8

 Storage of Toxic Gases

 

INTRODUCTION

 This chapter states the parameters for storage of toxic gases at Stanford. Storage of toxic gases is strongly discouraged. Only those gases that are currently being used should be on campus.

8.1 Storage Parameters

 All regulated toxic gases must be stored and used in a ventilated gas cabinet, exhausted enclosure, or a ventilated separate gas storage room as defined by the UFC.
Only gases, which are currently being used, can be stored at Stanford. Current usage of a toxic gas is generally defined as using or planning to use the gas within one year. There should be no storage at Stanford of toxic gases that are not currently being used. Gases that are not being used should be returned to the supplier. Toxic gases that are kept for more than one year can degrade, or the cylinder and connections can degrade in such a way as to become very unstable and dangerous. In general, all toxic gas cylinders should be returned to the vendor within one year from the delivery date.

8.2 Compatibility of Materials

 Incompatible classes of regulated materials must be separated by means of 1-hour fire resistive construction, a gas cabinet, or a fume hood. If a gas is stored by itself in a gas cabinet, the gas is automatically considered separated from incompatible materials. However, if the gas is stored in an exhausted enclosure with other substances, the additional materials must be compatible.
Storage compatibility can be determined using Stanford’s Compatible Storage Group system. Each chemical has been assigned a compatible storage group identifier in the Stanford Chemical Safety Database:

A Compatible Organic Bases, Flammables, and Poisons

B Pyrophoric and Water-Reactive Materials

C Compatible Inorganic Bases, Oxidizers and Poisons

D Compatible Organic Acids, Flammables, and Poisons

E Compatible Oxidizers, Organic Peroxides and Acids

F Inorganic Acids not including Oxidizers

G Not Intrinsically Reactive or Flammable

J Poison Compressed Gases; not Flammable or Reactive

K Explosive or Other Highly Unstable Material

L Non-Reactive Flammables or Combustibles including Solvents

X Segregate from ALL Groups and from Each Other Individually

8.3 Storage Requirements

 Please note that only gases in the same storage group can be stored in the same exhausted enclosure.

 
There are several ways to minimize both the quantity and the hazard of toxic gases in a lab:
1. Use good procurement practices. Keep records of usage so that the empty cylinder or other container can be picked up when the full cylinder is delivered.

2. Always try to use the gas that has the lowest toxicity of the alternatives available. Use a low concentration mixture of the gas whenever possible. (See Chapter 3 Regulated Materials)

3. Minimize the quantity of toxic gases in the lab by ordering no more than one year's supply. Storage of gases for more than one year increases the hazard of the gases because the gas may become unstable and more dangerous. In addition, the cylinder, lecture bottle or connections and valves may become worn and subject to failure.

4. Balance the hazard of storing large quantities of a toxic gas with the hazard of frequent turnovers when determining the quantity to purchase. (See page 4-4 of the Stanford Safety Manual for guidance on sizing cylinders for purchase.)

5. Order toxic gases in quantities that require reordering no more than once every one to two months. Frequent bottle changes increase the likelihood of leakage and exposure during the bottle changing procedure and increase downtime of the experiment. Discourage long-term storage in fume hoods. Do not store toxic gases in lab bench drawers or cabinets.

6. Avoid exposing stored chemicals to heat above room temperature, direct sunlight, or other radiant heat sources.

7. Provide for toxic gas storage space adequate to your lab’s research needs.

8. Be sure all storage containers are clearly labeled with the name(s) and hazardous properties of their contents.

9. If exterior storage is necessary, contact the Stanford Fire Marshal at 723-0609.

 

 

Revised December, 1997

© 1998 Stanford University. All rights reserved.