Safe handling of compressed gases. May 30, 2018. Revised:
Department of Materials Engineering
Safe Handling of Compressed Gases
(Copied and Modified from UBC Department of Chemistry. A training record form is included at the end that supervisors or their designates can use to document training.)
Bé Wassink
Compressed gas handling
Chain or strap individually in upright position. Use a heavy chain or a cylinder clamp and strap.
Keep the protective cap in place while moving the cylinder; never move a cylinder with the regulator attached or the cap off.
Always use a hand truck/cylinder cart for transport. Chain cylinders to hand truck.
Do not empty the cylinder (not less than 50 psi remaining).
Keep cylinder valves closed when not in use.
Fittings must be compatible and withstand cylinder pressures.
Do not place cylinders near exit route and doors.
Store away from heat, sun and sources of moisture.
In the lab keep only those cylinders that are actually in use.
Store the smallest size that is available & practical.
Protect cylinders from any objects that might cut or scrape them.
Do not drop cylinders or otherwise permit them to strike each other.
Store according to compatibility groups.
Use the proper regulator for a particular gas. Never modify a regulator. A CGA number should be stamped somewhere on the regulator. You can search this online for the intended gas service.
Bring defective regulators to stores to be sent out for repair. Do NOT attempt to repair a regulator yourself.
Review MSDS for gas specific information.
NEVER use a compressed gas cylinder without first having been trained by qualified personnel.
Training must include instruction, demonstration of how to use a cylinder, remove and install a regulator, and observation of student/employee doing the same.
Installing a regulator
Specific measures for individual regulators and intended service can be found online through the manufacturer’s websites. Check that the regulator is not obviously damaged. Make sure it has the necessary gauges and that they are all reading zero. Make sure the threads of the regulator fitting are clean and not damaged. Carefully inspection wetted parts for grease or oil. Oxidizing gases (e.g. oxygen) can react explosively with traces of combustible material. If you suspect any contamination clean it off with Simple Green or another suitable degreaser. Make sure that the threads of the gas cylinder do not appear damaged and also are clean. NOTE: connecting piping and fittings are all wetted parts.
Never use Teflon tape (or any other lubricant or sealant) on the tank threads. These are parallel threads and Teflon tape will not help present leaks; it might make it worse. Teflon tape may be used to assist sealing of pipe threads. These are tapered threads that tighten as they enter the outer threaded hosuing.
Hold the regulator with one hand and carefully thread the fitting onto the tank. Oxidizing gases and inert gases have normal “right hand” threads (tighten by turning clockwise); reducing gases (fuels) have “left hand” threads (tighten by turning counterclockwise). Hand tighten. It may be helpful to gently wriggle the regulator as you tighten the fitting. Use a 1 1/8 inch wrench to tighten the regulator onto the tank. The regulator will tend to turn in the direction of movement of the wrench. To prevent the gauges from jamming into the tank valve turn the regulator as far away as possible, opposite the direction of rotation of the wrench. Tighten the regulator until it feels firmly secured. Do NOT overtighten. If you do the threads can be damaged. Severe overtightening can strip the threads and cause the regulator to fly off the tank when the valve is opened. This could cause severe injury.
Once
the regulator is tight, ensure that the outlet valve is closed and
the pressure adjusting valve is fully threaded out (no pressure
delivered to the outlet). Stand so that you are not facing the tank
outlet. If the regulator were to come off upon opening the tank valve
you need to be off the line of travel. Carefully open the tank valve.
Listen for hissing that might indicate a leak. If you hear hissing
close the tank valve. You can try tightening the regulator more, but,
as indicated above, do NOT overtighten it. If the hissing
persists
then do not use the tank. Obtain assistance from the lab manager of
senior lab personnel who are experienced in the use of compressed
gases. If the tank threads are damaged and causing the leak the tank
must be returned to stores. Discuss the problem with the stores
keeper, who will be able to contact our compressed gas supplier.
If there is no hissing, open and close the tank valve a couple times. Now leave it closed. Observe the needle on the inlet pressure gauge. If it drops slowly there is a leak between the tank and the regulator. Tightening the regulator can be attempted, with caution as noted above. There might also be a loose connection between the threads of the inlet fitting and the regulator. “Snoop” solution applied to the connections can be used to check for leaks. Call in the lab manager or other qualified personnel to assist with regulator issues.
If the inlet pressure gauge pressure remains constant, then open the tank valve and thread in the pressure adjusting knob to apply a suitable pressure to the outlet (outlet valve still closed). Close the tank valve. Again check for loss of pressure on the inlet pressure gauge. If this occurs the outlet valve may be leaking, or, there is another leak elsewhere. Don’t use the regulator and ask for assistance as above. If the inlet pressure gauge reading stays constant then the regulator should be working properly.
To remove a regulator make sure the tank main valve is closed. Bleed excess pressure from the system by opening a suitable valve. If the gas is toxic pressure relief should vent to a fume hood. Thread out the pressure adjusting knob. Ensure the outlet valve is closed. Use a 1 1/8 inch wrench to loosen the regulator fitting from the tank. Hold the regulator in one hand and fully loosen the regulator fitting to remove the regulator. Handle the regulator gently. It can be damaged by rough handling.
Store regulators in a sealed plastic bag. Make sure it has a tag that describes its intended gas service. Defective regulators can be brought to stores to be sent out for repair.
Compressed gas cylinder and regulator training record
Indicate with your initials that you have completed the following and sign at the bottom.
I have:
(1) Viewed the compressed gas safety portion of the MTRL Departmental Safety Seminar (mtrl.ubc.ca). ________
(2) Reviewed “Safe Handling of Compressed Gases” ________
(3) Been:
instructed on how to use a compressed gas cylinder and on how to change a regulator. _______
shown how to use a compressed gas cylinder and how to change a regulator. _________
observed using a compressed gas cylinder and changing a regulator. _________
by (name and signature): __________________________________
Your name and signature _________________________________________
Date: _________________ (including year)
1 FIG 131 DIVIDEBYZERONOEXCEPTIONHANDLINGJAVA 2 AN APPLICATION
13 SPØRSMÅL FRA MARGUNN EBBESEN HØYRE FORSKJELLSBEHANDLING AV ELEVER
16 Manual Handling 1611 Contents aim 1621 Introduction
Tags: compressed gases., a compressed, handling, compressed, revised, gases