This document provides an overview of compressed gas safety. It discusses the four types of compressed gases, chemical hazards associated with different gas contents, and physical hazards related to high pressure cylinders. Guidelines are presented for proper storage, transportation, use, and emergency response for compressed gas cylinders. The responsibilities of workers are also summarized, which include knowing gas contents, maintaining equipment, following safety rules, and being prepared for emergencies.
3. Learning Objectives
At the conclusion of this presentation, you will:
►Know types of gases in compressed gas cylinders
►Recognize hazards associated with these gases
►Know safe use practices of compressed gases
6. Compressed Gas Cylinders
Standard portable industrial gas cylinder:
►Stores gases at high pressures
►57in tall, 9in diameter
►One-quarter inch thickness
►About 155lbs in weight when filled
►330 cubic ft of gas at 2640 lbs per square inch
7. Four Types of Compressed Gases
Substance types in gas cylinders:
►Gas at standard temperature,
increased pressure
►Liquefies at standard temperature,
increased pressure
►Dissolved in a solvent
►Liquefies at reduced temperature,
increased pressure
8. Gas at STP
Gases at standard temperature:
►Air
►Argon
►Helium
►Nitrogen
►Oxygen
12. Hazards of Compressed Gas Systems
Hazards of use, storage, and handling of cylinders:
►Chemical hazards:
–Associated with cylinder contents
►Physical hazards:
–Due to presence of a high pressure vessel
15. Labeling and Material Safety Data Sheets
Labeling and MSDS practices:
►Cylinders may be stenciled or stamped
►Three-part tag systems
►Cylinder color-coding is unreliable
►Periodic inspections
►All gases to be included in:
– Hazard communication
chemical inventory
– Material Safety Data Sheets
16. Segregation
Compressed gases should be segregated from:
► High traffic areas
► Oil and grease
► Flames, sparks, heat, or ignition
► Electrical circuits
Cylinders should be protected from:
► Ground
► Direct sunlight
► Dampness
► Salt and other corrosives
17. Fire Protection
Cylinders containing flammable gases should be:
►Separated from cylinders containing oxidizing gas:
– 20 feet
– 5 foot fire-resistant barrier
►Stored in a well-ventilated space
►Use flow restrictors or surge protectors
18. Cylinder Leaks
Leak detection procedures:
►For flammable gas – soapy water solution
►Temperatures at or below freezing use 50%
glycerin-water
►For toxic/corrosive gas – test with inert gas
►Establish emergency procedures
21. Physical Hazards
Container may rupture due to:
►Forklift puncture
►Knocked over
Ruptured tanks
►May become projectiles
►Release toxic gas into the atmosphere
►Turn the environment flammable
22. Securing Cylinders
Gas cylinders must be secured at all times:
►In a vertical position
►Secured at 2/3 of it’s height with:
– Chain, plastic coated wire cable, or straps
►Secured individually
23. Transporting Cylinders
Rules for transporting:
►Never drag, slide, or roll a cylinder
►Always have valve cap on
►Never transport with regulator in place
►Ensure it’s secured to cart
►Do not drop or strike against objects
►Do not lift by valve cover
►Do not use ropes or slings
24. Cylinder Testing
Test information marked on cylinder:
►Hydrostatic and burst testing are most common
►Hydrostatic or ultrasonic testing is required every
5 - 10 years
1. DOT Specifications – Material or
Construction
Serial Number
2. Registered Owner
3. Date of Manufacture and original hydrostatic
test
4. Neck Ring – Current Owner
5. Retest Markings
6. Barcode
7. Cylinder Manufacturers Marking
8. TW = Tare Weight
26. Gas Lines and Piping
Guidelines:
►All gas lines should be labeled
►Hoses should be examined
►Avoid unnecessarily long hoses
►Keep hoses free of kinks
►Keep hoses away from high
traffic areas
►Repair leaks promptly
►One hose per type of gas
27. The Regulator
Precautions:
►Make sure correct regulator is equipped
►Inspect regulator and cylinder
►Never use grease or oil
►Valve handle should be easily accessible
►Use proper tools for valves
►Check MSDS
►Fire extinguishers
►Valve outlet facing away
28. Cylinder Storage
Storage area should be:
►Away from heat and ignition sources
►Designated “no smoking”
►Marked as gas storage
►Restricted access
►Provided with appropriate equipment
29. Cylinder Storage (continued)
Gas containers should be:
►Capped, stood upright, and properly secured
►Segregated according to categories
►Segregated according to full or empty
►Manage so oldest is used first
►Periodically checked for condition
30. Empty Cylinders
Proper procedure:
►Considered full until identified as empty by user
►Labeled “M T” or tagged when empty
►Empty cylinders are returned to supplier
►Leave 25 psig minimum pressure
►Do not leave empty cylinders
attached to pressurized system
32. Your Responsibilities
Your responsibilities include:
►Knowing content of cylinders used
►Regulator, valve, and hose maintenance
►Following rules for storage, transportation, and use
►Knowing what to do in an emergency
33. Additional Information
Compressed Gas Safety: General Safety Guidelines,
Montana Department of Labor and Industry
Air Products Safety Grams
http://www.airproducts.com/index.asp
Compressed Gas Association (CGA)
www.cganet.com
Compressed Gases Self Inspection
Checklist, National Institute for
Occupational Safety and Health (NIOSH)
Safety Checklist Program for Schools
Editor's Notes
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Welcome to your Compressed Gases presentation.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
We have very specific learning objectives for you during this presentation.
At the conclusion of this presentation, you will:
Understand various types of gases stored within compressed gas cylinders.
Recognize the chemicals and physical hazards associated with these gases.
Be familiar with work practices for the safe use of compressed gases in the workplace.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Our presentation today will involve the following agenda:
We will discuss the 411 on compressed gases and cylinders.
We will then review both chemical hazards and physical hazards.
We will discuss some of your responsibilities.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Section 1 will cover information on compressed gases and cylinders.
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A gas cylinder or tank is a pressure vessel used to store gases at high pressure.
Gas cylinders are typically constructed of carbon steel, stainless steel, aluminum, or composite materials.
Gas cylinders come in many sizes, depending on the application and whether the cylinder is to be portable or in a fixed location.
A standard portable industrial gas cylinder is 57 inches tall, 9 inches in diameter, has a wall thickness of about one-quarter inch, weighs about 155 pounds when filled, and contains 330 cubic feet of gas at a pressure of 2640 pounds per square inch.
Of course, there are many other sizes of portable cylinders, all the way down to the propane cylinder for a camp stove you can hold in your hand.
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There are four different types of compressed gases stored in gas cylinders.
They are as follows:
A substance that remains a gas at standard temperature but increased pressure.
A substance that liquefies at standard temperature but increased pressure.
A substance that is dissolved in a solvent.
A substance that is liquefied at reduced temperature and increased pressure.
Let’s review each type.
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The first category of compressed gases is a substance remains a gas at standard temperature and increased pressure.
Examples would include:
Air
Argon
Helium
Nitrogen
Oxygen
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
The second category includes substances that are liquids at standard temperature but increased pressure.
Examples include:
Butane
Propane
Carbon dioxide
Nitrous oxide
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
The third category includes substances that are dissolved at standard temperature in a solvent.
The most common example of this type is acetylene.
Note: Acetylene cylinders contain an inert packing material and are filled with a solvent such as acetone.
The acetylene is pumped into the cylinder and it dissolves in the solvent.
When the cylinder is opened the acetylene comes back out of solution, much like a carbonated beverage bubbles when opened.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
The fourth category includes substances that are liquefied at reduced temperature and increased pressure.
These are also referred to as cryogenic gases.
Examples include:
Liquid nitrogen
Liquid oxygen
Carbon dioxide
Note: cryogenic gases are typically equipped with some type of “bleed” device to prevent overpressure from rupturing the bottle and to allow evaporative cooling to continue.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
There are two types of hazards associated with the use, storage and handling of compressed gas cylinders:
The chemical hazard associated with the cylinder contents (such as corrosive, toxic, flammable, etc.).
The physical hazards represented by the presence of a high pressure vessel in the laboratory.
In the next sections of this presentation, we will explore these hazard categories in detail.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
In section 2, we will review chemical hazards of compressed gases
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Welcome to Section Two, where we will review chemical hazards of compressed gases.
Depending on the particular gas involved, there is a potential for exposure to considerable chemical hazards.
Gases used may be: flammable or combustible, corrosive, explosive, poisonous, inert, acidic, reactive, and a combination of hazards.
Care must be taken to avoid exposure to these gases through inhalation.
Extremely toxic gases should only be used inside laboratory hoods or ventilated cabinets.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
To avoid any confusion and to ensure safe handling, the specific contents of all compressed gas cylinders needs to be clearly identified.
Identification of the cylinder contents can be accomplished by stenciling or stamping the contents on the cylinder or on a label.
Commercially available three-part tag systems are convenient for identification and inventory.
Never rely on the color of the cylinder for identification.
Color-coding is not reliable because cylinder colors may vary with supplier.
Also, never rely on labels on cylinder caps because they are interchangeable.
Inspections should be periodically performed to ensure that the contents of all cylinders in the workplace are clear and identified.
Of course, all compressed gases need to be included in the hazard communication chemical inventory and Material Safety Data Sheets (or MSDSs) available in the workplace.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
In the workspace, compressed gases should be segregated from the following:
High traffic areas.
Oil and grease.
Flames, sparks, or any source of heat or ignition,.
Electrical circuits.
Cylinders should be protected from:
The ground to prevent bottom corrosion.
Direct sunlight.
Continuous dampness.
Salt or other corrosives.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Many gases, including a variety of organic compounds such as ethylene, propane, or methane are flammable and can turn a cylinder into a flame-thrower, if ignited.
Flammable gases can be ignited by static electricity or by a heat source, such as a flame or hot object.
Flammable gases should not be stored near unprotected electrical connections, heat sources, or any source of ignition.
Cylinders containing flammable gases (empty or full) should be separated from cylinders containing oxidizing gases by a minimum distance of 20 feet or by a barrier at least 5 feet high which has a fire-resistance rating of at least one-half hour; for example, a concrete block wall.
Storage of flammable gases in a ventilated, fire-resistant enclosure is recommended.
If this is not possible, flammable gas cylinders should be stored in a well-ventilated space.
The use of flow restrictors or surge protectors on flammable gas cylinders is recommended, in order to prevent a sudden large flow of gas if a rupture or other unexpected release happens in the system.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Leaking cylinders constitute a threat that may be so serious that entire facilities may be required to evacuate and outside help may be required to assist.
Leak detection procedures should be implemented prior to use of any system using compressed gas.
This can be accomplished in the following manner:
For a flammable gas, a flammable gas detector, a soapy water solution, or a 50% glycerin-water solution may be used.
At temperatures at or below freezing, the 50% glycerin-water solution should be used.
For systems where toxic or corrosive gases will be used, first test the system with an inert gas before introduction of the hazardous material.
Emergency procedures should be established and communicated to all personnel so that everyone knows what to do in the event of a leaking cylinder.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Engineering controls are the most effective method to control the risks associated with compressed gas use.
Common engineering controls include the following:
An emergency shutoff switch can be used at a remote location to cause pneumatic valves to shut, stopping gas flow. Switches should be non-electric so that arcs or sparks are not created around flammable gases.
Hazardous gas cylinders can be housed in a gas cylinder cabinet, which can be equipped with sprinkler protection and ventilation.
Flow restrictors can be used to limit gas flow and should be installed immediately downstream of each hazardous gas cylinder.
An emergency eyewash must be present in areas were corrosive materials or gas is used.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
In section 3, we will review the control of physical hazards associated with compressed gas cylinder usage.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Welcome to Section Three, where we will review the control of physical hazards associated with compressed gas cylinder usage.
The principal physical hazard associated with compressed gases is the rapid release of contents under pressure if the container were to rupture.
The container may rupture due to contact, such as a forklift puncturing a propane tank, or a portable cylinder may be knocked over and the valve stem cracks as a result of hitting the floor.
Of course, once an uncontrolled release of contents occurs, we’ve got some serious potential problems.
It has been reported that if a full tank were to have the valve sheered off, the projectile could travel some 500 yards and go through concrete walls.
Other problems may shortly follow, based on the nature of the gas being released.
The gas may create a toxic or flammable atmosphere, for example.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Gas cylinders must be secured at all times to prevent tipping:
Cylinders should be secured in a vertical position.
The cylinders must be secured at a point approximately 2/3 of its height, using an appropriate material such as a chain, plastic coated wire cable, or commercially available cylinder straps.
Cylinders should be secured individually, meaning one restraint per cylinder.
The issue with restraining multiple cylinders on one restraint is that in order to move one of those cylinders, all of them must be unrestrained.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
There are some very important rules to follow when transporting compressed gas cylinders:
Never drag, slide, or roll a cylinder; use a cylinder cart or basket.
Always have the protective cap covering the valve when transporting the cylinder.
Never transport the cylinder with the regulator in place.
Make sure the cylinder is secured to the cart before moving it.
Do not drop cylinders or strike them against each other or against other surfaces violently.
Do not use the valve cover to lift cylinders; they could be damaged and become unattached.
Ropes or slings should be not be used to suspend cylinders unless the gas vendor has made provisions for such lifting and attachment points are provided on the cylinder.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
There are a variety of tests that may be performed on various cylinders.
Some of the most common types of tests are the hydrostatic test and the burst test.
During the manufacturing process, vital information is usually stamped or permanently marked on the cylinder.
This information usually includes the type of cylinder, the working or service pressure, the serial number, date of manufacture, the manufacture's registered code, and sometimes the test pressure.
High pressure cylinders that are used multiple times--as most are--are hydrostatically or ultrasonically tested and visually examined every few years.
In the U.S., hydrostatic or ultrasonic testing is required either every five years or every ten years, depending on cylinder and its service.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
When gases are supplied in gas cylinders, the cylinders have a stop angle valve at the end on top.
During storage, transportation, and handling when the gas is not in use, a cap may be screwed over the protruding valve to protect it from damage or breaking off in case the cylinder were to fall over.
Instead of a cap, some cylinders have some sort of protective frame around the stop valve.
When the gas in the cylinder is ready to be used, the cap is taken off and a pressure-regulating assembly is attached to the stop valve.
This attachment typically has a pressure regulator with upstream (inlet) and downstream (outlet) pressure gauges and a further downstream needle valve and outlet connection.
The upstream pressure gauge indicates how much gas is left in the cylinder according to pressure.
The regulator could be adjusted to control the flow of gas out of the cylinder according to pressure shown by the downstream gauge.
The outlet connection is attached to whatever needs the gas supply, such as a laboratory instrument for example.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
The following guidelines apply to gas lines and hoses:
All gas lines leading from a compressed gas supply should be clearly labeled to identify the gas and the area served.
Hoses should be examined on a regular inspection schedule.
Unnecessarily long hoses should be avoided.
Keep hoses free from kinks and away from high traffic areas.
Repair leaks promptly and properly.
Do not use a single hose for multiple types of gases.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Before cylinders are first used the following precautions should be taken:
Make sure the cylinder is equipped with the correct regulator.
Inspect the regulator and cylinder valves for grease, oil, dirt, and solvent.
Never use grease or oil to lubricate regulators or cylinder valves because they can cause an explosion.
The cylinder should be placed so that the valve handle at the top is easily accessible.
When using toxic or irritating gas, the valve should only be opened while the cylinder is in a working fume hood.
Only use wrenches or tools that are provided by the cylinder supplier to open or close a valve. Pliers should never be used to open a cylinder valve. Some regulators require washers; this should be checked before the regulator is fitted.
Refer to MSDS for the gas being used for information regarding use and toxicity.
Fire extinguishing equipment should be readily available when combustible materials can be exposed to welding or cutting operations using compressed cylinder gases.
Open the valve slowly and only with the proper regulator in place.
Stand with the cylinder between yourself and the regulator (cylinder valve outlet facing away) when opening the cylinder valve.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
The compressed gas storage area should be:
Free from risk, away from sources of heat and ignition.
Designated as a “no smoking” area.
Clearly marked as a gas storage area with appropriate hazard warning signs.
Kept clear with access restricted to authorized personnel.
Provided with appropriate safety and emergency equipment, including a fire extinguisher and adequate ventilation.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Compressed gas containers placed in the storage area should be:
Capped, stood upright, and 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.
Checked periodically for general condition.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
All cylinders are to be considered full unless properly identified as empty by the user.
In many workplaces, the user writes the letter M and T (the phonetic spelling of empty) on an empty cylinder, in other workplaces tags are used.
“M .T.” cylinders should be returned to the supplier and not be permitted to accumulate.
To prevent contamination, and even explosive mixtures in cylinders, always leave at least 25 psig minimum pressure in all “empty” cylinders.
Do not leave an empty cylinder attached to a pressurized system.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
In section 4, we will review some of your responsibilities as a use of compressed gases.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Let’s review some of your responsibilities as a use of compressed gases.
As a user of compressed gases, you should:
Know the content of each cylinder you use.
Ensure regulator is proper type, valves, and hoses are in good shape.
Follow rules we have discussed for storage, transportation, and use of cylinders.
Know what to do in the event of an emergency.
Recommended Facilitator Notes: (read the following text out-loud to participants while showing this slide)
Here are some outstanding sources of additional information on this important topic for your future reference.
Compressed Gas Safety: General Safety Guidelines, Montana Department of Labor and Industry
Air Products Safety Grams:
http://www.airproducts.com/index.asp
Compressed Gas Association (CGA):
www.cganet.com
Compressed Gases Self Inspection Checklist,
National Institute for Occupational Safety and Health (NIOSH) Safety Checklist Program for Schools