Compressed gas cylinders policy

Policy statement

University of Dundee recognises the risks arising from the storage, handling and use of compressed gas cylinders and is committed to reducing these risks to a level that is as low as is reasonably practicable through a pro-active management program. This program will be based upon training staff in operating procedures that are developed from risk assessments.

Arrangements

Deans/Directors will ensure that risk assessments and safe operating procedures for the storage, handling and use of compressed gas cylinders are carried by competent staff following the Guidance on this page.

Deans/Directors will take reasonable steps ensure that only staff authorised to use compressed gas cylinders can do so after they have been instructed in safe operating procedures.

Staff and post-graduate students must follow safe operating procedures at all times, and report any shortcomings or concerns to their line manger, or School Safety Representative.

Safety Services will provide upon demand general awareness training in the safe use of compressed gas cylinders.

Guidance Note on Use of Compressed Gases

Hazards

Hazards involved in using cylinders of compressed gas are:

1. sudden release of stored energy
2. properties of gas stored under pressure including flammability, explosive, toxicity, oxidising, asphyxiation, corrosiveness or combinations of these properties
3. moving heavy objects

Inventory

Schools must hold an inventory that is updated regularly. A Materials Safety Data Sheet for all the types of gas in storage or in use should be held with the inventory. A copy of the inventory must be kept with fire plans.

Storage

External store

A purpose-built store as detailed by British Compressed Gas Association (BCGA) should be used. Contact Safety Services for further details, but essentially:

• Store must be cool, dry and well ventilated
• Never accept or use leaking cylinders
• Cylinders must be clearly marked with the content of the gases inside. The colour of the cylinders cannot be relied upon for identifying their content
• Cylinders must be stored upright and secured from falling by chains and straps
• Cylinders should be individually secured; using a single restraint strap around a number of cylinders is not effective
• Cylinders must be stored in compatible groups i.e. flammables must be separated from away from oxidizers
• Valves of 'empty' cylinders must be closed to avoid contaminants (e.g. water) from entering cylinder. Remember 'empty' cylinders contain gas at least at atmospheric pressure
• Keep valve protective caps in place when cylinders are not in use
• Empty cylinders must be clearly marked, and separated from full

Within buildings

Whilst it is desirable to have gases piped into buildings from external stores in many cases this is not reasonably practicable. In such cases it is reasonable to store cylinders within buildings so long as the following is observed:

• Least hazardous gas available for the purpose is used
• Minimum number and size possible is used
• They are secured vertically to wall or bench
• They are not stored beside doors or escape routes
• They are stored in adequately ventilated rooms
• They are stored away from sources of heat or ignition
• They are stored within view of operator
• They are not placed where objects may strike or fall on them, possibly damaging the cylinders or their components
• Every cylinder must have means of closing valve (i.e. hand-wheel or suitable spanner)
• Cylinders not in use are returned to the store as soon as possible

Transport

Observe the following points when transporting cylinders:

• Use the correct cylinder trolley for long distance, with cylinders secured with a chain or strap
• 'Churning' may be used for short distance on level floor (with suitable gloves, boots and training provided)
• Valve must be closed, and protective valve cover in place
• Remove regulator and hoses before transport
• Don't use the protective valve caps for moving or lifting cylinders
• Don't drop a cylinder, or permit them to strike each other violently or be handled roughly
• Do not drag, roll, or slide cylinders

Gas delivery system

Cylinder valve safety issues

• Inspect the cylinder valve before use, if it looks damaged in any way then return to supplier
• Any cylinder with a valve that cannot be opened by hand or using suitable tool must be returned to the supplier
• Do not use a pipe wrench, hammer, or extension rod to open or loosen a cylinder valve
• Inspect the valve for dirt or contamination, if you discover oil or other hydrocarbons return to supplier
• If dirty clean valve with clean lint free cloth, or clean dry low pressure air
• 'Snifting' is not advised

Regulator safety issues

• Always use a regulator of the correct type with a suitable pressure output range for the intended application: cylinders must not be used without an appropriate regulator
• Regulators must conform to BS EN ISO 2503:1998
• Never force a regulator that does not fit the cylinder
• Never use adapters for attaching regulators
• Do not force fit regulators or fittings to cylinders
• Treat regulators as delicate instruments, and store them carefully so that they are not jarred or knocked, and inlet and outlet connections are kept clean
• Competent staff should check Regulators for damage on a regular basis
• A Regulator replacement programme should be implemented based upon BCGA CP4 Guidelines

When fitting regulators to cylinders observe the following points:

• Check for damage before use e.g. damaged pressure gauges or indicators, inlet or outlet threads
• Make sure the threads on both the regulator and the cylinder valve are clean and in good condition
• If an 'o' ring is fitted to the inlet check for damage and replace if required
• Before fitting a pressure regulator always screw out the pressure adjusting screw so there is no flow through the regulator when the cylinder valve is opened
• The use of tape (e.g. Teflon) on the threaded connection is not recommended and is unnecessary if the regulator and valve threads are in good condition
• Holding the regulator vertically and horizontally at a right angle to the cylinder head connect it to the cylinder valve by closing the thread finger-tight. The thread should move very easily, if it does not it is either damaged or you are not holding it at right angle, i.e. are damaging it as you try to force it in. Using a wrench tighten the connection with a maximum of one turn. Never use excessive force to tighten the connection
• Leak check your connection using either commercially available ASnoop@ or a mixture of water/isopropanol/dish soap (100:100:1)

Flashback arrestor safety issues

• Fit a flashback arrestor when using cylinders containing flammable (e.g. propane, acetylene, hydrogen) or oxidising gases (e.g. oxygen) to prevent flames travelling back into cylinders
• Use an arrestor with cut off valve to automatically shut off gas flow in hazardous areas such as laboratories

Non return valves/check valve safety issues

• Fit non-return valves that conform to BS EN 730 to prevent backflow at high and low pressures

Hoses

• Use hoses that comply with BS EN 559, and connections that comply with BS EN560
• Always use correct hose for gas with correct pressure rating
• Adopt standard colour coding: blue for oxygen, red for acetylene, and orange for propane
• Inspect for damage before use e.g. cuts, abrasions
• Use proper connectors, check regularly, never use twisted wire to secure hose
• Use hoses that are the correct length, they have to be long enough allow the cylinders to be positioned safely from flying sparks and other sources of heat
• Use proper connectors to couple hoses together if required
• Position hoses away from working area
• Ensure the operator always has easy access to the cylinder valve so that it can be closed in an emergency
• Purge hoses before lighting a torch
• Ensure hoses are of equal length, do not coil surplus hose around cylinder or on floor adjacent to cylinder, unwind and position it behind you
• Use a hose check valve to prevent backfeeding
• Check for leaks at especially at connections when equipment is assembled
• Use a solution of Teepol HB7 in water, or a proprietary leak detecting fluid. Wipe the area dry with lint free cloth

Use

• Notify the supplier if you suspect that a contaminant has entered the cylinder
• Be sure all connections are tight. Use soapy water to locate leaks
• Keep cylinders valves, regulators, couplings, hose and apparatus clean and free of oil and grease
• Safety devices and valves shall not be tampered with, nor repairs attempted
• Regulators shall be removed when moving cylinders, and when cylinders are empty
• The cylinder valve should always be opened slowly. When a special spanner is required to open a cylinder or manifold valve, the spanner shall be left in place on the valve stem when in use; this precaution is taken so the gas supply can be shut off quickly in case of an emergency; and that nothing shall be placed on top of a cylinder that may damage the safety device or interfere with the quick closing of the valve
• Gases must never be mixed inside cylinders
• Close cylinder valves when not in active use
• Check if the proper type of regulator is fixed to the cylinder valve outlet. Check if the pipe lines and hoses are properly connected and securely clamped
• Check cylinders, cylinder valves, couplings, regulators, hoses, and apparatus are free of oily or greasy substances. This is especially important for oxygen cylinders. Not observing this may result in an explosion
• Turn the pressure adjusting screw of the regulator counter-clockwise until it turns freely to ensure that the regulator is off.
• Slowly open the cylinder valve (anti-clockwise) using the correct spindle key or hand-wheel until the cylinder pressure gauge on the regulator reads the cylinder pressure. Do not stand directly in front or behind the regulator when opening the valve since there is a risk of it failing when pressure is applied so stand aside when opening the cylinder valve.
• With the cylinder valve open, set the desire deliver pressure by turning the pressure adjusting screw clockwise until the desired pressure is reached
• Always keep the cylinder valve free of obstructions such as tools, rags, and hoses etc. to permit easy and immediate gas cut off
• Before removing the regulator, make sure that the cylinder valve is closed.

Procedure for opening and shutting down cylinder valves

• Never fully open cylinder valve, always turn it back at least half a turn to avoid seizure in open position
• If you cannot open the cylinder valve with the correct spindle key or hand-wheel, then return cylinder to supplier, do not use excessive force or anything but the recommended key
• When the work is finished, always turn off the cylinder valve first and then the regulator. Close the valve by turning it clockwise, and just enough to stop the gas completely, do not wrench it shut. The pressure gauges should be brought back to zero. Use the cylinder valve instead of the regulator valve for turning off the gas.
• Remember when not in use, always close the cylinder valve

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