Gas Safety Control in the Laboratory

- Apr 30, 2020-

A number of gases are used in laboratories to support various applications such as Chromatography (GC and LC-MS) Spectroscopy, ELSD and Sample Preparation, to name just a few. Helium, hydrogen and nitrogen are some of the most common gases used by labs for these applications.

Gas is typically supplied to laboratories in one of 3 ways:

• Dewar
• Cylinders
• Gas generator

Traditionally cylinders have been the most common method of gas supply and they are still widely used in labs around the world. If you use cylinders in your lab you should follow the safety tips below.

1. Cylinders should be stored in a cool, dry place away from heat. Flammable cylinders should be stored separately from oxygen or hydrogen cylinders.

2. Be careful when moving the cylinder and removing the cylinder cap. The gas inside is highly pressurized.

3. Cylinders in use should be checked once every three years. The cylinders with corrosive gases should be inspected every two years and unqualified cylinders should not be used.

4. Hydrogen cylinders should be placed in a dedicated place away from the laboratory, connected with copper/stainless steel piping into the laboratory and secured to prevent tampering. Pipework should be regularly leak-checked to prevent large leaks of hydrogen.

5. It is best practice not to use the entire contents of the gas cylinder. Normally the last 10% is not used, since this can contain moisture, hydrocarbons and other impurities that can cause contamination of instruments. Pressure within the cylinder prevents air entering the cylinder so it is advisable to ensure the residual pressure never drops below 0.5MP (70 psi).

6. When using cylinder gas, a 2-stage regulator with a pressure relief valve should be used. Flammable gases will require a regulator with left-hand thread. It is important to slowly open and close the pressure regulator and valve. First the cylinder pressure should be checked and then supply to the application should be carefully regulated until the recommended pressure of gas is supplied.

7. When using a high-pressure cylinder, the operator should not stand in a position in front of the cylinder connection to avoid potential injury. Once connected, you should regularly check for leaks and pay attention to pressure gauge readings.

8. Hydrogen cylinders should be equipped with special regulators, and contact with oil is strictly prohibited. The operator should not wear certain items of clothing around these cylinders such as materials which can become static and cause a spark, as hydrogen is extremely flammable. For all flammable gas and combustion gas cylinders, the storage distance from an open flame should be greater than ten meters. If this is not possible, use isolation and other safety measures.

Following these tips should ensure your use of gas cylinders is as safe as can be. However, gas cylinders are inherently dangerous and introduce many risks into the laboratory environment. These risks should be carefully considered when choosing or reviewing a laboratory’s gas supply.