Equipment personnel who
spend significant time moving or handling gas containers should be
- protective footwear,
e.g. steel cap shoes
- heavy gloves
- hand cart or other
suitably designed device for transporting containers and a chain
or another method for securing the container while it is being
Most accidents and injuries involving compressed gases occur during
the moving or handling of the gas container. Personnel should be
instructed in the following key points:
- remember the mass of
- beware of trapping
fingers between containers while they are being moved
- when it is necessary
to lift heavy containers manually, seek help and to observe the
correct lifting posture
- use a cylinder hand
cart or other suitable device for transporting heavy containers,
even for short distances, and ensure the container is secured
- ensure valve
protection devices, e.g., caps, guards, etc., are fitted to
containers while they are being moved
Usage area should be:
- well ventilated
- arranged so as to
minimize fire risk in the vicinity of the gas containers. It
may also be necessary to eliminate ignition sources, for example
where flammable gases are used for non-combustion applications and
where there is a risk of leakage
- provided with
appropriate safety and emergency equipment, e.g., fire
extinguishers, breathing apparatus, eye protection, etc. For
a better understanding of the usage/storage area check with the
local fire code for compliance
SwageLok and similar
fittings must be installed by competent personnel. See
Installers' Pocket Guide. Contact Purdue JAFCI
for advice or assistance.
containers should be:
- standing upright
(valve up, >45o from horizontal unless designed
specially for use in horizontal position).
- properly secured with
approved cylinder support, individually if not capped. No
uncapped cylinder should be secured to a cart, and no cylinder
cylinder secured to a cart should be uncapped.
- checked to contain the
correct gas in the designated usage area and properly secured to
prevent falling over or other movement which could fracture the
- leak tested around the
valve and valve outlet connection
- fitted ONLY with the
appropriate compatible regulator -- no adaptors.
be familiar with:
- the identification of
the gas container contents and the potential hazards. They
should also have access to the appropriate Material Safety Data
- the operation and use
of the safety and emergency equipment where provided, e.g., fire
extinguishers, breathing apparatus, eye protection, ventilated gas
- the gas container and
its valve, including the procedures for rectification of leakages
at the valve gland (where appropriate) and outlet connection.
- the correct operation
of the gas flow and control equipment including purging procedures
- the importance of
ensuring that the gas container is not contaminated by a backfeed
from the process
important to observe all handling precautions, and to use the correct
pressure and flow control equipment. The choice of suitable
equipment is dependent on the gas supply pressure, the chemical and
physical properties of the gas, the gas purity, and other users'
- Installations handling
flammable gases should be grounded to minimize the risk of sparks
due to static discharge. Flash arrestors should be used
- Installations handling
hygroscopic corrosive gases such as anhydrous hydrogen chloride
must be provided with a means of purging. An adequate device
or control to prevent the backfeed of liquids, gases or other
contaminants into the container must also be incorporated.
- Before using the gas,
read all label information and the data sheets associated with the
use of that particular gas.
- Before attaching
cylinders to a connection, be sure that the threads on the
cylinder and the connection mate, and are of a type intended for
- The threads and mating
surfaces of the regulator and hose connections should be cleaned
before the regulator is attached. Wipe the outlet with a
clean, dry, lint-free cloth. Particulate can clog the
regulator filter (if so equipped) or cause the regulator to
- Always use the proper
regulator for the gas in the cylinder. Check that the CGA
numbers match, and always ensure that the regulator appears sound
before attaching it to a cylinder. If the connections do not
fit together readily, the wrong regulator or a defective regulator
is probably being used.
- Attach the regulator
securely with the secondary valve closed and preferably with the
regulator flow backed off (counterclockwise) before opening the
cylinder valve wide.
- Do not permit oil or
grease to come in contact with cylinders or their valves, or with
regulators or flow controls. Oil or grease should especially
be avoided with containers of oxidizing gases.
- Cylinders containing
oxygen or oxidizing gases, e.g., chlorine, (empty or full) should
be separated from cylinders containing flammable gases by a
minimum distance of 20 feet or by a barrier at least 5 feet high
having a fire-resistance rating of at least one-half hour, e.g., a
concrete block wall. 3.Do not store oxidizing gases near
flammable solvents, combustible materials or near unprotected
electrical connections, gas flames or other sources of ignition.
- Always use a cylinder
wrench or other tightly fitting wrench to tighten the regulator
nut and tube connections. Use "backup" wrenches to
minimize stress on tubing and fittings where appropriate.
- Teflon tape
should never be used on cylinder connections or tube-fitting
connections. Use Teflon tape only on pipe threads where
the seal is made at the threads. All other connections have metal
to metal face seals or gasket seals.
- Open cylinder valves
SLOWLY. Point the valve opening away from yourself and other
persons. Never use a wrench or hammer to open or close a hand
wheel type cylinder valve. If the valve is frozen and cannot be
operated by hand, return the cylinder to the vendor.
- Before a regulator is
removed from a cylinder, close the cylinder valve and release all
pressure from the regulator.
- Never completely empty
a "rented" gas cylinder, rather discontinue use of the
cylinder when it has at least 25 psi remaining. Mark the
cylinder so that others know that it is nearly empty, e.g., write
"approx 25 psig remaining -- MT" on a piece of tape and
stick it on the cylinder. Close the valve and secure the
cylinder valve protective cap and outlet cap or plug, if used.
CORRECT LABELING AND
PROPER FITTINGS ON COMPRESSED GAS CONTAINERS
CGA Safety Bulletin 10-998
It is essential that any
person handling a container of compressed gas or cryogenic liquid be
certain of the contents before the container is connected to a system.
Discharging a gas or cryogenic liquid into a system not intended for
the material could cause a fire, explosion, equipment failure, gas
leak, or other hazard resulting in a serious or fatal injury.
Before attempting to
connect a container to a system, be certain of the following:
- Personnel using the
container are trained and knowledgeable regarding the product,
container, fittings, equipment, and proper connection procedures.
- The container is
clearly and properly marked or labeled with the identification of
the contents, and there are no conflicting markings, labels, or
coloring. Do not rely solely on the color of the container to
identify the contents. If there is any conflict or doubt about the
contents, do not use the container.
- The labeled contents
are the correct product for use in the system.
- The container has the
proper outlet connection(s) for its contents according to ANSI/CGA
V-1, American National, Compressed Gas Association Standard for
Compressed Gas Cylinder Valve Outlet and Inlet Connections .
- The connection(s) on
the container and the system fit together properly without being
too loose or too tight. A proper connection will go together
smoothly. Do not use adapters or excessive force.
See CGA P-1, Safe
Handling of Compressed Gases in Containers, and CGA C-7, Guide to the
Preparation of Precautionary Labeling and Marking of Compressed Gas
Containers, for additional information [2, 3].
-  ANSI/CGA V-1
American National, Compressed Gas Association Standard for
Compressed Gas Cylinder Valve Outlet and Inlet Connections,
Compressed Gas Association, Inc., 1725 Jefferson Davis Hwy., Suite
1004, Arlington, VA 22202.
-  CGA P-1, Safe
Handling of Compressed Gases in Containers, Compressed Gas
Association, Inc., 1725 Jefferson Davis Hwy., Suite 1004,
Arlington, VA 22202.
-  CGA C-7, Guide to
the Preparation of Precautionary Labeling and Marking of
Compressed Gas Containers, Compressed Gas Association, Inc., 1725
Jefferson Davis Hwy., Suite 1004, Arlington, VA 22202
Empty containers are not
really empty. They contain gas at atmospheric pressure, which of
course does not cause deflection of the gauge needle because the gauge
reports psig, the pressure greater than atmospheric. In
abosulte terms the cylinder still contains approxiamtely 15 psia
(pounds per square inch absolute). Depending on cylinder size,
this can be a substantial quantity of toxic or flammable substance.
It is important to ensure
that gas containers are in a safe condition after use. Before
returning empty gas containers, a check should be carried out to
- the container valve is
closed and not leaking
- the container valve
outlet plug or cap nut, when supplied, has been securely refitted.
This is particularly important if the contents of the container
- the container valve
protection device is properly fitted
The most effective action in an emergency situation will result from
careful prior planning. The following checklist identifies some of the
key factors that should be considered:
- Is there a properly
documented and practiced emergency procedure?
- Are personnel properly
trained in the product properties and the use of emergency
- Has the Fire
Department been advised of the products used on site and their
- Is there a properly
trained team of technicians on site to deal with emergency
- Have the local medical
services been advised of the products handled on site and are any
specialized medical requisites readily available?
- Is there adequate
emergency equipment readily available, and are people trained in
compressed gases are unlikely, provided the recommendations are
followed for their correct storage, handling, and use. When problems
do arise they are usually due to:
- Fire threatening the
cylinder: The compressed gas container is a high integrity
package. However, if it comes in contact with excessive heat for
prolonged periods, then there is a risk of rupture and explosions.
- Flammable gas leak:
All flammable gases will form explosive mixtures with air. When
ignited, significant explosive energy can be released from
flammable gas-air mixtures.
- Toxic gas leak: Safe
working limits are prescribed by the Material Safety Data Sheets.
Where proper facilities and equipment are provided, personal
injury from exposure to toxic gas is extremely unlikely.
- 'Inert' gas leak: This
is usually considered to be harmless. However, if in a confined
space, asphyxiation (oxygen starvation) of unprotected personnel
- Unplanned chemical or
other reaction: This can arise when gas users allow process
material back into the gas supply cylinder and can possibly result
in rupture or explosion. It can also arise if the gas cylinder
content is mistakenly identified. This type of emergency is
extremely unlikely where operational procedures are properly
controlled and staff are properly trained.
Dealing with Fire
- General: If possible,
isolate gas supplies into affected area, and safely release the
gas pressure in affected pipelines and equipment.
- Fire threatening
compressed gas containers: There is a risk of a rupture or
explosion of cylinders subjected to prolonged heating (such as in
a fire). Such cylinders should be moved to a safe place before
they become too hot. If this is impossible, cool cylinders with
water hosed from a safe distance. Any cylinder that has been
involved in a fire must be clearly marked as such, and the
supplier must be notified accordingly.
- Ignited flammable gas
leak: If possible, isolate the gas supply. If this is impossible,
try to ensure the flammable gas burns in as controlled a manner as
possible, does not ignite anything else, and does not impinge on
any pressurized gas containers, equipment, or pipelines.
- Never extinguish a
flammable gas leak without stopping the flow of gas, because a
potential explosion hazard would result.
Dealing with gas
- General: Assess the
likely effects of the gas leakage and the affected area. This will
determine the subsequent emergency action taken and the level of
personnel protection needed.
- Leaking cylinder: Most
leaks occur at the valve fitted into the top of the cylinder.
Leakage areas that may be involved are:
- Valve outlet
connection: Leakage here is frequently due to dirt in the
connection, or damaged connections or washers where required.
Such leaks are easily rectified.
- Valve stem (i.e.,
around valve operating spindle): Leakage from valves fitted
with an adjustable gland can easily be cured by gently
tightening the gland nut while the valve is partially open. A
quarter turn is normally sufficient (maximum torque: 50
ft-lbs). All gland nuts have "right-hand" threads.
Some gland nuts are backed with a lock-nut (which must be
loosened before gland nut adjustment and tightened
- Joint between
cylinder valve and cylinder: Leakage here is extremely rare
and where it does occur, is normally identified and rectified
by the cylinder filler. No attempt should be made to tighten a
cylinder valve into a full cylinder. Such cylinders must be
set aside for the attention of the supplier.
- Valve closure:
Leakage from a cylinder valve that will not readily shut off
can usually be reduced by careful application of a greater
closing torque (using a wrench or other means of greater
leverage). All defective cylinders should be clearly labeled
before being returned to the supplier.
- Leaking gas control
equipment/pipelines, etc: Isolate the gas supply. Before
attempting to repair leaking equipment, ensure that the pressure
has been released and the equipment purged to remove all hazardous
These refer to cylinders in
storage, i.e. not in use or attached to equipment or
Storage area should be:
- free from risk, away
from sources of heat and ignition
- designated as a
"no smoking" area (not necessary if building is
smoke-free and posted as such)
- clearly marked as a
gas storage area with appropriate hazard warning signs such as
flammable, oxidizer, etc.
- kept clear with access
restricted to authorized personnel
- provided with
appropriate safety and emergency equipment, including a fire
extinguisher, adequate ventilation, etc. Check the local fire code
for compliance requirements
Compressed gas containers
in storage should be:
- stood upright
- properly secured with
approved cylinder support
- segregated according
to their various categories, such as flammable, oxidant, etc., and
providing 20' between incompatible gases
- segregated in the
storage area according to whether cylinders are full or empty
- managed to ensure that
the oldest stock is used first (individual labs may not store more
than one each of any cylinders of flammable or toxic gases)
- checked periodically
for general condition
in adjacent work areas should be:
- familiar with the
operation and use of the safety and emergency equipment provided,
e.g., fire extinguishers and alarms, main shut-offs, local exhaust
- familiar with the
hazards of the products stored