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Compressed Gas Safety
University of Nebraska
EHS Lab Safety
Colloquium Series Initiative
The information and recommendations contained
herein have been compiled from sources believed
to be reliable and represent the current opinion
on the subject.
No warranty guarantee or
representation is made by Linweld Inc. as to the
correctness or sufficiency of any information
contained herein and Linweld Inc. assumes no
responsibility therewith.
The content in this
document is not to be construed as legal advice or
the final authority regarding OSHA, EPA, DOT or
any other government agencies.
When it comes to handling compressed
gas cylinders and cryogenics; there
are only three potential problems.
The Containers, The Contents And The
Pressure.
Other Than That - There Is No
Problem!
The Containers
Gas
Packs
Gas
Packs
Let’s Talk About The Container
Handling Compressed Gas Cylinders
o Never use cylinders as rollers.
o Never lift a cylinder by the cap.
o Never move or transfer cylinders
without their caps.
o Never allow cylinders to be exposed
to flame or extreme temperatures.
o Never tamper with valves.
Cylinder Securement
o All compressed gas cylinders MUST
be secured from falling at ALL times.
o Use a chain or other substantial
restraint devices whether
or not the cylinders are in
storage or in use.
29CFR 1910.101(b) & CGA 3.7.4
Visually Inspect All Cylinders
o Watch for asymmetrical ice patches on
the side of the cylinder.
o Watch for excessive ice build up on
the pressure relief valves.
o Arc burns, excessive heat, corrosion
and gouges are a few things that can
weaken the walls of a cylinder.
Protect Valves
o Use caps on all cylinders that are able
to receive a cap except when
connected for use.
o Any cracked or dented caps should be
brought to the attention of your
Linweld Representative.
29CFR 1910.101(a) & CGA 3.4.1
Gas Regulators
o Regulators are designed to reduce
compressed gas pressures to usable
pressures.
o Regulators come in high & low
pressure designs.
o Incorrectly exchanging or
interchanging regulators can have
catastrophic consequences.
Gas Regulators
o Compressed Gas Regulators are
sophisticated and exact
metering devices that are
required to be used and
maintained according
to manufacturer
recommendations.
Gas Regulators
The internal working parts of the regulator are precision units. Only qualified
technicians should clean or repair a regulator
The low pressure gauge
indicates the delivery
pressure to the hoses &
torch
The Pressure adjusting screw
turning clockwise allows the
gas to flow turning counter
clockwise reduces or
stops the gas flow
The High pressure gauge
Indicates the pressure
from tank
The inlet connections More just right & left
hand thread regulators
and connectors are
specific to their
application.
Keep free of oil, grease,
& dirt
Gas Regulators
Potential Hazards
Interchanging gas regulators has several
potentially hazardous outcomes.
o The density and the viscosity of various
gases change their flows through flow
meters. Thus interchanging flow meters
between different gases may result in
inaccurate readings. The 02 flow meter is
not accurate with Helium, or with air.
Gas Regulators
Potential Hazards
Interchanging gas regulators has several
potentially hazardous outcomes.
o Different gases have different effects with
the internal components of the various
regulators. Some gases can deteriorate
the diaphragms and other working parts.
Gas Regulators
Handling & Use
o Regulators are gas specific and not
necessarily interchangeable!
o Always make sure that
the regulator and valve
fittings are compatible.
o Never use adapters beyond
manufacturers recommendation.
Gas Regulators
Handling & Use
o After the regulator is attached, the
cylinder valve should be
opened just enough to
indicate pressure on
the regulator gauge
(no more than one full
turn) and all the connections checked with
a soap solution for leaks.
Gas Regulators
Potential Hazards
Interchanging gas regulators has several
potentially hazardous outcomes.
o Oxidizing, Flammable, Toxic, Corrosive and
Strong Oxidizing gasses are incompatible
and auto-reactive. Even trace amounts in
the regulators or gas lines could have
potentially catastrophic results.
Gas Regulators
Potential Hazards
o Further information can be found in
ANSI/CGA V-1-1994 ‘Standard for
Compressed Gas Cylinder Valve Outlet and
Inlet Connections”.
o UNL SOP http://ehs.unl.edu
The Contents
Hazardous Material is any material
known to create a danger to any
person’s health, life, or property through
contact, exposure, inhalation, fire,
explosion or environmental pollution.
All compressed & cryogenic gases are
considered Hazardous Materials.
The Contents
Content Identification
All compressed gas cylinders are required to be
identified as to their contents.
OSHA Required Components
Product name
Precautionary statement
Responsible company
Always check the cylinder label; NEVER rely on the
color of a cylinder as to its contents.
The Contents - Types of Hazards
Toxic
Irritation
Flammable
Sensitization
Carcinogenic
Explosive
Reactive
Biological
Radioactive
Corrosive
Teratogenic
Mutigenetic
The Contents
Cryogenic Liquids
Gases stored as liquids at temperatures
below -130o F.
Helium /-452o F
Nitrogen /-320o F
Argon /-302o F
Oxygen /-297o F
The Contents
Non-Cryogenic Liquids
Gases stored as liquids at temperatures
above -130o F.
Nitrous Oxide / -127o F
Carbon Dioxide / -109o F
Propane / -44o F
Anhydrous Ammonia / -28o F
Lack of correct PPE and exposure
to Liquid Propane
The Contents
Low Temperature Hazards
o
o
o
o
o
Never allow liquids to contact skin or eyes.
If exposed, warm area with warm water.
Make a medical referral.
Oxygen Displacement
Can cause asphyxiation
The Contents
Health Hazards
Central nervous system
o Anoxia
o Direct action on neurons
Target organ effects
o Liver
o Kidneys
o Blood
o Reproductive system
The Contents
Explosive Hazards
Flammable Limits (in Air)
0%
LEL
TOO LEAN
100%
UEL
FIRE OR EXPLOSION
TOO RICH
Acetylene /LEL 2.2% - UEL 82.5%
Hydrogen /LEL 4.0% - UEL 74.5%
Propane / LEL 2.2% - UEL 9.5%
The Contents
Oxidizers
o
o
o
o
Supports combustion.
Do not use near oil or grease.
Never refer to oxygen as “air”.
Liquid oxygen can saturate clothing,
making them flammable.
o Keep 20ft away or separated by a ½ hour
rated fire resistant wall from flammable
materials.
The Contents
Explosive Hazards
Fire Triangle & Fire Tetrahedron
OXYGEN
UNINHIBITED
CHEMICAL
REACTION
HEAT
FUEL
The Contents
Handling & Storage
Personal Protective Equipment
Gloves
Eye Protection
Face Protection
Clothing and Coverings
Atmospheric Monitoring
The Contents
Hazards
Temperature
Weight
Rapid Vaporization
Pressure
Oxygen Displacement or
Enrichment (CO2 is a vasodilator)
The Pressure
Expansion Rates
Besides the contact of cryogenic liquid with
human tissue there is the rapid vaporization
that must be taken into account.
Coffee Cup Illustration
 One cup of Liquid Oxygen at an expansion rate
of 860:1 will produce 649 cubic feet of gas.
 One cup of Liquid Nitrogen at an expansion
rate of 696:1 will produce 600 cubic feet of gas.
 One cup of Liquid Argon at an expansion rate of
841:1 will produce 512 cubic feet of gas.
The Pressure
Asphyxiation
Let’s Talk About The Pressure
What does
1/2 pound
of Dynamite
look like?
Cylinder Force - Don’t Make A
Rocket, Man.
The compression of gases is similar to the compression of a spring,
the greater compression the greater the release of the stored
energy there is. However, unlike a spring in which the energy is
released in the opposite direction that it is compressed. Gases do
not have a shape, and when accidentally released; releases its
stored energy in all directions.
A “K” size nitrogen compressed to 2200 pounds per square inch,
has the stored energy equivalent to a half pound of TNT!
If there was an uncontrolled release of energy such as a valve
being sheared off, or the cylinder failed in some way, you would
have a rocket or a bomb. Both are undesirable options.
Thanks to Don L Wenzl, LINWELD Specialty Gas Technician
Other Safety Concerns
o Compressed gas streams should never be
directed toward any person. CGA 3.3.10
o Federal Standard: compressed air shall not
be used for cleaning purposes except
where reduced to less than 30 p.s.i. and
then only with effective chip guarding and
personal protective equipment. 1910.242(b)
o Always keep the regulator free of oil,
grease and other flammable substances
o Use the correct regulators for the specific
gas service.
o Never hammer or use ‘cheater bars’ when
connecting or disconnecting regulators or
manifold connections.
o Never ‘tape’ or attempt to ‘wrap’ any
leaking connections.
o DO NOT change the inlet connection on a
regulator in an attempt to use the
regulator for a different gas service.
o Never stand in front or behind a regulator
when opening the cylinder valve.
o Identify ‘full’ & ‘empty’ cylinders and
maintain proper seperations.
The scrapper’s pickup truck on which the
Oxygen GP was being transported.
The pressure relief devices had been removed
and plugged using a threaded cap
Cylinder exploded at 12:40 PM while transport
vehicle was parked on busy Interstate highway
Vehicle Location
Cylinder Trajectory
The blast blew one individual across 5 lanes of traffic.
The other was blown approximately 40 feet.
Both men survived
Cylinder flew approximately ¼ mile before plunging through
the roof of an apartment, severing a main natural gas line and
coming to rest in the living space
Plywood applied over hole in roof
Despite heavy damage, no injuries to
apartment tenants were reported
Apartment interior
Note that the media reported the event as a
Butane cylinder explosion
Monday the 29th of September, 2003, a fitter with a work van
left an E size Oxygen and Acetylene cylinder on the back seat of
a Toyota dual cab over the weekend.
This van was destroyed by an explosion from a carbon dioxide
cylinder that was allowed to be over-heated
.
This is an example of why cylinders need to be correctly secured
while being transported.
Conclusion
The Conclusion
o Always ensure the safety of yourself & those
around you before starting any job.
o Never ‘look the other way if you see something
that is unsafe.
o Safety is a Personal Issue … Safety is all about
YOU!
The Conclusion
Additional Information

MSDS
 Compress Gas Association (CGA)
 Pamphlet P-39, Oxygen-Rich Atmosphere
www.cganet.com
 UNL EHS Safe Operating Procedures
 http://ehs.unl.edu
Your Linweld Representative