Outline

This training is intended to provide faculty, staff, and students with a general understanding of safety issues associated with compressed gas cylinders. The following topics will be covered:

• Mechanical Hazards and Safe Work Practices
• Chemical Hazards and Identification of Compressed Gas
• Cylinder Storage
• Cylinder Inspection and Connections
• Safe Operating Practices and Emergency Response

Purpose

The purpose of this training is to prevent personal injury or damage to University facilities when personnel are using compressed gas.

Without proper use and care, compressed gas cylinders can cause injury to workers and destroy equipment.

Careful procedures are necessary for handling the various compressed gases, cylinders, regulators or valves used to control gas flow, and the piping used to confine gases during flow. This training provides guidelines for the safe use of compressed gas.

Mechanical Hazards

All compressed gas (CG) cylinders and systems should be considered serious potential mechanical hazards. When neither handled safely nor contained in properly designed and maintained vessels, any of these gases can cause catastrophic mechanical failures with severe and lethal consequences.

Mechanical Hazards

• Valve shear - can cause CG cylinders to become uncontrolled and lethal projectiles
• Explosive release of the contents - may be caused by mechanical shock or damage to cylinders such as toppling, heating, denting, corrosion or electrical arcs
• Crushing injury- can easily occur if heavy cylinders are allowed to fall or roll

Working Safely

CG cylinders and systems may only be handled and operated by personnel who are trained and knowledgeable in the associated mechanical and chemical hazards and safe work practices.

Personnel must use appropriate personal protective equipment (PPE), which at a minimum should always include eye protection, when working on or around CG systems or storage areas.

An O₂ pressurized bomb calorimeter failed at about 400 psig due to rapid pressurization that lead to metal fatigue during an experiment in an FSU teaching laboratory. Luckily, no one was injured and the attached cylinder was secured. These types of incidents make it very obvious that anyone working near a pressurized system needs protection.

Working Safely

When working with CG the following safe work practices should be followed:

• Ensure cylinder valves are closed and protective caps are installed (hand tight) when not in use or before moving.
• Use a specifically designed trolley, cart, or hand truck for transporting cylinders.
• Always store cylinders in their designed upright position.
• Never refill a cylinder, use it for storage of non-intended material, or allow it to be connected to manifolds that are not designed and constructed to prevent cross-contamination. These practices have had fatal results.
• Always return cylinders to CG vendors for refill or service. Inform the vendor if you believe that the cylinders may have been contaminated or damaged.
• Never lift a cylinder by the protective cap or use improvised tools (screwdrivers, pipe wrenches, etc.) to free a stuck cap. If any tool is needed, only strap wrenches or specially designed cap tools should be used with a minimum amount of force applied.

Mythbusters Demonstration

USDA Incident Report

Six 220-cubic foot cylinders, part of a fire extinguishment system, had been moved away from their wall supports to allow painters to complete the painting of the area. While moving them back into position, it was noticed that one cylinder was leaking. The painter had the cylinder leaning against his shoulder and was attempting to scoot it across the floor. At this time, the valve separated from the cylinder and was projected backward hitting the side of a stainless steel cabinet.

The man suddenly found himself with a jet-propelled 215 pound piece of steel. He wrestled it to the floor, but was unable to hold it. The cylinder scooted across the floor hitting another cylinder, knocking it over and bending its valve. The cylinder then turned 90 degrees to the right and traveled 20 feet where it struck a painter's scaffold causing a painter to fall 7 feet to the floor. After spinning around several times, it traveled back to its approximate starting point, where it struck a wall.

At this point, the cylinder turned 90 degrees to the left and took off lengthwise of the room chasing an electrician in front of it. It crashed into the end wall 40 feet away breaking four concrete blocks. It turned again 90 degrees to the right, scooted through a door opening, still chasing the electrician. The electrician ducked into the next door opening, but the cylinder continued its travel in a straight line for another 60 feet, where it fell into a truck well striking the truck well door. The balance of the cylinder pressure was released as the cylinder spun harmlessly around in the truck well area.

The painter who fell from the scaffold received multiple fractures of his leg.

Source: http://www.ars.usda.gov/Services/docs.htm?docid=14598&page=2 ;accessed 11/12/2010

Summary

In this lesson you learned about mechanical hazards and safe work practices. Let's review the key points from this lesson:

All compressed gas cylinders and systems have mechanical hazards associated with valve shear, explosive release of contents, and crushing injuries.

Only trained personnel should handle CG cylinders.

Safe work practices should be followed when working with CG cylinders.

Checkpoint

When using CG, which of the following are considered Mechanical Hazards?

1. Valve shear
Incorrect. Valve shear, explosive release of cylinder contents, and crushing injury are all considered Mechanical Hazards
2. Explosive release of cylinder contents
Incorrect. Valve shear, explosive release of cylinder contents, and crushing injury are all considered Mechanical Hazards
3. Crushing injury
Incorrect. Valve shear, explosive release of cylinder contents, and crushing injury are all considered Mechanical Hazards
4. All of the above
Correct. When using compressed gas, valve shear, explosive release of cylinder contents, and crushing injury are all considered Mechanical Hazards

Checkpoint

When working on or around CG systems or storage areas, at a minimum, which personal protective equipment should always be used?:

1. Steel toe boots
Incorrect. Steel toe shoes or boots are not required when using compressed gases unless there is the potential for heavy objects to be dropped on feet such as when moving or handling compressed gas cylinders. Safety glasses or goggles are always required.
2. Hard hat
Incorrect. Hard hats are required when working in areas where you could strike your head on an overhanging object or there is the potential for a falling object to strike the head. Safety glasses or goggles are always required.
3. Respirator
Incorrect. In general the use of respirators should not be required. However, depending on what gas or gases are being used there may be some instances when this is true. Safety glasses or goggles should always be used.
4. Safety glasses or goggles
Correct. Safety glasses or goggles should always be used when working with compressed gas.

Checkpoint

CG cylinders may be reused/refilled to store non-intended material if it is only for a short time period.

• True
Incorrect. Never refill a cylinder, use it for storage of non-intended material, or allow it to be connected to manifolds that are not designed and constructed to prevent cross-contamination. These practices have had fatal results.
• False
Correct. Never refill a cylinder, use it for storage of non-intended material, or allow it to be connected to manifolds that are not designed and constructed to prevent cross-contamination. These practices have had fatal results.

Chemical Hazards

The chemical hazards of each gas or mixture must always be considered. With the exception of air, these always include flammable, oxidizer, corrosive, irritant, poison, toxic, reactive, or asphyxiant properties.

Contents Identification

To know the chemical hazards of the particular gas you will be using, be sure to consult the Safety Data Sheet (SDS), other vendor literature, industry recognized standards, or contact EH&S for assistance.

Safety data sheets are available on:

• FSU online SDS database
• Chemicalsafety.com

Contents Identification

The exact chemical name and concentration must be clearly identified on each cylinder. This should be stenciled or stamped on the cylinder or labeled near the valve end.

Commercially available three-part tag systems should be used for inventory information and may aid in chemical identification.

Contents Identification

Industry, government, and military agencies have all published official color coding schemes. These are not uniform and should never be relied on to identify cylinder contents; see the examples illustrated below. Never trust cylinder color schemes and never paint cylinders that you do not own. Painting cylinders for identification or maintenance should be left to professional distributors.

Click on the cylinders below to see why!

This group of 5 are standard color codes specified for oxygen. Solid green has also been specified for argon

These 3 are recent color schemes used for hydrogen. Yellow is also used for chlorine gas and red for fire suppression agents

Summary

In this lesson you learned about chemical hazards and identification of CG. Let's review the key points from this lesson:

To learn about the chemical hazards of a particular gas consult the SDS, other vendor literature, industry standards, or contact EH&S for assistance.

Never rely on cylinder color schemes when identifying its contents.

Prior to using a compressed gas, always read the label on the cylinder.

Checkpoint

Before using a CG the following properties must be considered (with the exception of air): flammable, oxidizer, corrosive, irritant, poison, toxic, reactive, and asphyxiant.

• True
Correct. Each of these properties must be considered prior to using a particular gas.
• False
Incorrect. To prevent injury while using a compressed gas all of these properties must be considered.

Checkpoint

Since industry, government, and military agencies have all published official color coding schemes it is ok to trust these.

• True
Incorrect. Never rely on cylinder color schemes. Incorrect assumptions can be deadly.
• False
Correct. Never rely on cylinder color schemes. Read the label stamped on or attached to the cylinder.

General Cylinder Storage

• Cylinders must be secured to a stationary object with a chain or strap to prevent toppling.
• Do not gang together large groups of cylinders (maximum 4 cylinders).
• "In-use" cylinders must always be secured. Do not gang these unless you cap them before unsecuring the group.
• Cylinder valves must be closed and protective caps shall be installed on CG cylinders valves that will not be used for extended periods.

In this photo, cylinders are chained but too many are ganged together. Would this arrangement adequately prevent toppling? Also, flammables and oxidizers are not segregated and "in-use" cylinders are not individually secured. Is the transfer tubing compatible with flammable gas…? There is much room for improvement.

In this photo, cylinders are not secured and far too many are ganged together…along with several other potentially serious problems!

General Cylinder Storage

Store cylinders by compatibility, i.e. oxidizers should not be stored with flammables. State law requires that flammables & oxidizers must be separated by a 30-minute rated fire barrier or by 20 feet.

General Cylinder Storage

• Cylinders containing flammable gases should not be stored near hazards such as open flames, heat sources, electrical outlets, or oxidizers
• Store all gases away from doorways and emergency exits
• Store full and empty cylinders separately and label them accordingly
• Store cylinders out of direct sunlight, away from high traffic areas, at temperatures < 125°F, and protected from corrosive environments (i.e. – salt, chemicals or standing in water)

Laboratory Cylinder Storage

Laboratory Cylinder Storage

Lecture bottle sized cylinders of gases with an NFPA health hazard rating of 3 or 4, or a rating of 2 without physiological warning properties, and pyrophoric gases must be stored and used in a mechanically ventilated hood or enclosure.

These are lecture bottles (approximate size is 2” x 13”). A maximum of 25 are permitted to be stored in each laboratory unit.

Laboratory Cylinder Storage

• Cylinders of all gases that are greater than lecture bottle size with an NFPA health hazard rating of 3 or 4, or with a health rating of 2 without physiological warning properties, must be stored in an approved continuously mechanically ventilated gas cabinet.
• Pyrophoric gas cylinders larger than lecture bottle size require the gas cabinet to also be sprinklered.

High Hazard Gas Safety

• EH&S must be contacted before any work begins with highly toxic gases (e.g. arsine, diborane, methyl bromide, nitric oxide, nitrogen dioxide, phosgene, phosphine), extremely flammable, reactive, or pyrophoric gases (e.g. silane, phosphine)
• Gases with highly hazardous properties require adherence to special building and fire codes.
• See 29CFR1910.119 App A, for more information

Summary

In this lesson you learned general and specific storage requirements of CG cylinders. Let's review the key points from this lesson:

All CG cylinders must be properly stored. When storing CG cylinders, the location must address toppling hazards, intended use, and contents (compatibility issues).

Cylinders should never be stored near doorways or emergency exits.

If you will be using a highly toxic gas, you must contact EH&S before any work begins.

Checkpoint

When CG cylinders are in use they are not required to be secured.

• True
Incorrect. Cylinders must be secured to a stationary object with a chain or strap to prevent toppling.
• False
Correct. Cylinders must always be secured to prevent toppling.

Checkpoint

CG cylinders of all gases that are greater than lecture bottle size with an NFPA health hazard rating of 3 or 4, or with a health rating of 2 without physiological warning properties, must be stored in which of the following:

1. Fume hood not being used for any other purpose
Incorrect. The cylinder must be stored in an approved continuously mechanically ventilated gas cabinet. If the contents of a CG cylinder are pyrophoric the gas cabinet must also be sprinklered. Fume hoods should not be used for storage.
2. Storage closet that is lockable
Incorrect. The cylinder must be stored in an approved continuously mechanically ventilated gas cabinet. If the contents of a CG cylinder are pyrophoric the gas cabinet must also be sprinklered.
3. Loading dock area that is access controlled
Incorrect. The cylinder must be stored in an approved continuously mechanically ventilated gas cabinet. If the contents of a CG cylinder are pyrophoric the gas cabinet must also be sprinklered.
4. An approved continuously mechanically ventilated gas cabinet
Correct. The cylinder must be stored in an approved continuously mechanically ventilated gas cabinet. If the contents of a CG cylinder are pyrophoric the gas cabinet must also be sprinklered.

Cylinder and System Inspection

• CG cylinders and systems should be observed before and during use to ensure that they are in good working condition. They must be taken out of service whenever unsafe conditions are observed.
• OSHA laws state that “each employer shall determine that compressed gas cylinders under his control are in a safe condition to the extent that this can be determined by visual inspection…visual and other inspections shall be conducted in accordance with Compressed Gas Association” See the NIOSH Self Inspection Checklist, or contact EH&S to obtain an inspection checklist that meets these requirements.
• Modifications to CG systems, cylinders, regulators or the use of items such as adapters, fittings, or lubricants not specified by the gas supplier or system designer should never be done.

Cylinder Inspection

• All cylinders must have semi-permanent labels or stamped markings indicating that they have been manufactured and inspected per US Department of Transportation (DOT or ICC), Transport Canada (TC or CTC), or United Nations (UN) standards.
• If this marking or label is not present or is unreadable, DO NOT USE THE CYLINDER and contact EH&S or the CG vendor for assistance.

In this photo, you may see that this is a DOT Type 3AA steel cylinder rated for 2400 psig maximum working pressure (at 70F), originally manufactured by the Linde Company and first hydrostatically tested in July 2006.

Note that the current contents (Nitrogen) are clearly identified on a shoulder label.

This type of cylinder cannot be refilled unless there is a date stamped for hydrostatic testing completed within the last 5 years (10 years if stamped with a star symbol).

Cylinder Identification and Markings

Source accessed 9/16/2019

Recently the DOT allowed the use of UN cylinders, you may encounter cylinders marked in metric units

Cylinder Integrity Tests

• Refillable cylinders will be marked by authorized testing facilities with the pressure test date (month and year)
• Cylinders can be used for a specified period (usually 5 years) beyond that date, however old and unused cylinders need to be returned to the vendors or disposed of by EH&S

Pressure Regulators

Pressure Relief Devices

• All cylinders should have adequate pressure relief and/or release devices (PRD).
• Any pressurized system (piping, manifold, etc.) that can be isolated must have its own PRD that is vented to a safe location. Never rely on a cylinder regulator to protect downstream system components.
• The PRD on a cylinder of liquefied flammable gas shall always be in direct contact (communication) with the vapor space of the cylinder (in use and storage). Never lay a cylinder containing a liquefied flammable gas on its side.
• NEVER block, modify, attempt to repair, or tamper with any PRD.

System Connections

• The Compressed Gas Association (CGA) specifies fittings for each type of gas. There are dozens of styles available for different applications. They are designed to prevent the use of gases with incompatible systems, but some are similar in size and appearance. Always consult the vendor or product literature and verify you are using the correct components for your gas and application.
• Never use an adaptor between a cylinder and pressure-reducing regulator.
• Never replace CGA connections or modify any CG system component unless you are authorized to do so and have verified service compatibility.
• Only qualified contractors or staff should install permanent flammable gas piping.
• If regulators or connectors do not seem to fit correctly, do not force them, they are likely the wrong type!

System Connections

The following pictures are the typical CGA connections that are used for common industrial gases (all of these are for large cylinders, < 3000 psig service, and have 14 threads per inch).

Notice these are deliberately sized different and/or reverse threaded for various gases. They can still be force fit or cross-connected with lapses in logic and good judgment by end users! These fittings should always fit together easily; never force them or use sealant aids such as Teflon tape or pipe dope.

CG System Precautions

• Regulators must always be used with high pressure CG cylinders and systems in order to safely reduce pressure to desired working levels.
• Be certain that only pressure regulators and system components designed for the specific type of gas and application are utilized.
• Gas transfer lines whose entire length cannot be visualized from their source to termination points must be labeled.

CG System Precautions

• Backflow prevention check valves must be used whenever flammables and oxidizers are simultaneously connected in a system. Shutoff valves and system differential pressures shall not be relied upon to prevent backflow.
• Regulators must be disconnected and CG cylinder valves capped whenever the system will be shutdown for extended non-use periods.
• Whenever possible, an inert gas should be used to test performance and check for leaks on new installations or following repairs to CG systems. Never use flames to check for leaks; use soapy solutions or appropriate environmentally rated detectors.

Summary

In this lesson you learned about cylinder inspections and connections. Let's review the key points from this lesson:

All cylinders must have appropriate labels or stamped markings. If these are not present or legible DO NOT USE THE CYLINDER and contact the vendor or EH&S for assistance.

CG cylinders must be in safe working condition, otherwise they are to be removed from service.

Cylinders are not to be used beyond the specified use period. Old and unused cylinders must be returned to the vendor or disposed of by EH&S.

Appropriate fittings, pressure relief devices, and regulators must be used when working with CG cylinders.

Checkpoint

Gauges must be selected that will indicate the maximum system design pressure at no more than what percentage of their face value range.

1. 25%
Incorrect. Gauges must be selected that will indicate the maximum system design pressure at no more than 75% of their face value range, i.e. a 3000 psig cylinder should have a gauge that can indicate at least 4000 psig inlet pressure.
2. 50%
Incorrect. Gauges must be selected that will indicate the maximum system design pressure at no more than 75% of their face value range, i.e. a 3000 psig cylinder should have a gauge that can indicate at least 4000 psig inlet pressure.
3. 75%
Correct. Gauges must be selected that will indicate the maximum system design pressure at no more than 75% of their face value range, i.e. a 3000 psig cylinder should have a gauge that can indicate at least 4000 psig inlet pressure.
4. 100%
Incorrect. Gauges must be selected that will indicate the maximum system design pressure at no more than 75% of their face value range, i.e. a 3000 psig cylinder should have a gauge that can indicate at least 4000 psig inlet pressure.

Safe Operating Practices

• Stand behind cylinders with outlets facing away from you whenever operating cylinder valves.
• Avoid standing directly in front of high pressure gauges, cylinder, system outlets, or other potential system failure points.
• Open and adjust all valves S-L-O-W-L-Y until you hear gas flowing and pressure has equalized.

Safe Operating Practices

• Cylinder valve operations:
• Only open flammable gas valves as far as needed, generally less than 1 ½ turns.
• Non-flammable cylinder valves should be opened fully and closed back about ¼ turn, so that they do not get mistaken as being closed.
• Only use wrenches supplied by the vendor to open cylinder valves, leave these installed on the stem whenever the cylinder is open.
• Never use a wrench, any other tool, or apply excessive force to any valve hand wheel. If the valve seems stuck, contact the vendor.
• Follow laboratory instructions for venting gases. Toxic or flammable gases must be vented to a fume hood and corrosive gas systems should be purged and flushed with an inert gas after use, whenever possible.

Emergency Information

All hazards in each lab are posted by each entrance. This includes all compressed gases.

Know whom to contact from the laboratory in the event of emergency. This information should be updated on the lab posting.

Note: Areas with large amounts of gas or special hazards need to be reported to local responders via EH&S.

Leak Response-General

Fire Response-General

Summary

In this lesson you learned about safe operating practices and emergency response. Let's review the key points from this lesson:

When using a CG cylinder, there are a number of safe practices and precautions that will reduce the likelihood of injury.

To learn about the hazards in each laboratory area, consult the Laboratory Information posting located at the entrance of each laboratory.

In the event of a leak, alert others and evacuate the area as needed. If needed, notify emergency responders by dialing 911 and pulling the fire alarm.

In the event of a fire, notify emergency responders by dialing 911 and pulling the fire alarm.

Checkpoint

Valves should be opened and adjusted slowly until you hear gas flowing and pressure has equalized.

• True
Correct
• False
Incorrect. You should always open and adjust valves S-L-O-W-L-Y until you hear gas flowing and the pressure has equalized.

Checkpoint

If you are using large volumes of asphyxiants, relative to the space size and ventilation rate of the space you are working in, you should have the following:

1. Oxygen level monitors with audible alarms
Correct. Oxygen level monitors can alert you to dangerous conditions. If there are personnel that are hearing impaired other requirements may apply.
2. Mice in a cage near the area where you are working
Incorrect. If you are working under these conditions you will need to have oxygen level monitors with audible alarms.
3. Three coworkers observing you while you work
Incorrect. If you are working under these conditions you will need to have oxygen level monitors with audible alarms.
4. Sprinkler systems installed in the area
Incorrect. If you are working under these conditions you will need to have oxygen level monitors with audible alarms.

References and Resources

• NFPA 55: Storage, Use and Handling of Compressed Gases and Cryogenic Fluids in Portable and Stationary Containers, Cylinders and Tanks
• NFPA 45: Fire Protection for Laboratories Using Chemicals
• NFPA 2: Hydrogen Technologies Code
• Handbook Of Compressed Gases, Compressed Gas Association, Inc.
• 29 CFR 1910: Occupational Safety and Health Standards
• FSU EH&S at 644-6895 or www.safety.fsu.edu

If you have any concerns, or questions, please call Environmental Health and Safety at 644-6895.