Oklahoma State UniversityINTRODUCTION Many industrial and laboratory operations require the use of compressed gases for a variety of different operations.
Oklahoma State UniversityINTRODUCTIONCompressed gases present a unique hazard. Depending on theparticular gas, there is a potential for simultaneous exposure to bothmechanical and chemical hazards. Gases may be: •Flammable or combustible •Explosive •Corrosive •Poisonous •Inert •or a combination of hazards
Oklahoma State UniversityINTRODUCTIONIf the gas is flammable, flash points lower than roomtemperature compounded by high rates of diffusion present adanger of fire or explosion.Additional hazards of reactivity and toxicity of the gas, aswell as asphyxiation, can be caused by highconcentrations of even "harmless" gases such asnitrogen.Since the gases are contained in heavy, highly pressurizedmetal containers, the large amount of potential energyresulting from compression of the gas makes the cylinder apotential rocket or fragmentation bomb.
Oklahoma State UniversityINTRODUCTIONCareful procedures are necessary for handling the variouscompressed gases, the cylinders containing the compressedgases, regulators or valves used to control gas flow, and thepiping used to confine gases during flow.
Oklahoma State UniversityIDENTIFICATIONThe contents of any compressed gas cylinder must be clearlyidentified. Such identification should be stenciled or stampedon the cylinder or a label.
Oklahoma State UniversityColor Coding Yellow: Flammable Brown: Toxic and Poisonous. Blue: Anesthetic and Harmful Green: Oxidizers Grey: Dangerously High Pressure and asphyxiant. Red: Fire Protection
Oklahoma State UniversityIDENTIFICATIONNever rely on the color of the cylinder for identification. Colorcoding is not reliable because cylinder colors may vary withthe supplier. Additionally, labels on caps have little valuebecause caps are interchangeable. Always read the label!
Oklahoma State University IDENTIFICATIONSigns should be conspicuously posted in areas where flammablecompressed gases are stored, identifying the substances andappropriate precautions (e.g., HYDROGEN - FLAMMABLE GAS - NOSMOKING - NO OPEN FLAMES).
Oklahoma State University Cylinder Storage•Gas cylinders must be secured at all times to prevent tipping.Cylinders may be attached to a bench top, individually to the wall, placedin a holding cage, or have a non-tip base attached. Chains or sturdystraps may be used to secure them.•Full and empty cylinders shall be stored in separate locations, in amanner that will allow cylinders with the oldest hydrostatic test date tobe removed first with minimal handling of other cylinders. Cylindersshall be further segregated as necessary by Condition Codeclassification. Full cylinders shall be properly identified with the currentFSC 6830 or 6505 NSNs representing the cylinder and their contents.Empty cylinders shall be properly identified with the correct FSC 8120NSN that represents the empty cylinder.
Oklahoma State UniversityCylinder Storage Cont. The storage facility or storage area shall provide compressed gas cylinders and their contents with protection against physical damage, fire hazards, adverse environmental conditions, and tampering by unauthorized personnel. The storage facility or area shall also provide sufficient isolation of the compressed gases to enable safety and emergency response personnel and equipment to control the situation if a leak were to develop or the cylinders were threatened by a fire in the immediate area. Incompatible gases and incompatible materials shall be physically separated. Compressed gases shall be segregated by their hazard class or division into three primary groups: flammable gas(2.1), nonflammable gas (2.2), and poison gas(2.3)(See para 172.400 of Title 49 CFR).
Oklahoma State UniversityCylinder Storage Outside The cylinders shall be stored above ground on a raised concrete slab or by other means that prevent their contact with the ground. The area should be covered with a fixed noncombustible canopy that will provide protection from inclement weather and the direct rays of the sun. Location of the storage areas shall be crosswind or downwind of any industrial or residential buildings. In the event of a cylinder leak, this will carry the gas away from the congested area; in case of fire in the main building, a crosswind would carry the flame and heat away from the storage area.
Oklahoma State UniversityHANDLING Leaking CylindersIf a leaking cylinder is discovered, the Respiratory ProtectionProgram shall be used when confronting or handling the leakingcylinder. The leaking cylinder shall be removed outdoors to a well-ventilated location or placed under an exhaust ventilating systemsuitable for the product. If the gas is hazardous (e.g., flammable,poisonous, corrosive) an appropriate sign shall be placed at thecylinder warning of the hazardous properties. Under no circumstances should any attempt be made to repair a cylinder or valve.
Oklahoma State UniversityHandling Leaking Cylinders Cont. If emergency assistance or advice concerning the handling of a leaking cylinder or other emergencies involving cylinders is required, the gas supplier should be the first information/assistance source contacted. If the supplier is unknown or not accessible, contact an information source such as the U.S. Coast Guard National Response Center at 800-424-8806 or the Chemical Transportation Emergency Center (CHEMTREC) at 800-424-9300 or 202-483-7616 in CONUS and Canada, Puerto Rico, and the Virgin Islands; from overseas, Alaska, and Hawaii, call 202-483-7616 collect for advice and/or assistance. Under no circumstances should any attempt be made to repair a cylinder or valve.
Oklahoma State UniversityHANDLING & USEStandard cylinder-valve outlet connections have beendevised by the Compressed Gas Association (CGA) toprevent mixing of incompatible gases.The outlet threads used vary in diameter; some areinternal, some are external; some are right-handed,some are left-handed.In general, right-handed threads are used for non-fuel andwater-pumped gases, while left-handed threads are used forfuel and oil-pump gases.
Oklahoma State UniversityHANDLING & USETo minimize undesirable connections, only CGA standardcombinations of valves and fittings should be used incompressed gas installations; the assembly of miscellaneousparts should be avoided.The threads on cylinder valves, regulators and otherfittings should be examined to ensure they correspondand are undamaged.
Oklahoma State UniversityHANDLING & USECylinders should be placed with the valve accessible at alltimes. The main cylinder valve should be closed as soon as itis no longer necessary that it be open (i.e., it should never beleft open when the equipment is unattended or not operating).This is necessary not only for safety when the cylinderis under pressure, but also to prevent the corrosion andcontamination resulting from diffusion of air andmoisture into the cylinder after it has been emptied.
Oklahoma State UniversityHANDLING & USECylinders are equipped with either a hand wheel or stemvalve. For cylinders equipped with a stem valve, the valvespindle key should remain on the stem while the cylinder is inservice.Only wrenches or tools provided by the cylindersupplier should be used to open or close a valve. At notime should pliers be used to open a cylinder valve.Some valves may require washers; this should be checkedbefore the regulator is fitted.
Oklahoma State UniversityHANDLING & USECylinder valves should be opened slowly. Oxygen cylinder valvesshould be opened all the way.Open up the oxygen cylinder valve stem just a crack. Oncethe needle on the high pressure gauge has stopped, open upthe valve all the way. This back-seats the valve.Oxygen cylinders must have the valve opened up all the waybecause of the high pressure in the cylinder. There is a back-seating valve on the oxygen cylinder. This prevents the high-pressure gas from leaking out through the threaded stem.When opening the valve on a cylinder containing an irritating ortoxic gas, the user should position the cylinder with the valvepointing away from them and warn those working nearby.
Oklahoma State UniversityHANDLING & USECylinders containing flammable gases such as hydrogen oracetylene must not be stored in close proximity to openflames, areas where electrical sparks are generated, or whereother sources of ignition may be present.Cylinders containing acetylene shall never be stored ontheir side.
Oklahoma State UniversityHANDLING & USEAn open flame shall never be used to detect leaks offlammable gases. Hydrogen flame is invisible, so "feel" forheat.One common practice is to use a natural bristle broom to"sweep" the air in front of you.All cylinders containing flammablegases should be stored in a well-ventilated area.
Oklahoma State UniversityHANDLING & USEOxygen cylinders, full or empty, shall not be stored in thesame vicinity as flammable gases.The proper storage for oxygen cylinders requires that aminimum of 20 feet be maintained between flammable gascylinders and oxygen cylinders or the storage areas beseparated, at a minimum, by a fire wall five feet high with afire rating of 0.5 hours.Greasy and oily materials shall neverbe stored around oxygen; nor shouldoil or grease be applied to fittings.
Oklahoma State UniversityHANDLING & USERegulators are gas specific andnot necessarily interchangeable!Always make sure that theregulator and valve fittings arecompatible.
Oklahoma State UniversityHANDLING & USEAfter the regulator is attached, thecylinder valve should be openedjust enough to indicate pressureon the regulator gauge (no morethan one full turn) and all theconnections checked with a soapsolution for leaks.Never use oil or grease onthe regulator of a cylindervalve.
Oklahoma State UniversityHANDLING & USEIf there is any question as tothe suitability of a regulatorfor a particular gas, checkwith the EnvironmentalHealth & Safety Departmentor call your vendor foradvice.
Oklahoma State UniversityHANDLING & USEThe following rules should always be followed in regards topiping: Plastic piping shall not be used for any portion of a high pressure system. Do not use cast iron pipe for chlorine. Do not conceal distribution lines where a high concentration of a leaking hazardous gas can build up and cause an accident. Copper piping shall not be used for acetylene.
Oklahoma State UniversityHANDLING & USEThe following rules should always be followed in regards topiping: Distribution lines and their outlets should be clearly labeled as to the type of gas contained. Piping systems should be inspected for leaks on a regular basis. Special attention should be given to fittings as well as possible cracks that may have developed.
Oklahoma State UniversityHANDLING & USEA cylinder should never be emptied to a pressure lower than172 kPa (25 psi/in2) (the residual contents may becomecontaminated if the valve is left open).When work involving a compressed gas is completed, thecylinder must be turned off, and if possible, the lines bled.
Oklahoma State UniversityHANDLING & USEWhen the cylinder needs to be removed or is empty, allvalves shall be closed, the system bled, and the regulatorremoved.The valve cap shall be replaced, the cylinder clearlymarked as "empty," and returned to a storage area forpickup by the supplier.Empty and full cylinders should be stored in separate areas.
Oklahoma State UniversityHANDLING & USEWhere the possibility of flow reversal exists, the cylinderdischarge lines should be equipped with approved checkvalves to prevent inadvertent contamination of cylindersconnected to a closed system."Sucking back" is particularly troublesome where gasesare used as reactants in a closed system.A cylinder in such a system should be shut off and removedfrom the system when the pressure remaining in the cylinderis at least 172 kPa (25 psi/in2).If there is a possibility that the container has beencontaminated, it should be so labeled and returned to thesupplier.
Oklahoma State UniversityHANDLING & USELiquid bulk cylinders may be used in laboratories where ahigh volume of gas is needed.These cylinders usually have a number of valves on thetop of the cylinder.All valves should be clearly marked as to their function.These cylinders will also vent their contents when a presetinternal pressure is reached, therefore, they should bestored or placed in service where there is adequateventilation.
Oklahoma State UniversityHANDLING & USEAlways use safety glasses (preferably with a face shield)when handling and using compressed gases, especiallywhen connecting and disconnecting compressed gasregulators and lines.
Oklahoma State UniversityHANDLING & USEAll compressed gas cylinders, including lecture-sizecylinders, must be returned to the supplier when empty or nolonger in use.
Oklahoma State UniversityTRANSPORTATION OF CYLINDERSThe cylinders that contain compressed gases are primarilyshipping containers and should not be subjected to roughhandling or abuse.Such misuse can seriously weaken the cylinder and renderit unfit for further use or transform it into a rocket havingsufficient thrust to drive it through masonry walls.
Oklahoma State UniversityTRANSPORTATION OF CYLINDERS• Cylinders shall not be rolled, dragged, or slid. Where practical, the user shall use a suitable hand truck, fork truck, roll platform, or similar device with cylinders secured for transportation.• One cylinder at a time may be tilted and rolled to and from a filling or dispensing manifold and, to and from a staging area within the filling plant or using facility.