Stanford University

Compressed Gas Leak Test Procedure

How to use this tool

How to use this tool

At Stanford University, all toxic gas cylinders will be tested for leaks prior to removing cylinders from the delivery vehicle, if possible. Also, non-toxic gas cylinders such as flammables should be tested for leaks before acceptance. Leaking gas cylinders will not be accepted. The Principal Investigator (PI) who ordered the gas cylinder is responsible for ensuring that the cylinder is leak tested. Similarly, all compressed gas experimental apparatus should be leak tested periodically per the applicable experimental protocol. Only individuals trained in the use of leak detection methods should perform this leak test procedure.

Leak Detection Methods

The preferred and primary method for leak detection is a direct reading instrument with a sensor that uses thermal conductivity different from that of the ambient air for detection, such as the Matheson LeakHunter Plus Model 8066 or its equivalent. This type of detector is highly sensitive and can locate leaks too small to bubble quickly with a liquid solution leak detector.

Gases and vapors with thermal conductivity different from air can be detected with this method, and some are listed in the table below.

An alternate method, if the primary method cannot be used, is liquid solution leak detection such as the Matheson Detect-A-Leak™ or equivalent that meets or exceeds MIL-L-25567D Type I and II specifications.

 
Gas Detection limit ACGIH TLV TWA (ppm)
Gas Detection limit ACGIH TLV TWA (ppm)
Acetone 10 cc/min 500
Ammonia 5 ppm 25
Arsine 0.3 ppm 0.05
Benzene 10 cc/min 0.5
Carbon Monoxide 1 ppm 25
Chlorine 7 ppm 0.5
Diborane 0.15 ppm 0.1
11-Dichloroethane 10 cc/min 100
Ethanol 10 c/min 1000
Ethylene 1 cc/min N/A
Ethylene Oxide 350 ppm 1
Formaldehyde 10 cc/min C 0.3
Freon 12 1 cc/min 1000
n-Hexane 10 cc/min 50
Hydrogen 10 ppm N/A
Hydrogen Bromide 1 ppm C 3
Hydrogen Chloride 1 ppm C 5
Hydrogen Selenide 0.5 ppm 0.05
Hydrogen Sulfide 1 ppm 10
Isopropyl Alcohol 10 cc/min 400
Methane 1 cc/min N/A
Methyl Bromide 40 ppm 1
Methyl Chloride 50 ppm 50
Methyl Ethyl Ketone (MEK) 10 cc/min 200
Phosphine 0.13 ppm 0.3
Propane 1 cc/min 2500
Silane 0.3 ppm 5
Sulfur Dioxide 1 ppm 2
Toluene 10 cc/min 50
Trichloroethylene 10 cc/min 50
Vinyl Chloride 10 ppm 5
Xylene 10 cc/min 100
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