Guidelines

Storage and Handling of Gas Cylinders - Guidelines

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1. Purpose and Objectives

Compressed gases stored in portable cylinders are hazardous, and risk to people and property must be minimised by correct storage, handling and usage. The use of portable compressed gas storage is widespread and the relevant Australian Standards for example AS4332, Workplace Health and Safety Queensland as well as industry guides, detail correct procedures to ensure gas cylinder safety. This document presents key information available on gas cylinder safety applicable to the UQ work environment.

2. Definitions, Terms, Acronyms

ADG - Australian Dangerous Goods

3. Guidelines Scope/Coverage

This guideline is for all staff, students and contract workers who deliver and work with compressed gas cylinders at UQ.

4. Guidelines Statement

This guideline details the hazards of gas cylinders, along with the correct storage, handling and usage requirements to ensure people and property are not put at risk. The information given is based on minor storage compressed gas quantities that should apply to most areas of UQ.

4.1 Hazards

Always consult the safety data sheet for the gas to determine the relevant hazards.

4.1.1 Chemical

  • Fire or explosion from the release of flammable gases near ignition sources (e.g. acetylene, hydrogen or liquid petroleum gas);
  • Spontaneous combustion from oxidising gases (e.g. oxygen or nitrous oxide);
  • Exposure of people and plant to toxic or corrosive gases (e.g. anhydrous ammonia); or
  • Asphyxiation from some non-toxic, non-flammable gases by displacement of oxygen (e.g. nitrogen, carbon dioxide and argon).

4.1.2 Physical

All compressed gases are hazardous because of the high pressures inside the cylinders. Gas can be released deliberately by opening the cylinder valve, or accidentally from a failed or leaking valve. Even at a relatively low pressure, gas can flow rapidly from an open or leaking cylinder and may present a physical hazard.

Compressed gas containers need regular maintenance and checks to ensure valve seal integrity. Damage to the valve in regulators resulting in seal failure and leakage of the gas can result in:

  • Low boiling point, cryogenic or liquefied gases may cause frostbite on release;
  • Impact to the pressure vessel or structural failure from over use or other defect, resulting in catastrophic failure with the release of shrapnel;
  • A direct stream of high pressure gas causing damage to the ears or eyes.

Unsecured gas cylinders can fall, with the resulting impact shearing off the valve stem. Most cylinder valves are designed to break at a point with an opening of about 75mm. This design limits the rate of gas release and reduces cylinder velocity. However, they can still cause injury, especially smaller lighter cylinders that may 'rocket' into the air.

Large gas cylinders can also be bulky, heavy and awkward objects to move without proper equipment and training. The risk of muscular skeletal injury is higher for the larger size G and F sized cylinders, but is also significant with smaller cylinders due to their low height and heavy weight, especially when full.

5. Suitable Storage

All compressed gases are classified as dangerous goods and must be stored a suitable area to ensure health and safety. The requirements of the storage area will depend on the types and quantities of gas being stored.

5.1 Signage

Where gases are stored in excess of the placard quantities in specified in schedule 11, column 4 (Placard Quantity) of the Work Health and Safety Regulation 2011, placarding is required to be erected.

Refer to Workplace Health and Safety Queensland Guide: Placarding for Storage of Hazardous Chemicals for further information.

5.2 Storage of gases in cylinders

In most laboratories or settings within the University, minor storage quantity rules will apply. Storage of gases in cylinders in quantities not exceeding those in the table below shall be classified as minor storage.

Class of Gas Examples Maximum aggregate water capacity, L
2.1 (flammable gas) LPG, hydrogen, acetylene 500 (eg 10G size cylinders)
2.2 (non-flammable non-toxic gas) compressed air, nitrogen, argon, carbon dioxide, helium 2000 (eg 40G size cylinders)
2.2 (non-flammable non-toxic gas) with class 5.1 (subsidiary risk oxidising gas) oxygen, nitrous oxide 1000 (eg 100G size cylinders
2.3 (toxic gas) methyl bromide, anhydrous ammonia, chlorine 50 (eg 1G size cylinders)

Where gases of mixed classes are kept in minor storage, the aggregate quantity of all gases shall not exceed 2000L and the quantity of each subclass shall not exceed that in the above table.

For further information relating to electrical installations near flammable gas supplies, contact UQ Property and Facilities.

5.2.1 Segregation of DG gases in cylinders (less than 500L)

Corrosive liquids can damage gas cylinders on contact. Flammable liquids can spread a fire across a workplace floor and allow flames to come into contact with gas cylinders. Other dangerous goods may also be adversely affected by gas cylinders in an emergency.

For this reason, gas cylinders are kept separately from other dangerous goods and combustible liquids by at least 5m or by using appropriate fire rated barriers. Segregation of incompatible goods also allows fire fighters to safely use appropriate fire fighting media for each type of goods present.

Gas cylinders must also be segregated from other incompatible gases by at least 3m or more. The following is recommended:

  • Class 2.3 "Toxic gas" and corrosive gases (those with a subsidiary risk of Class 8 "Corrosive") are stored away from all other gas cylinders.
  • Class 2.1 "Flammable gas" must be segregated during storage from all oxidising gases.
Class 2.1 2.2 2.2 (5.1) 2.3
2.1 C C R I
2.2 C C C I
2.2 (5.1) R C C I
2.3 I I I C

C = Compatible

I = Incompatible and should be segregated by at least 3m

R = Reactive and should be segregated by at least 5m

5.2.2 Medical oxygen cylinders

After 1 August 2010, medical cylinders are only be supplied with pin index valve outlets.

What you need to do:

  • Arrange for a replacement medical oxygen regulator in order to be able to connect to the new valve outlet. It is recommended you contact your regulator supplier or medical gas supplier for assistance with your requirements.
  • Medical oxygen with manifold systems will need to have their manifold connections and/or flexible connections changed. Ensure that the new pin-index cylinders have been ordered and are at your site when the conversion occurs to ensure you have continuity of supply.

5.3 Securing cylinders in an upright position

Cylinders should always be stored in the upright position. Some gases (e.g. LPG and acetylene) contain a gaseous and liquid phase. Some flammable gas cylinders contain a pressure relief valve which must be in contact with the vapour phase if the cylinder is to function properly during an emergency.

  • Ensure that cylinders are prevented from falling or being knocked over by securing cylinders using a racking system or using a non abrasive, coated chain that will not be abrasive to the cylinder markings and paint work.
  • If cylinders have been lying on their side, place the cylinder in the upright position and wait 30 minutes before using.

Note: Some cylinders are designed so that they can be stored on their side, e.g. medical oxygen in an oxy-viva set. Consult the SDS or contact your supplier for additional information.

5.4 Location and features of gas stores

Gas stores should be located outdoors in a secured area, e.g. a tamper-proof cage protected from sunlight. Gas storage areas should also provide adequate space to store used or spare cylinders. Storage indoors is not recommended unless the building has been designed for that purpose with appropriate fire rated walls and ventilation. Where gases are stored indoors, additional safety considerations and control measures need to be given consideration.

5.4.1 Outdoor minor storage

Outdoor minor stores of class 2 gases in cylinders shall be separated from other dangerous goods stores by a minimum distance of 3m. They shall be located not less than 1m from any door, window, air vent or duct.

As far as practical, compressed gas cylinders should be stored outside of buildings and the gas reticulated to points of use. These external stores should be secured against damage and tampering and be clear of combustible materials. Gases should not be reticulated at full cylinder pressure and the system should be provided with regulators at the cylinder. The need for high and low pressure cut-off devices should be considered to protect against disconnection of equipment or failure of the regulator.

5.4.2 Indoor minor storage

The indoor use and storage of gas cylinders should be avoided wherever possible. Where it is impractical to provide an outdoor cylinder store, the keeping of cylinders indoors shall be restricted as follows:

  • The total capacity of gas in cylinders allowed for any particular indoor location shall include cylinders in use, spare cylinders in use, and used cylinders awaiting removal.
  • The total capacity of the gases kept shall not exceed one minor storage quantity per 200m2 of floor area. Where the floor area exceeds 200m2 any arrangements that could result in an undue concentration of cylinders shall be avoided.
  • Indoor minor stores of gases in cylinders shall be separated from other minor stores of gases or other dangerous goods stores by a minimum distance of 5m.
  • Except for class 2.2 gases having no subsidiary risks, there shall be no minor storage in basements.
  • Where cylinders are kept inside a building or a confined area, e.g. a shipping container, that building or area shall be adequately ventilated. Such ventilation shall be achieved by natural air movement or equivalent.

For further information on the design and construction of stores, refer to section 4 of AS4332-2004: The Storage and Handling of Gases in Cylinders and the use of compressed gas cylinders in labs in AS2982 and AS2243 part 10 (Chemical Storage).

5.4.3 Ventilation

  • Store gas cylinders in well ventilated areas to prevent build up of escaped gases. Gas monitors for low oxygen or for measurement of the contaminate gas directly may be required to ensure safety.
  • Where possible gases should be stored outside in a cage.
  • Where gases are stored inside a building, a mechanical ventilation system may be required if the natural ventilation is inadequate. Expert advice should be obtained if you are unsure.
  • The mechanical ventilation system must be designed so as to capture escaped gases, not ignite flammable gases, ensure workers are not placed at risk of asphyxiation, or exposed to gases above the relevant National Exposure Standard (NES). National Standards are those stated in the Adopted National Exposure Standards for Atmospheric Contaminants in the Occupational Environment (PDF, 580 KB) National Exposure Standards.
  • AS 4332 The Storage and Handling of Gases in Cylinders is recommended for guidance.

6. Personal Protective Equipment (PPE)

Eye protection, enclosed shoes and safety glasses should be worn in gas cylinder storage and handling areas. Other PPE as required based on the risk assessment that may include thermal gloves, face shield, apron and hearing protection.

7. Safe Handling

The following are some recommendations for safe handling:

  • Avoid knocking cylinders about. Prevent damage to cylinders from impact from other objects (e.g. crashing into other cylinders). Some cylinders (e.g. acetylene) may react violently after being excessively shaken, heated, or knocked about.
  • Cylinders should never be used as rollers to move other objects.
  • When moving cylinders, avoid rolling them. Ensure that an appropriate mechanical handling device, e.g. cylinder trolley with a restraining chain, is used. Release and move one cylinder from the trolley at a time.

8. References

BOC Industry Guidance Document: Guidlelines for Gas Cylinder Safety

AS4332: 'The Storage and Handling of Gases in Cylinders' sets out requirements and recommendations for the safe storage and handling in cylinders, of gases that are classified as Class 2 substances in the ADG Code (i.e. gases that are compressed, liquefied or dissolved under pressure).

Workplace Health and Safety Queensland resource: Gases in Cylinders

For further information of specific gases, the following Australian Standards should be consulted:

  • AS1894: Non-flammable cryogenic and refrigerated liquids
  • AS2982: Laboratory design and construction
  • AS2927: Liquefied chlorine gas
  • AS1596: Liquefied petroleum gas.

9. Further Information and Online Training

Occupational Hygiene Advisors:

Rob Alcock:        r.alcock@uq.edu.au

Terry Johnsen:  t.johnsen1@uq.edu.au

UQ Compressed Gas online training accessed through Learn.UQ: https://learn.uq.edu.au/

  1. Login and click on "UQ Workplace Inductions and OH&S Training" on the home page
  2. Click on "Learning Modules"
  3. Select the compressed gas training module.
Custodians
Director, Occupational Health and Safety
Mr Jim Carmichael
Custodians
Director, Occupational Health and Safety
Mr Jim Carmichael