Compressed Gas Standards

PURPOSE
To establish minimum standards for the safe use of compressed gas cylinders on campus in order to prevent injuries, illnesses and losses.

SCOPE
This standard applies to all campus operations and applies to all compressed gas cylinders.

Performance Expectations:
Receiving and Storage

Arrange a return agreement with suppliers prior to purchase.
Ensure laboratory door placard is current each time gases are received. (Contact EHS for updated labels for door placards).
Cylinder contents must be clearly labeled. Color code does not constitute adequate labeling.
Valve caps shall remain in place except during use.
Always transport cylinders with valve caps securely in place.
Do not accept cylinders which are damaged, not clearly labeled, or do not have a valve protection cap.
Keep oxygen cylinders a minimum of twenty feet from flammable gas cylinders or combustible materials. If this can not be done, separation by a non-combustible barrier at least 5 feet high having a fire-rating of at least one-half hour is required.
Components used for other gases and purposes must never be interchanged.
Cylinders should have current hydrostatic test date (normally less than 5 years old for steel and 3 years old for aluminum) engraved on the cylinder. Cylinders should be returned to the supplier for servicing prior to the expiration date.
All gas cylinders shall be secured in an upright position with upper and lower restraints in racks, holders, or clamping devices. The lower restraint may be exempted only if impractical. When cylinders are grouped together, they should be individually secured and conspicuously labeled on the neck area.
Do not place cylinders near heat, sparks, or flames or where they might become part of an electrical circuit.
Do not store cylinders in exit or egress routes.
Store cylinders in a well ventilated area.

Handling and Use

Wear sturdy shoes (no open-toed, sandals, etc.) when engaging in moving or transporting cylinders.
Use a cylinder cart, secure cylinders with a chain, during transport.
Only Compressed Gas Association (CGA) fittings and components are permitted for use with gas cylinders. Only use regulators approved for the type of gas in the cylinder. Do not use adapters to interchange regulators.
Gas lines must be labeled. Color coding is not allowed.
Contents of the cylinder must be laeled as installed including the hazard class (e.g., poison, flammable, inert,etc). The label facing the wall is not acceptable.
Ensure all connections are tight via leak testing. Cylinders, connections, and hoses should be checked regularly for leaks. Use a flammable gas leak detector (for flammable gases only) or soapy water, or a 50% glycerin-water solution and look for bubbles. At or below freezing temperatures, the glycerin solution should be used instead of soapy water. [Note: When the gas to be used in the procedures is a flammable oxidizing or highly toxic gas, the system should be checked first for leaks with an inert gas (helium or nitrogen) before introducing the hazardous gas.
Leak tests must be witnessed by a third party (e.g.,department Safety Coordinator or designee,EHS representative, safety committee representative, etc.) and logged; e.g., written in research notebook with time and date. The goal of the latter is to have historical information in one retrievable location.
When a special wrench is required to open a cylinder or mainforld valve, the wrench shall be left in place on the valve stem when in use; this precaution is taken so the gas supply can be shut off quickly in case of an emergency; and that nothing shall be placed on top of or near a cylinder that may damage the safety device or interfere with the quick closing of the valve.
After installing an approved regulator, open cylinder valves slowly and away from the direction of people (including yourself). Never force a gas cylinder valve. If the valve cannot be opened by the wheel or small wrench provided, the cylinder should be returned; do not attempt to repair a cylinder valve or regulator yourself.
No attempt shall be made to transfer gases from one cylinder to another, to refill cylinders, or to mix gases in a cylinder in the laboratory.
Keep cylinder valves, regulators, couplings, hoses, and apparatus clean and free of oil and grease.
Compressed gases must not be used to clean your skin or clothing.
Never heat cylinders to raise internal pressure.
Use flashback connectors and reverse-flow check valves to prevent flashback when using oxy-fuel systems.
Regulators must be removed when moving cylinders, when work is completed, and when cylinders are empty.
Do not use copper (>65%) connectors or tubing with acetylene. Acetylene can form explosive compounds with copper, silver, and mercury.
Always leave at least 30 psi minimum pressure in all Empty cylinders.
Label all cylinders when "Empty". All cylinders are to be considered full unless labeled as empty by the user. Empty cylinders must be returned to the supplier and not accumulated.
Do not leave an empty cylinder attached to a pressurized system.

NOTE: EHS discourages the use of lecture bottles if other cylinders are available. Lecture bottles are very difficult to dispose of and they use universal threads and valves (some of which are interchangeable), thus increasing the potential for unintentional mixing. If lecture bottles are used, label all associated equipment with the gas name to prevent unintentional mixing.

Emergency Procedures
If a cylinder leak cannot be stopped by tightening the valve gland or packing nut, follow the appropriate guidelines below, contact University Police dispatch and request EHS' immediate assistance.

Poison Gasses

Immediately leave the room, close the door(s), pull the nearest fire alarm pull station, evacuate the area and call University Police from a safe location.
Meet responding fire department/University responders as they arrive to explain the situation.
Once the situation is stabilized, work with EHS to contact the supplier for disposal.

Flammable or Oxidizing Gasses

Turn off all sources of ignition in the room before leaving if shut offs are accessible.
Leave the room, close door(s), pull the nearest fire alarm pull station, evacuate the area and call University Police from a safe location.
Meet responding fire department/University responders as they arrive to explain the situation.
Once the situation is stabilized, work with EHS to contact the supplier for disposal.

Inert Gasses

Place the cylinder in a well-ventilated location, preferably an outdoor cylinder storage area and contact the vendor for removal.

Consequences
"The University views on the job injury and illness, property damage and loss, and environmental release as serious and preventable." (P&P 2-73)

Misconduct which contributes to on the job injury or illness, property damage or loss, or environmental release (hazardous release to air, ground, storm, or sewer)is serious and potential grounds for termination of support, including employment under appropriate University procedures and as defined for this instruction includes:

Flagrant and repeated failure to adhere to or to receive approvals required for work under regulations of Federal, State, local, or University agencies.
Dishonesty in reporting, ranging from fabricating leak testing information to omission of facts during an incident inquiry or investigation.
Covering up or otherwise failing to report health and safety hazards created by others that one has observed.
Taking punitive action against an individual for reporting safety and health hazards.

Appendix A - Hydrogen Gas & Mixtures

Characteristics
Pure hydrogen is a colorless, odorless, tasteless, highly flammable gas exhibiting unique characteristics. It is also the lightest-weight gas. The primary hazards are fire and explosion. Hydrogen is nontoxic but may induce suffocation by diluting the concentration of oxygen in air below levels necessary to support life. Special materials of construction are not usually required since hydrogen is noncorrosive; however, embrittlement occurs in some metals at elevated temperatures and pressures.

Hydrogen forms explosive mixtures with air from 4% to 75% by volume. These explosive mixtures of hydrogen with air (or oxygen) can be ignited by a number of finely divided metals (such as common hydrogenation catalysts). Hydrogen can also spontaneously ignite from entering the air at high pressure.

A property peculiar to hydrogen occurs upon rapid release. Expansion of hydrogen released rapidly from a compressed gas cylinder will cause an increase in temperature due to its negative Joule-Thompson coefficient.

Some hydrogen mixtures may substantially increase the hazard potential. For example, mixtures with hydrogen sulfide are highly toxic.

System Design and Installation
The design and installation of hydrogen systems shall be documented in one of the following ways:

A review by the College Safety Committee or designee, and/or EHS is required for all vessels and piping systems prior to usage, except those that are American Society of Mechanical Engineers (ASME), American National Standards Institute (ANSI), and Department of Transportation (DOT) certified and have not been modified. A similar review is required for hydrogen piping systems with pressure greater than 60.0 psig. Additional review is required when the system is moved or altered in any way.
A visible label, tag, or other record indicating that the system has been approved for use by the College Safety Committee or designee, and/or EHS. Such label will list any precautions, operating provisions and limitations, or requirements.

Hydrogen gas systems should be designed for ease of operation and maintenance (e.g., changing cylinders).
Stationary vessels and piping should be designed to the ASME code and the ANSI Pressure Piping code for the pressures and temperatures involved.
All storage containers, piping, valves, regulating equipment, and other accessories must be readily accessible and protected against physical damage and tampering.
The piping, tubing, and fittings in all hydrogen systems - as well as valves, gauges, regulators, and other accessories - shll be suitable for hydrogen service and for the pressures and temperatures involved.
Hydrogen regulators must be factory marked as CGA 350 and unmodified on the high-pressure side. Copper and stainless steel tubing must be factory pre-cleaned (ASTM 280) or certified as instrument grade. Tubing quality and source must be documented in the same manner as leak testing.
Mobile hydrogen supply units shall be electrically bonded to the system before discharging hydrogen.
Many metals undergo embrittlement upon exposure to hydrogen. Thus, it is important to select suitable materials to safeguard against this condition. Stainless steel is preferred for all hydrogen lines, and required for all lines greater than 60.0 psig. Welded joints shall be used on systems where the pressure is greater than 60.0 psig at the low side of the regulator. Copper lines and swedgelock fittings may be used on systems of 60.0 psig or less provided that the lines are less than 20 feet, completely visible, and confined to one bench or work area. Cast iron pipe and fittings are not suitable and shall not be used. The use of plastic tubing for any part of a hydrogen system is prohibited. Copper lines that penetrate walls or ceilings are also prohibited.
Flammable Mixtures Confined hydrogen/air mixtures can detonate instead of burn. Hence, it is imperative to prevent the formation of flammable hydrogen/air mixtures in the system. Evacuate hydrogen systems or render them inert, both before and after use. Consider methods for inert gas purging of systems that are cycled frequently. Providing simple purge connections may be sufficient for systems that are not normally exposed to air.

When air or other oxidizing gases connect to a hydrogen system, install a check valve on the oxidizer supply and flash arresters on the hydrogen supply. Refer to the manufacturer's catalog for both check valves and flash arresters to verify that they have been designed for hydrogen use.
Ventilation Hydrogen shall be used only in well-ventilated areas. The amount of ventilation required will vary in each case depending on the total supply of hydrogen, the rate of use or generation, and the venting arrangement from the process or hydrogen system. As a general rule, most laboratories with fume hoods have sufficient ventilation to permit the use of small amounts of hydrogen without major modifications.

NOTE: Venting out of a window presents a variety of potential problems due to the re-entrainment of exhaust gases. Venting out of a window is allowed only with the approval of the College Safety Committee or designee, and/or Environmental Health and Safety (EHS).
Ignition Sources. The system designer shall ensure that hydrogen is not exposed, under any condition, to unintended ignition sources such as open flames, electrical equipment, or heating devices. Enclosures shall provide adequate ventilation, and all electronic and electrical equipment shall be designed and rated for hydrogen use. This may require use of NEC Class I equipment and wiring. Electrically bond and ground all noncurrent?carrying metal parts to remove static charges.

Additionally, purged enclosures are required for systems or special applications that have ignition sources and the potential capability to generate an explosion.

Handling and Use

In situations where there is the possibility of an explosion, the use of special protective apparel (e.g. face shields, gloves, and laboratory coats) and protective devices such as explosion shields, barriers, enclosed barricades, or even an isolated room with a blowout roof or window should be considered.
A suspected flame should be approached with extreme caution, such as by the use of a straw broom. Hydrogen is a highly flammable gas that burns with an almost invisible flame and low thermal radiation.
Training in the nature and use of the operation by all individuals who may work with or control the system must be provided initially and if research procedures change.
Prior to introduction of gas into a reaction vessel, purge the equipment by evacuation or with an inert gas. The flush cycle should be repeated three times to reduce residual oxygen to about 1%.
Periodic leak testing of systems must be conducted and documented.

Special circumstances requiring additional work practice procedures, external review, operational checklists, and emergency shutdown procedures:

Any operation in an enclosed space or area capable of creating hydrogen air concentration greater than four percent.
Hydrogen systems with line pressures greater than 60.0 psig.
Hydrogen systems containing more than 3,000 ft3 (STP) of hydrogen gas.
Systems using liquid hydrogen. (Liquid hydrogen is not covered by this document)
Any other condition deemed as significant by the Principal Investigator, College Safety Committee or designee, and/or Environmental Health and Safety (EHS).

Supply Location and Cylinder Storage

The line pressure in the distribution system should not exceed 60.0 psig. Gas systems with greater pressure are subject to additional National Fire Protection Association (NFPA) requirements.
Store extra hydrogen cylinders in well-ventilated locations, preferably outdoors, away from flammable and combustible materials. Not more than 3,000 total cubic feet (STP) of hydrogen may be stored in any single area inside of a building. A 2200 lb cylinder equates to ~197 ft3 of hydrogen at STP.
Hydrogen cylinders shall be stored secured and capped and at least 20 ft from all oxidizing gases or be separated by a noncombustible, fire-resistant barrier with at least a one hour rating.
Permanently installed containers shall have substantial noncombustible supports on firm noncombustible foundations.
Post signs at all hydrogen storage locations that read:
"DANGER--HYDROGEN--FLAMMABLE GAS--NO SMOKING--NO OPEN FLAMES."

Hydrogen Detectors

Fixed hydrogen detection devices and alarms are required for all systems involving large quantities of hydrogen where long-term leaks could create an explosive mixture. For instance, alarms are typically required in facilities serviced by tube trailer banks, but are not necessary in systems with fewer than four full-sized cylinders because a leak sufficient to create an explosion would probably exhaust the hydrogen supply before the Fire Department could respond.
EHS should be consulted in cases where a hydrogen detector is needed, prior to the time of installation.

12/08/03