Compressed Gas Cylinder Safety Guidelines

Transcription

1 Compressed Gas Cylinder Safety Guidelines I. Introduction These guidelines contain information on the proper storage, handling, use and disposal of compressed and liquefied gas cylinders. Information is first presented from the general, all-hazards, perspective, and from the specific hazard classes. II. Purpose and Scope Compressed and liquefied gases are routinely used in many operations at the University. The intent of this guideline is to provide information on their safe usage, and thereby aid employee protection from potential health and physical hazards. Only trained and qualified personnel should be allowed to use compressed or liquefied gases. Training should include the hazards of the materials, the technical nature of apparatus, applicable safety precautions, personal protective equipment (PPE) and emergency response procedures. Safety data sheets, manufacturer guidance such as SafetyGrams TM 1, and standard operating procedures must be made accessible to gas users. Additional information and training opportunities are available through Environmental Health and Safety, and through trade associations such as the Compressed Gas Association. 2 III. Cylinders: Storage Requirements Shall not be stored in exits or egress routes. Shall be stored in well-ventilated areas. Shall not be stored in damp areas, near salt or corrosive chemicals, fumes, heat or where exposed to weather. Shall be stored in an upright position (non-liquefied lecture bottles may be stored horizontally in specifically designed racks). Shall be secured with a chain or belt at 2/3 of cylinder height, and in earthquake hazard zones a second chain or belt should secure at 1/3 of cylinder height. Laboratory cylinders (e.g. lecture bottles) less that 18 tall may be secured in stands, clamps, or wall brackets. 1 (accessed March 3, 2013). 2 (accessed March 3, 2013). Rev. Feb 2013 Page 1 of 12

2 Shall have regulator removed, and be securely capped, when in storage. Note: some cylinders may not accept caps. Shall be kept at least 20 feet away from other incompatible gases. A 5 foot noncombustible wall (minimum 1 hour fire rating) may be used to segregate flammable and oxidizing gases when storage in close proximity is necessary. Shall be stored such that cylinders are used in the order they are received. Shall be stored such that like hazard classes are together. Inert gases may be stored with any of the hazard classes. Shall not be stored longer than one year without use. Shall be stored such that full cylinders are distinguished separately from empty cylinders. Storage Quantity and Volume: Maximum allowed usage and storage of flammable, oxidizing, and toxic gases are set for laboratory work areas by Oregon Fire Code 3, and consensus standards such as NFPA Allowable quantities change with elevation above or below ground level, with hazard class, and with engineered protective measures; a summary is provided within Table 1. Table 1 Maximum Gas-phase Volume Quantity (ft 3 ) of Hazardous Gases in Laboratories by Building Level Hazard Highly Toxic 5 Ventilated Enclosure No Ventilated Enclosure Sprinkled Non-Sprinkled Sprinkled Non-Sprinkled None Toxic Flammable Oxidizing IV. Cylinder Handling Requirements Cylinders shall only be handled by trained persons. Training must include the contents of this guide, relevant information within the UO Chemical Hygiene Plan, and specific information related to the cylinder contents. Closed-toed, sturdy shoes are required when moving cylinders. Cylinders shall be transported on a cylinder cart with cylinder restraints and caps in place. 3 (accessed March 3, 2013) 4 (accessed March 3, 2013) 5 NFPA health hazard of 4 6 NFPA health hazard of 3 Rev. Feb 2013 Page 2 of 12

3 Only the gas supplier should fill a high-pressure cylinder. Damaged or leaking cylinders should be immediately reported to EHS. Such cylinders shall not be shipped to the supplier without supplier s prior written approval. Magnets shall not be used to lift cylinders. Cylinders shall only be painted by the manufacturer. V. Compressed and Liquefied Gas Use Best Practices General Requirements Soap-bubble test cylinders for gas leaks upon receipt. Do not accept leaking cylinders. Regulator pressure control valves shall be closed prior to attachment to a cylinder. Close valves on cylinders when not in use. Remove pressure on regulators not in use by opening downstream valves after the regulator is closed. Shut-off valves must not be installed between equipment and any necessary pressure relief device. Pressure relief valves should be installed in downstream lines to prevent pressure buildup should regulator valve not fully seat, and a tank valve be left on. Relief valves should be vented to prevent buildup of toxic or flammable gas. Flames or concentrated heat sources should never contact a gas cylinder. A cylinder must never be part of any electrical circuit. Do not partially open a cylinder to clear dust or debri from the cylinder inlet. Pressurize regulators slowly, and with all valve outlets and regulator faces pointed away from personnel, when opening a cylinder valve. Cylinders that require a wrench to operate the valve shall have the wrench left in place during use of the cylinder. Cylinder valves shall only be opened to the point where gas flows into the system at the necessary pressure (typically a half or full turn). This allows for quick shutoff in the event of regulator failure or an emergency. Do not open corroded valves. They may be impossible to reseal. Piping, regulators, and connected apparatus must have tight seals, and be regularly tested for leaks. Release all pressure from a system prior to tightening, loosening, or repairing connections. Do Not Use TeflonTM tape on CGA fittings where the seal is made by metal-to-metal contact. Tape may in fact spread threads and weaken seals. Do not use adaptors between tanks and regulators. Only use regulators designed for the gas being used. Rev. Feb 2013 Page 3 of 12

4 Labeling Requirements Vendor labels must be maintained in good condition, and remain visible to operators. Empty cylinders must be labeled Empty, MT via collar or other visible mechanism. Labeling should include contents of the cylinder and the hazard present. CGA Pamphlet C-7: Precautionary Labeling and Marking of Compressed Gas Cylinders is a primary resource. Manifolds, Valves and Regulators Manifolds and regulators must be designed (temperature, pressure, flow rate, and material properties) according to the materials they will carry. Pressure gauges must be appropriate for the pressure of the cylinder. Threads, configurations, and valve outlets are designed to be different for each class of gas to prevent mixing of incompatibles (lecture bottle apparatus are an exception). Do not engineer a system that defeats this important safety design feature. Lecture bottles have universal threads and special care with labeling and flushing must be taken to prevent mixing of incompatibles. CGA Pamphlet V-1: Standard for Compressed Cylinder Valves, lists appropriate valves for each gas. This information can also be acquired from gas manufacturers and distributors. Valves and regulators should be inspected regularly, and be returned for professional evaluation according to maintenance schedules recommended by suppliers and manufacturers (every 5 years of service is advisable). Upon every use, a visual inspection should look for damage, corrosion, or other defects. Valves that appear in good repair always have the potential to fail. Therefore, highly toxic gases must always be used and stored within ventilated enclosures. Maintenance logs should be kept for all components of a gas delivery system. Maintenance on valves and regulators should only be performed by qualified staff such as technical specialists, manufacturers, and distributors. VI. Hazard-Class Specific Information Corrosive Gases (e.g. chlorine, hydrogen chloride, hydrogen sulfide, fluorine) Metals become brittle upon long exposure. Check frequently for cracks and leaks. Check with gas supplier for the recommended equipment. Steel and bronze are destroyed by corrosion. Remove regulators after use and flush with dry air or nitrogen. Cryogens Most cryogens vaporize at gas:liquid ratios of 600:1; some much higher. Be alert for potential oxygen-deficient conditions in any large release of cryogen. Rev. Feb 2013 Page 4 of 12

5 Use eye and skin protection whenever transferring cryogens. All cryogen containers and delivery systems must be equipped with pressures relief devices to prevent excessive pressure buildup. Never defeat pressure relief valves, discs, or relief settings. Only thaw frostbite in lukewarm water (<105 F). Only use equipment specifically designed for service with cryogens. Ice buildup can cause container, or delivery apparatus, damage. Prevent buildup. Do not use water to thaw liquid helium apparatus. Flammable Gases Only protected fuel gases may be used near ignition sources. Ignition sources include open flames, sparks, heat sources, oxidizers, and ungrounded electrical equipment. Portable fire extinguishers must be immediately available. Leak testing must regularly be performed with compatible leak detection solution. Manifold systems must be designed and constructed by personnel thoroughly familiar with code requirements of piping flammable gases. Consult with EHS and your gas supplier. Fuel and Oxidizing Gases Fuel gases use a combination of flammable and oxidizing gas (e.g. welding/cutting torches). Use must comply with 29CFR Oyxgen-Fuel Gas Welding and Cutting, 29CFR Acetylene, and 29CFR Hydrogen. Additional guidance and referenced safety requirements are found in CGA Pamphlets G-1 and SB-8, and the National Fire Protection Association (NFPA) Standard 51. Oxidizing gases are non-flammable gases that support and vigorously accelerate combustion. Never use oxidizing gases with apparatus that include ignition sources and fuel (e.g. oil). Gauges and regulators for oxygen shall have the warning Oxygen Use No Oil. Toxic and Highly Toxic Gases All gases with a NFPA rating of 3 (Toxic) or 4 (Highly Toxic) must be stored and used in accordance with the provisions of Table 1. All Highly Toxic gases must be stored in a mechanically ventilated gas cabinet, fume hood, or other mechanically ventilated enclosure designed to safely exhaust gases. o Small quantities such as lecture cylinders, and dilute concentrations of toxic gases, may be within general storage in a laboratory having properly functioning general exhaust. Audible, continuous monitoring alarms shall be used with mechanically ventilated enclosures storing Highly Toxic gases. Standard Operating Procedures (SOPs) shall be developed when using Highly Toxic or Corrosive gases. These SOPs shall include emergency response protocols, and shall be required training for all involved employees. Rev. Feb 2013 Page 5 of 12

6 VII. Gas Cylinder Disposal When possible, only purchase cylinders from vendors that agree to take back and refill the empty cylinder. o Refillable cylinders should always be left with a slight positive pressure (7 psig) to prevent contaminants from entering the cylinder. A cylinder is considered empty, and may be disposed as nonhazardous waste, when the container pressure is at atmospheric. Cylinders that do not have a label may often be identifiable through stamp marks on the cylinder. Contact the vendor, Science Stores, or EHS for assistance. Non-empty hazardous gas cylinders must be disposed through EHS. Disposal fees for damaged cylinders and cylinders containing unknown gases are extreme, and may be charged back to departments. VIII. Handling Compressed Gas Cylinder Leaks and Emergencies Preplanning is a critical component of being prepared for any emergency involving compressed gas. The magnitude and cost of damage to personnel and property is directly related to the scope and quality of a laboratory s emergency plan and procedures. Users of compressed gases must develop SOPs and response plans. SOPs shall include possible accident scenarios, appropriate response, and address the following issues: Nature of the operation (e.g. experimental design, injury potential). Location of any potential release or spill (e.g. hood, laboratory, corridor, outdoors). Quantity of materials potentially released, and containment strategies (e.g. tank size, manifold system, phase expansion). Chemical and physical properties of the compressed gas (e.g. vapor pressure, reactivity). Hazardous properties of the compressed gas (e.g. toxic, corrosive, flammable). Availability and locations of emergency supplies and equipment. Response plan that identifies evacuation routes and emergency procedures, and where posted within the laboratory. Minor Leaks (localized & very low flow) Verify location using a leak detection solution. Repair may simply be tightening a connection. Flammable, inert or oxidizing gas cylinder should be moved to a well-ventilated location without ignition sources or combustible materials, signed with respect to hazard, and then brought to the attention of EHS and technical staff. Corrosive and toxic gas cylinders should be moved to an isolated, well-ventilated, location; have the leak directed into an exhaust capture device, signed with respect to hazard, and then brought to the attention of EHS and technical staff. Rev. Feb 2013 Page 6 of 12

7 If necessary to move a cylinder with a minor leak through a corridor, or other general access areas, bag or shroud the cylinder in a manner that will confine the leaking gas according to its physical properties (e.g. vapor density, reactivity). Major Leaks (not localized, or high flow) If immediately available PPE is not sufficient to ensure worker safety, activate Emergency Response Procedures. o Evacuate the laboratory and close doors. o Call 911 and report the incident. o Activate building fire alarms to evacuate the building. o Alert University Response Personnel and remain on the scene to provide details of the incident to Fire, Police, and other responding personnel (e.g. EHS, Campus Operations). Accidents involving Injury Do Not Enter an unknown atmosphere with an unresponsive victim. Call 911 for medical emergencies. Assistance with first aid may include: o Thorough rinsing under a safety shower. o Removal of contaminated clothing, and assistance with replacement coverings. o Rinsing eyes with an eyewash. o Assistance with first aid kit supplies. o Administering CPR. If injury victim is not ambulatory, move only if necessary to prevent exposure to additional harm. Rev. Feb 2013 Page 7 of 12

8 APPENDIX A REFERENCES Compressed Gas Association, Inc., Pamphlet C-6: Standards for Visual Inspection of Compressed Gas Cylinders, Compressed Gas Association, Inc., Pamphlet P-1: Safe Handling of Compressed Gases, Compressed Gas Association, Inc., Pamphlet C-7: Precautionary Labeling and Marking of Compressed Gas Cylinders, Compressed Gas Association, Inc., Pamphlet S-1.1: Pressure Relief Device Standards Part 1 Cylinders for Compressed Gases, Compressed Gas Association, Inc., Pamphlet V-9: Standard for Compressed Gas Cylinder Valves, Compressed Gas Association, Inc., Pamphlet G-1: Acetylene, Compressed Gas Association, Inc., Pamphlet G-3: Sulfur Dioxide, Compressed Gas Association, Inc., Pamphlet G-4: Oxygen, Compressed Gas Association, Inc., Pamphlet G-5: Hydrogen, Compressed Gas Association, Inc., Pamphlet G-7: Compressed Air for Human Respiration, Compressed Gas Association, Inc., Pamphlet G-8.1: Standard for Nitrous Oxide Systems at Consumer Sites, Compressed Gas Association, Inc., Pamphlet G-12: Hydrogen Sulfide, Compressed Gas Association, Inc., Pamphlet P-9: The Inert Gasses: Argon, Nitrogen and Helium, Compressed Gas Association, Inc., Pamphlet P-12: Safe Handling of Cryogenic Liquids, Compressed Gas Association, Inc., Pamphlet P-20T: Tentative Standard for the Classification of Toxic Gas Mixtures, Compressed Gas Association, Inc., Pamphlet SB-8: Use of Oxy-fuel Gas Welding and Cutting Apparatus, National Research Council, Prudent Practices in the Laboratory (Washington, D.C.: The National Academies Press, 2011) A.K. Furr, Ed., CRC Handbook of Laboratory Safety, 4 th ed. (Boca Raton, FL: CRC Press, 1995) Rev. Feb 2013 Page 8 of 12

9 Occupational Safety and Health Administration (OSHA) General Industry Standards: 29 CFR , 29 CFR , 29 CFR NFPA 45: Fire Protection for Laboratories Using Chemicals, National Fire Protection Association, NFPA 51: Standard for the Design and Installation of Oxygen-Fuel Gas Systems for Welding, Cutting and Allied Processes, NFPA 55: Storage, Use and Handling of Compressed and Liquefied Gases in Portable Cylinders, National Fire Protection Association, Oregon Life/Safety Building Codes, (accessed March 7, 2013). Rev. Feb 2013 Page 9 of 12

10 APPENDIX B REGULATOR VISUAL INSPECTION CHECKLIST Labeling : Pressure Range Acceptable Unacceptable Gas Contamination/Corrosion. Correct pressure range for application. Inlet Condition Outlet Condition Controls move freely. High pressure gauge undamaged. Low pressure gauge undamaged. High pressure gauge steady. Low pressure gauge steady. High pressure gauge zeros. Low pressure gauge zeros. Outlet pressure creep. Internal gas leak. External connection leak. Overall condition (pass/fail) Inspector Inspection date Rev. Feb 2013 Page 10 of 12

11 APPENDIX C EXAMPLE REGULATOR LABELING SCHEME Rev. Feb 2013 Page 11 of 12

12 APPENDIX D EXAMPLE REGULATOR MAINTENANCE LOG ID Inspection In-Service Regulator Use Regulator Details Maintenance History Number Due Date Date Location Use Make Stage(s) Max In/Out PSI Gas Type CGA Fitting Model # Serial # Relief UL Listed Other Information Date Details 111 1/1/2015 1/1/2010 Klamath 365 HPLC Scott two 3000/200 Helium External High Purity; SS diaphram 3/1/2013 PO# 123, Scott Specialty Gases Rev. Feb 2013 Page 12 of 12