storage of flammable gases, see Chapter 7, section 7.D.3.3)
• Segregate empty cylinders from full cylinders.
• Keep in mind the physical state—compressed, cryogenic, or liquefied—of the gases.
• Do not abandon cylinders in the dock storage areas.
• Return cylinders to the supplier when you are finished with them.
For commonly used laboratory gases, consider the installation of in-house gas systems. Such systems remove the need for transport and in-laboratory handling of compressed gas cylinders. Chapter 6, section 6.H, provides additional information on working with compressed gases in the laboratory.
5.E.7 Storing Highly Reactive Substances
Check applicable international, regional, or local building and fire codes to determine the maximum amount of highly reactive chemicals that can be stored in a laboratory. These limits vary by storage conditions and type of chemical. Follow these additional guidelines when storing highly reactive substances:
• Consider the storage requirements of each highly reactive chemical prior to bringing it into the laboratory.
• Consult the MSDSs or other literature in making decisions about storage of highly reactive chemicals.
• Bring into the laboratory only the quantities of material needed for immediate purposes (<3- to 6-month supply, depending on the nature and sensitivity of the materials).
• Label, date, and inventory all highly reactive materials as soon as received. Make sure the label states
DANGER! HIGHLY REACTIVE MATERIAL!
• Do not open a container of highly reactive material that is past its expiration date. Call your institution’s hazardous waste coordinator for special instructions.
• Do not open a liquid organic peroxide or peroxide former if crystals or a precipitate are present. Call your institution’s hazardous waste coordinator for special instructions.
• For each highly reactive chemical, determine a review date to reevaluate its need and condition and to dispose of (or recycle) material that degrades over time.
• Segregate the following materials:
ο oxidizing agents from reducing agents and combustibles,
ο powerful reducing agents from readily reducible substrates,
ο pyrophoric compounds from flammables, and
ο perchloric acid from reducing agents.
• Store highly reactive liquids in trays large enough to hold the contents of the bottles.
• Store perchloric acid bottles in glass or ceramic trays.
• Store peroxidizable materials away from heat and light.
• Store materials that react vigorously with water away from possible contact with water.
• Store thermally unstable materials in a refrigerator. Use a refrigerator with these safety features:
ο all spark-producing controls on the outside,
ο a magnetically locked door,
ο an alarm to warn when the temperature is too high, and
ο a backup power supply.
• Store liquid organic peroxides at the lowest possible temperature consistent with the solubility or freezing point. Liquid peroxides are particularly sensitive during phase changes. Follow the manufacturer’s guidelines for storage of these