Gases and gas cylinders

Gas may present hazards depending on its inherent properties and how it is used. Gas can be handled safely if appropriate safety and protective measures are followed before work begins.

Like chemicals, gases are classified and labelled in accordance with European legislation.

All gases must be registered in the chemical inventory, together with their Safety Data Sheets (SDSs).

Anyone handling gases and gas cylinders must receive local, laboratory-specific training in the use of gases and the associated health, safety and environmental requirements. In addition, anyone handling gases must complete the online Gas Safety course.

At MN, we use both gas cylinders and central gas supply systems.

• Flammable gases must be stored in cabinets ventilated to the open air.
• All gas cylinders must be secured, for example by a chain fixed to the wall.
• All use of gases must be risk assessed. See the "Risk Assessment Guide". Use the gas safety data sheet as the basis for the risk assessment. A documented risk assessment must be available for all use of gases.
• Use appropriate personal protective equipment (PPE).
• Consider using gas detection equipment.

Gas Equipment

• Valves: Regulators and non-return valves connected to gas cylinders must be suitable for the gases concerned. They should be inspected and maintained regularly. Regulators should be serviced or replaced every five years.
• Hoses: A replacement schedule for gas hoses should be established, for example every three to five years.
• Cryogenic gas containers: All containers used for cryogenic gases must be suitable for storing such gases.

Cryogenic Gases

Because cryogenic gases evaporate rapidly, they must be stored in well-ventilated areas.

When handling cryogenic gases, use PPE such as a face shield, sturdy loose-fitting gloves and closed, robust footwear.

Transporting containers of cryogenic gas in lifts presents an asphyxiation risk due to gas evaporation. Two people must be present: send the container in the lift on its own, preferably with an “I am travelling alone” sign attached to it.

Pressurised cryogenic containers must be inspected every five years.

Remember that liquid nitrogen expands when it becomes a gas: 1 litre of liquid nitrogen produces 700 litres of gas.

Dry Ice

Dry ice is carbon dioxide in solid form. It is colourless and odourless, has a temperature of -78 ^oC, and may therefore cause cold burns on contact with the skin.

Dry ice sublimates directly into carbon dioxide gas, which displaces air and may cause asphyxiation. At room temperature, 50–60% of dry ice will sublimate within 24 hours. In a freezer room at -20 ^oC, 25–30% will sublimate within 24 hours.

In laboratories, dry ice must be stored only in small quantities and in well-ventilated areas, such as a fume cupboard.

Any transport of dry ice by car must take place in a vehicle with a separate load compartment.

Gases and gas cylinders in laboratories present a significant risk to both people and property. Work involving gases requires an assessment of whether gas alarms need to be installed. Strict requirements apply to work involving toxic and flammable gases.

Gas Cylinders and Pressurised Gas

Uncontrolled heating may cause a substantial increase in pressure, which can result in a gas cylinder exploding.

Flammable Gas

When ignited, flammable gases burn in air and are classified as "flammable substances".

• The most commonly used flammable gases and combustible mixtures include hydrogen, methane, propane, carbon monoxide, hydrogen sulphide, 10% methane in argon, Formier gas (10% hydrogen in nitrogen), and acetylene. Acetylene also presents additional specific hazards. This is not an exhaustive list of flammable gases.

Asphyxiation

• When air is diluted with any gas other than oxygen, its oxygen content is reduced.
• There is always a risk of air dilution and oxygen deficiency where gases are used and the air in the room is not changed frequently enough, or where the room volume is too small. If this presents a risk, alarms must be installed in the room.
• Gases which may present an asphyxiation hazard include nitrogen, argon, helium, carbon dioxide, nitrous oxide, ammonia, hydrogen, methane and propane.

Oxygen Enrichment

Oxygen is a colourless, odourless and tasteless gas that presents a particular fire hazard.

• It is not itself flammable or explosive, but all combustion occurs more rapidly in oxygen than in air.
• At high oxygen concentrations, combustible materials ignite more easily, and materials normally considered non-combustible may catch fire.

Cold Burns

Liquid cryogenic gases have extremely low temperatures.

• Contact with the skin, or with objects cooled by these gases, may cause severe cold burns.
• The most common liquid cryogenic gases are nitrogen, helium and oxygen.

Toxic Gases

• All unpleasant-smelling or irritating gases are toxic, but some toxic gases are odourless.
• The need for alarms must be assessed in rooms where toxic gases are used.
• Examples of toxic gases include ammonia, chlorine, carbon monoxide and hydrogen sulphide.

Before Ordering

Before purchasing a new gas that is not already used in your laboratory, you must check the storage and safety conditions. Use of the new gas must be risk assessed before purchase, and the person responsible for the room must be informed of its intended use. The SDS for the new gas must be registered in the chemical inventory.

For ordinary use, rental cylinders supplied by a gas supplier must be used. The gas supplier will take back rental cylinders.

Before purchasing gas cylinders ranging in size from a few millilitres to 10 litres, the user must:

• Clarify disposal arrangements and disposal costs.
• Ensure that disposal costs are covered by the relevant unit.

Ordering Procedures

The following requirements apply when ordering gases:

• Only employees may order gases.
• Gas orders must be approved by the project leader and the person responsible for the room. The person responsible for the chemical inventory must be copied into the order.
• The gas risk assessment must be attached to the order, either as a link or a file.
• The order must state the room number in which the gas is to be stored.
• Wherever possible, gases must be ordered only from contracted suppliers.

Receipt

The SDS for the gas must be registered in the chemical inventory before the gas is used. Ensure that you receive an SDS from the supplier.

Receiving procedures vary between buildings.

• Gas cylinders must be transported using a trolley designed for gas cylinders.
• Gas cylinders must always be transported with the valve-protection cap fitted.
• A trolley and valve-protection cap must also be used when a gas cylinder is only being moved a few metres.

• Gas cylinders may only be stored in laboratories that are in use.
• Gas cylinders must be securely restrained to prevent them from falling over.
• Flammable, toxic and oxidising gases should be stored in fire-resistant, ventilated cabinets.
• LVB: Gas cylinders must be stored in a local gas storage room or in a gas safety cabinet in the laboratory. Gas cylinders outside a gas safety cabinet are not permitted unless authorisation has been granted on the basis of a risk assessment and for a limited period of use.

• Regulations relating to the handling of flammable, reactive and pressurised substances, and equipment and installations used in such handling (Norwegian)(Lovdata)
• Norwegian Directorate for Civil Protection (DSB) guidance on the Regulations relating to the handling of hazardous substances (Norwegian)
• DSB guidance note on the storage of hazardous substances (Norwegian)