Compressed Gas Safety Program

Purpose

Assure that employees handling compressed gases are adequately trained in the inherent hazards of the cylinders and their contents, as well as proper handling, storage, and use according to OSHA requirements.    Compressed gas cylinders can present a variety of hazards due to their pressure and /or contents. This chapter of the safety manual covers requirements which must be followed for the use of all compressed gases. In addition to the standard required work practices for inert gases, hazardous gases may require additional controls and work practices including, but not limited to, the use of gas cabinets, gas monitors, emergency shutoffs, proper equipment design, leak testing procedures, and the use of air supplying respirators for certain highly toxic gases.

It is the policy of [COMPANY] that all compressed gases be handled, stored, received and used in a safe manner consistent with this chapter.  Compressed air shall not be used for cleaning or blowdown activities unless air pressure is regulated to below 30 psig and areas have been isolated from pedestrian traffic.

Numerous potential physical and health hazards are associated with compressed gases, including explosion, poisoning, impact by containers, fire, asphyxiation and exposure related illnesses.

Engineering Controls - each gas application will have it's own engineering controls depending on the types of hazards and application.  Examples of engineering controls are:

• Fume hoods
• Gas Cabinets
• Ventilation systems
• Smoke detectors
• Sprinkler systems
• Flow Restrictors
• Scrubbers
• Leak Monitors
• Gas cylinder storage areas

Administrative Controls - compressed gas program administrative controls include:

• Employee training
• Segregation of gas containers
• Inspections and audits
• Signs
• Assignment and use of PPE
• Identification of authorized employees
• Procedures for receipt, use and storage

Compressed Gas Cylinders

Inspection of compressed gas cylinders. 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 as prescribed in the Hazardous Materials Regulations of the Department of Transportation (49 CFR parts 171-179 and 14 CFR part 103). Where those regulations are not applicable, visual and other inspections shall be conducted in accordance with Compressed Gas Association Pamphlets C-6-1968 and C-8-1962, which is incorporated by reference as specified in Sec. 1910.6.

The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tankcars, or motor vehicle cargo tanks shall be in accordance with Compressed Gas Association Pamphlet P-1-1965

Safety relief devices for compressed gas containers. Compressed gas cylinders, portable tanks, and cargo tanks shall have pressure relief devices installed and maintained in accordance with Compressed Gas Association Pamphlets S-1.1-1963 and 1965 addenda and S-1.2-1963

Prior to use of any compressed gas, a review of the applicable requirement in the Engineering Controls and Work Practices and Procedures section must be conducted.

Class 1 Application - Use of Inert Gases - Gases which are non-flammable and non-toxic, but which may cause asphyxiation due to displacement of oxygen in poorly ventilated spaces

Class 2 Application - Use of Flammable, Low Toxicity - Gases which are flammable (at a concentration in air of 13% by volume or have a flammable range wider than 13% by volume), but act as non-toxic, simple asphyxiants (e.g.hydrogen, methane)

Class 3 Application - Use of Pyrophoric Gases and Liquids - Gases or liquids which spontaneously ignite on contact with air at a temperature of 130 F or below.

Class 4 Application - Use of Corrosive, Toxic, and Highly Toxic Gases - Gases which may cause acute or chronic health effects at relatively low concentrations in air

Class 5 Application - Use of Compressed Gases in Fume Hoods

 

Gas Use Requirements - Engineering Applicability

Gas Use Requirements - Administrative & Procedural Applicability

Notes

X¹ Not required if flow restricting orifice is installed in a cylinder valve. May be required for semiconductor applications

X² Based on the outcome of hazard review

X³ Required in lab and inside gas cabinet for new installations

X⁴ For new installations

X⁵ Typically not required, may be required for semiconductor applications

X⁶ For corrosive gases

X⁷ See Fume Hood Use

X⁸ See Gas Monitoring for details

X⁹ See Hazard Review

X¹⁰ See Cryogenic Liquid

 

Engineering Controls / Design Considerations

This includes a listing of typical engineering controls, referenced in the matrix above. In some cases, Building Codes may require additional controls. Additional controls or deviations from the controls listed below may alsobe appropriate for the application such as those required by the OSHA Process Safety Management Program or EPA's Risk Management Program. The appropriate controls should be identified through the hazard review process.

1. Gas Cabinets - With the exception of cylinders containing a non-toxic, flammable gas, and cylinders used in fume hood applications, hazardous gas cylinders must be housed in gas cylinder cabinets. These cabinets must be equipped with sprinkler protection, and must be constructed and ventilated according to State code requirements. These requirements include, but are not limited to, the need to provide 200 fpm air flow at the cabinet window.

2. Interlocks - In addition to automatic shutoff of gas flow due to loss of power or ventilation (described below), it will often be appropriate for an automatic shutdown of gas flow due to conditions such as high system pressure, high gas delivery pressure, loss of vacuum, loss of cooling, or other conditions identified through the hazard review process.

3. Emergency Off - Where gases are used in gas cabinets, the emergency off buttons should be located at the lab doorway. Activation of this button will cause pneumatic valves to shut, stopping gas flow. Typically, this button should kill electrical power to hazardous lab equipment as well.

4. Equipment Enclosures and Ventilation - Experimental apparatus using hazardous gases should be contained in an enclosed and exhausted tool enclosure. These enclosures must be connected to the exhaust ventilation system. Ventilation rates must be sized to allow for 100 fpm of air flow through the largest open enclosure door. Mass flow controllers carrying hazardous gases must be housed in a separate ventilated enclosure (or in an enclosed compartment of a larger tool enclosure) so that 100 fpm exhaust flow is available at the largest open door to the enclosure. All components should be readily accessible for maintenance.

5. Smoke Detection - All labs using hazardous gases will have a smoke detector which is connected to the building alarm system. In certain cases, it may be necessary to interlock smoke detector activation with the shutdown of hazardous gas flow.

6. Sprinkler Protection - Where hazardous gases are contained in gas cabinets, sprinkler protection should be provided to the interior of the gas cabinet. In some cases, this protection is required by code. Sprinkler protection is recommended in all labs using hazardous materials.

7. Emergency Power - Emergency power is recommended to power exhaust fans connected to hazardous gas enclosures. In certain cases, this protection is required.

8. Pneumatic Shutoff Valves - All corrosive, toxic, flammable, and pyrophoric gases will contain a normally closed pneumatic shutoff valve, rated for at least full cylinder pressure, and located immediately downstream of the cylinder valve. This valve will shut in the event of power failure, remote actuation of an emergency off button (see this topic), or other appropriate conditions such as hazardous gas alarm activation.

9. Scrubbers - When hazardous waste gases are generated, it is often advisable to treat/react these gases prior to exhaust from the building. This may involve the use of bubblers in a fume hood or sophisticated units for larger scale hazardous gas processes. Note that in some cases (e.g minimal volumes of hazardous gases produced) scrubbers may be not necessary or even unadvisable. Where scrubbers are used, they need to be carefully reviewed as part of the hazard review. Maintenance requirements and procedures need to be clearly understood and followed.

10. Vacuum Pumps - Vacuum pumps used for hazardous gases need to be carefully selected. Depending on the gases being pumped, special precautions may be necessary. For processes where pyrophoric gases are used, pumps need to be continuously purged with nitrogen, with loss of nitrogen flow causing the pyrophoric gas supply valves to close. Pumps

This is the FIRST part of this document
The rest of this document can be found in the Members Area
You can join for only 79 cents a day!