Compressed Gas Safety

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Compressed Gas Safety

Gas is supplied to the LGSW Chemistry laboratory by pressurised gas lines. It may, however, be necessary to occasionally use cylinders of compressed gas. These rules apply mainly to the use of cylinders but also apply to pressurised gas lines.

Gas cylinders:	Are top-heavy and could cause serious crush injuries on falling.
	Contain contents at high pressure that constitutes considerable stored energy, sudden release of which can be highly dangerous. For example, a cylinder of compressed breathing air used by SCUBA divers has the explosive force of 1 1/2 pounds of TNT: A cylinder fractured at the neck becomes a missile that can go through a wall.
	May contain toxic, flammable or fire-promoting materials; escape of this may lead to fire, explosion or deadly concentration of gas.

In order to ensure gas cylinder safety:	All cylinder valve spindles have right-hand threads. NON-COMBUSTIBLE gas cylinders (e.g.: carbon dioxide, air, nitrogen etc;) have right-hand threaded heads. COMBUSTIBLE gas cylinders (e.g.: acetylene) have left-hand threaded heads.

	The following rules are mandatory:
Training:	Only individuals properly instructed by the Chemist are allowed to use gas cylinders.
Cylinder selection:	Never use a cylinder that cannot be positively identified. Do not rely on colour coding; cylinder colours may vary from supplier to supplier. Do not remove safety caps from new cylinders until you are ready to use it; these caps protect the valves.
Setting up for use:	Before use, inspect connections, regulators, pressure release facility, valves and hose lines. Rubber tubing should not be used. Keep cylinders away from sources of heat and corrosion and ensure that they are located against an outside wall or secured to the bench with the correct cylinder bracket and always stored in an upright position. Place each cylinder so that the main valve is always accessible. Always use the appropriate regulator on a cylinder. If a regulator will not fit a cylinder's valve, replace the cylinder, not the regulator. Do not attempt to adapt or modify a regulator to fit a cylinder it was not designed for. Regulators are designed to fit only specific cylinder valves to avoid improper use. If a cylinder is leaking, report it to the Chemist who will have it removed.Cylinder valves or regulator fittings must never be lubricated or greased; this can lead to fire or explosion. When equipment is connected to a cylinder, always test for leaks by applying a dilute solution of washing-up liquid and watching for bubbles. Open cylinder valves slowly. Excessive force must not be applied to valve spindles or regulator securing nuts; only standard valve keys and regulator spanners may be used. If pressurised gas is introduced into glass apparatus, the equipment must be shielded. Close the main cylinder valve when you have finished.

Moving cylinders:	When being transported, ensure that the cylinder valve is closed and that the regulator has been removed. Cylinders must not be rolled nor used as rollers, supports or jacks etc; When handling gas cylinders, ensure that it is not dropped and that it does not hit anything.against anything.
	Cylinders containing permanent (i.e.: non-liquefied) gases must be operated with the correct type of regulator fitted. The cylinder valve must not be used to regulate the gas flow. Cylinders of liquefied gases may, depending on the supplier's instructions, be used with or without a regulator.

	All cylinders must be turned off at the cylinder valve when not in use.

Care of empty cylinders:	Never completely empty a cylinder. To prevent contamination of any residual gas, leave approximately 25psi. The valve on a discharged gas cylinder must be closed. Always clearly mark empty cylinders and store them separately. Never attempt to transfer gas from one cylinder to another. The contents may be incompatible with each other or with the cylinder material.

Specific instructions for acetylene cylinders:	Cylinders of acetylene must be operated in conformity to the '21 POINT CODE' documented in the HSE publication 'Use of Acetylene'.
	Acetylene cylinders must be fitted with a flash-back arrester.
	Acetylene must not be used with piping or joint fittings that contain copper (or silver).