DATE: 9-17-03
Safe Use of Compressed Gases In The Lab


A compressed gas is defined as a material in a container with an absolute pressure greater than 276 kilopascals (kPa), or 40 psi (pounds per square inch) at 21oC or an absolute pressure greater than 717 kPa (104 psi) at 54oC, or both, or any liquid flammable material having a Reid vapor pressure greater than 276 kPa (40 psi) at 38oC.
To use compressed gases safely, it is essential that cylinders are stored, handled and are fitted with the correct regulators, piping systems or flow controls and that the properties of gases are fully understood.


1. Storage areas should be:
∑ Away from sources of heat and ignition.
∑ Designated as a no smoking area.
∑ Clearly marked with appropriate warning signs (i.e. flammable, oxidizer, etc.)
∑ Secure and restricted to access by authorized personnel.

2. Cylinders should be stored:
∑ In the upright position.
∑ Properly secured at all times whether empty or full.
∑ Fitted with protective valve cap or guard as supplied.
∑ Segregated according to their hazard category with 20 feet separating incompatible gases.

3. Persons handling cylinders should:
∑ Be familiar with the hazards of compressed gases.
∑ Use a cylinder handcart or other secure transport device to move cylinders.
∑ Use caution to avoid finger pinch points between cylinders.
∑ Always install caps or valve guards when moving cylinders.

4. Compressed gas usage areas should be:
∑ Well ventilated to permit capture, purging or dissipation of gas.
∑ Arranged and maintained to minimize ignition and reaction sources.

5. Compressed gas piping, regulators and flow control equipment:
∑ Must be compatible with the chemical and physical properties of gas.
∑ Must be capable of withstanding gas supply pressures.
∑ Must be installed and operated by trained and qualified persons familiar with the specific hazards of the gases.
∑ Oxygen or oxidant gas handling regulators, piping and equipment must be free of oil, grease and other non-compatible chemicals.
∑ Installations handling flammable gases must be grounded to prevent static build-up.
∑ Installations handling flammable and hygroscopic corrosive gases such as anhydrous hydrogen chloride must be provided with a means for safely purging the system.
∑ Must be leak tested upon installation around valve gland, regulator connections and fittings.

6. Empty compressed gas cylinders must be inspected to assure:
∑ The cylinder valve is closed and not leaking
∑ The supplied cylinder/container valve outlet plug or cap nut is securely refitted
∑ The container valve protection cap is properly fitted

7. Fire emergencies involving compressed gas cylinders require caution:
∑ Don’t take chances to save equipment. When in danger, evacuate the area.
∑ Release pressure in affected pipelines and equipment when safe to do so.
∑ Turn off gas supply to ignited flammable gas leaks if possible.
∑ Extinguish flames from a flammable gas leak by stopping the flow of gas.
∑ Gas cylinders involved in a fire must be taken out of service and returned to the manufacturer for inspection before reuse.

8. PI and lab personnel must be familiar with hazardous gases in their lab. Emergency response for gas leaks will vary according to the chemical hazards involved. Lab personnel should never attempt to repair defective or damaged cylinders or cylinder valves. Some common leak points and their potential repairs are as follows:
∑ Valve outlet /regulator connection – clean dirt in connections, replace damaged regulator fitting or use a new washer.
∑ Valve closure - apply more leverage to handle; if this fails to stop leak label cylinder and return to supplier.
∑ Valve stem spindle – should not attempt field repair, label and return to supplier.
∑ Cylinder valve to cylinder joint - cannot be repaired in the field, label and return to supplier.
∑ Leaking gas control equipment/pipelines – turn off gas supply, release pressure and purge equipment of hazardous gas before attempting repair.

9. Compressed gas cylinder emergency information/service is available from:
∑ The Environmental Health and Safety Department at Pitt (624-9505)
∑ The gas supplier or manufacturer (see cylinder tag for information)


The University of Pittsburgh’s Chemical Hygiene Plan Committee has reviewed and approved this SOP preparation document as attested by the signatures of the Committee Chairperson and the Chemical Hygiene Officer.
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