College of Engineering Laboratory Procedure
NON-TOXIC, NON-FLAMMABLE COMPRESSED GAS
CYLINDER CHANGE
Dept: Multi-department
Brief Overview &
Scope
Potential Hazards
Engr. Controls
PPE
Equipment,
Tools:
Mat’ls, Supplies:
Add’l Training
Requirements
Laboratory: Multi-lab
Authored by:
Dick Sevier, Research Support Engr.
Filename:
Non-Toxic, Non-Flam Compr Gas Cyl
Chg 12-Feb-13.doc
Rm: Multi-room
Date: 12-Feb-13
Revision:
4
This procedure provides instructions on how to change non-toxic, non-flammable
compressed gas cylinders in the lab environment.
It does not cover other gases or other aspects of compressed gas cylinder safety.
explosion, mechanical, physical, slip/trip/fall, pneumatic, asphyxiation
none
safety glasses, close-toed shoes
cylinder cart with strap or chain to secure cylinder, cylinder cap, 10” or 12” open end
adjustable wrench.
cylinder status tags, lint-free cloth, “Snoop” leak detector or equivalent
none
Special Requirements:
Handling & racks for gas cylinders that allow cylinders to be restrained by chain or heavy strap at least 2/3s
Facilities up from the bottom of cylinder.
Spill & Incident
n/a
Decontamination/
Waste Disposal
n/a
TABLE OF CONTENTS
WARNINGS: ................................................................................................................................... 2
DESCRIPTION OF SYSTEM .......................................................................................................... 2
TASKS ............................................................................................................................................ 3
1. Checking Cylinder Pressure To See If Cylinder Requires Change ...................................... 3
2. Moving the Empty Cylinder from Point-of-Service to Storage Rack .................................... 3
3. Moving the Replacement Cylinder from Storage Rack to Point-of-Service ........................ 5
4. Installing Replacement Cylinder............................................................................................. 5
N2 AND AIR COMPRESSED GAS CYLINDER CHANGE
WARNINGS:
a. This is a general procedure for changing non-toxic compressed gas cylinders. Ensure that your
system is accurately represented by the one show in in this procedure. If your system differs from
the system shown, stop work immediately and consult with your lab supervisor or PI.
b. Never attempt to move a gas cylinder without the protective cap on.
c. Do not to use Teflon tape to seal threads on between the regulator fitting and gas cylinder, as this
could weaken the threads.
d. Always use the gas cylinder cart to move a gas cylinder.
e. Cylinders must be secured at all times:
 Chained to the wall rack during storage.
 Chained or strapped in position during use.
 Chained to the cylinder cart or hand truck prior to and during transport.
f. Gas cylinders are extremely heavy. Use two people if necessary to move cylinder on and off cylinder
cart.
DESCRIPTION OF SYSTEM
Regulator
Pressure
Cylinder
Pressure
Cylinder
Valve
System
Supply
Valve
Regulator
Pressure
Valve
System
Supply
Line
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Compressed
Gas Cylinder
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N2 AND AIR COMPRESSED GAS CYLINDER CHANGE
TASKS
Hazard, EC and PPE information listed below applies to the following tasks and sub-tasks
unless otherwise noted.
Hazards explosion, mechanical, physical, slip/trip/fall, pneumatic, asphyxiation
Engineering
none
Controls
PPE safety glasses, close-toed shoes
1. Checking Cylinder Pressure To See If Cylinder Requires Change
a. Confirm that the cylinder valve on the top of the cylinder
is opened by turning it counter-clockwise (when viewed
from above).
b. If the pressure reading on the cylinder pressure gauge is
below 200 psi, the cylinder is ready to be changed. Go
to the next step. Otherwise wait to change cylinder or
bleed off pressure to below 200 psi.
Pressure
< 200 psi
2. Moving the Empty Cylinder from Point-of-Service to Storage Rack
a. Close the main cylinder valve on the top of the cylinder
being changed by turning it clockwise when viewed from
above. This will close the gas feed from the cylinder.
a.
b. Decrease the pressure in the system line by turning the
regulator valve clockwise to fully close.
b.
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N2 AND AIR COMPRESSED GAS CYLINDER CHANGE
c. Make sure that both gauges on the regulator assembly read zero. If both gauges do not read zero,
use the adjustable wrench slightly loosen the regulator coupling to allow gas in the regulator
assembly to bleed off. See instructions below for loosening the regulator coupling.
d. To remove the regulator, loosed the regulator fitting that is threaded into the neck of the compressed
gas cylinder.
Note: Regulators for different gases have different thread systems and interface system, according
to the Compressed Gas Association z(CGA) specification for that gas. For example, N2, argon,
helium regulators use a right hand thread while air regulators use a left hand thread. Identify the
direction of the thread of your regulator before loosening the regulator attachment fitting. Also,
regulators may have different thread diameters and thread pitch. Consult with your gas supplier if
you are not sure what regulator is needed for your gas.
Right hand thread- Using the adjustable wrench, loosen the
regulator attachment fitting on the cylinder that is being changed
by turning in the direction shown. Turn until the regulator
assembly can be removed from the cylinder. Leave the system
supply line connected to the regulator assembly.
Left hand thread- Using the adjustable wrench, loosen the
regulator attachment fitting on the cylinder that is being
changed. Turn until the regulator assembly can be removed
from the cylinder. Leave the system supply line connected to the
regulator assembly.
RH Thread
LH Thread
e. Turn until the regulator assembly can be removed from the cylinder. Leave the system supply line
connected to the regulator assembly.
f. Hang the regulator assembly out of the way and carefully thread a
protective cap on the cylinder until the cap is fully seated.
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N2 AND AIR COMPRESSED GAS CYLINDER CHANGE
g. There should be a status card located around the cylinder neck. Tear off the “in
service” segment so that it now reads “empty”. If there is not a card already on the
cylinder, attach a new one and tear off the “full/in service” segments so it reads
“empty”.
h. Move the gas cylinder cart or hand truck close to the empty cylinder remove the safety chain and
carefully roll the empty cylinder onto the cart or hand truck. Attach the safety chain on the cart
around the empty gas cylinder.
i. Move the cylinder over to an empty space on storage wall rack space. Remove the safety chain on
the cart from the cylinder and move the cylinder into position on the storage wall rack. Attach the
safety chain on the wall rack to secure the empty cylinder to the rack.
3. Moving the Replacement Cylinder from Storage Rack to Point-of-Service
a. The replacement cylinder should already be safely stored at the storage
wall rack. Locate the appropriate replacement gas cylinder and ensure
that has a protective cap prior to handling it. Locate a cap and install if
necessary.
b. Move the cylinder cart or hand truck in place next to the gas cylinder.
c. Disconnect the wall rack safety chain and carefully load the cylinder onto
the cylinder cart. Attach the cart safety chain and move the replacement
cylinder to the empty space on the point-of-service wall rack. See photo
at right.
d. Disconnect the cart safety chain or strap and carefully move the
replacement gas cylinder into position along the point of service wall rack.
Attach the rack safety chain or strap around the replacement gas cylinder.
4. Installing Replacement Cylinder
a. Remove the protective cap from the gas cylinder.
b. Remove the plastic plug in the cylinder outlet. Wipe the outlet with a clean, dry, lint-free cloth to
remove any debris.
c. Attach the regulator assembly by carefully threading the regulator coupling into the cylinder outlet.
Recall that regulators for air cylinders have left hand thread. Tighten the fitting with the wrench until it
is snug.
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N2 AND AIR COMPRESSED GAS CYLINDER CHANGE
d. Slowly open the cylinder valve on top of the cylinder
turning in a counter clockwise direction when viewed
from above until full pressure (~2000-3000 psi) is noted
on the cylinder pressure gauge.
e. Ensure the system supply line is pressurized by opening
the system supply valve. This is done by turning the
shut-off valve knob counter-clockwise.
h.
i.
f. Set the system pressure by turning the regulator valve by slowly turning the valve counter-clockwise
until the regulator pressure gauge reads 60 psi.
g. Add a cylinder status tag around the neck of the cylinder. Remove the “full” segment
of cylinder status tag so that the cylinder reads “in service”.
h. Verify that the regulator fitting and any other fitting disturbed in this process are free of leaks using a
bottle of ‘Snoop’. Follow the instructions on the bottle.
i. Return the cart and all tools and supplies used for the gas cylinder replacement to their proper
storage.
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