EARLBECK GASES & TECHNOLOGIES

Transcription

1 EARLBECK GASES & TECHNOLOGIES Pulaski Highway Technical Support Hotline (410) C O M P R E S S E D G A S I D E N T I F I C AT I O N, S P E C I F I C S, C O N TA I N E R S A N D H A N D L I N G H A R D WA R E

2 P L E A S E N O T E : This program is intended only as a basic guide to understanding the applicable subject matter. For detailed rules and regulations, contact the Compressed Gas Association for the applicable information to your specific application as well as your local, state and facility authorities.

3 COMMON TERMS AND DEFINITIONS CGA (Compressed Gas Association)- CGA develops and publishes the broadest distribution of technical information, standards, and recommendations for safe and environmentally responsible practices in the manufacture, storage, transportation, distribution, and use of industrial gases. DOT (Department of Transportation) - the United States federal department that institutes and coordinates national transportation programs NFPA (National Fire Protection Agency)- The world's leading advocate of fire prevention and an authoritative source on public safety, NFPA develops, publishes, and disseminates more than 300 consensus codes and standards intended to minimize the possibility and effects of fire and other risks. Gas Valve- A valve to control the deliverance of gas

4 GAS CLASSIFICATION Gases are categorized according to their basic chemical properties and placed into hazard classes. A gas can be inert, such as argon or nitrogen, in most general applications. They can be corrosive such as chlorine, an oxidizer such as oxygen or nitrous oxide, a fuel such as acetylene or propane, a poison such as cyanide, or a combination where a gas may fit into several categories. Each gas has its own hazards whether it be the pressure at which the gas is stored, its ability to displace oxygen from an enclosed area, or its ability to ignite and burn or explode. Depending on the particular gas, there is a potential for simultaneous exposure to both mechanical and chemical hazards. Gases may be: Inert Corrosive Oxidizer Fuel Toxic A Combination of the above

5 GENERAL GAS PURITY STANDARDS Industrial gases: are a general group of gases used within industry for a variety of purposes. These gases are normally separated in an atmospheric cracking process and packaged with minimal processing. Some applications for these gases are shielding welds during the welding process, metal cutting, purging, and window insulation. Specialty gases: represent a group of gases that are tested to higher degrees than industrial gases and are normally used in research, medical and special applications. These gases are held to a higher standard with less impurities and contamination. These additional requirements make these gases have a higher cost due to the additional processing. Some applications for these gases are research, food blanketing, and testing. Cryogenics gases: are gases stored in their liquid state at very low temperatures that can be used either in this liquid state or in their gaseous state. These gases are not highly compressed and have a limited time period that they will remain in the storage container before evaporating. These gases are intended for high volume use situations, as well as for cooling applications where they are used in their liquid states.

6 CYLINDER INFORMATION Cylinders are manufactured according to DOT regulations, which specify the material of construction, method of manufacture, testing, and what products they are permitted to be filled with, as well as other details. A cylinder is a hollow tube with a closed concave base that permits it to stand upright. The opposite end is tapered to a small opening, threaded to accommodate the installation of a valve. A threaded neck ring is attached to the tapered end to allow a protective cylinder cap to be installed. Cylinders may be used individually or in groups. When used in groups, the cylinders should be piped together, for stationary storage or to form portable banks. Earlbeck Cylinder Fill Plant

7 CYLINDER MARKINGS 1. Cylinder Specification DOT Department of Transportation, which is the regulatory body that governs the use of cylinders. Specification of the cylinder type of material of construction (e.g., 3AA). Service or working pressure in pounds per square inch (e.g., 2,265 psi). 2. Cylinder Serial Number 3. Date of Manufacture - This date (month-year) also indicates the original hydrostatic test. 4. Neck Ring Identification - Displays the name of the current owner of the cylinder. 5. Retest Markings The format for a retest marking is: Month-Facility-Year-Plus Rating-Star Stamp The + Symbol (Plus Rating) indicates the cylinder qualifies for 10% overfill. The Symbol (Star Stamp) indicates that the cylinder meets the requirements for 10-year retest. 6. Cylinder Manufacturer s Inspection Marking 7. Cylinder Tare (Empty) Weight 8. Gas Cylinder Label This sticker indicates the type of gas in a cylinder, as well as its properties and hazards.

8 CYLINDER DIFFERENTIATION Cylinders can be differentiated by 1. the valve installed (which is gas specific and stamped with the CGA number) 2. and the label on the cylinder. (Label must be present or cylinder must not be used) No compressed gas cylinder should be accepted for use that does not legibly identify its contents by name. If the labeling on a cylinder becomes unclear or an attached tag is defaced to the point the contents cannot be identified, the cylinder should be marked "contents unknown" and returned directly to the manufacturer. Do not use cylinder color in order to determine cylinder content. Gas cylinders are often color coded but because the codes are not standardized between different vendors, cylinder color cannot be safely used for gas content identification. Even though medical gas cylinders do use industry standard color coding, the paint color may change over time and with weathering, so it is only safe to identify a cylinder s contents by it s label. Do not use cylinder if cylinder label is missing!

9 CYLINDER PRESSURE Each specific application has a cylinder pressure required for your process. Example - Nitrogen comes in a variety of pressures for varying applications. A standard pressure of 2200psi might be adequate for most applications such as purging or processing while your requirements to fill actuators or other equipment may require pressures of 3500psi or 6000psi. Know your equipment. Also for safety reasons know what pressure your gas handling equipment is designed for. Changing equipment designed for 2200psi on a 6000psi cylinder would be disastrous. Do not use the term high pressure when requesting gas, be specific and always state the pressure required.

10 CYLINDER STORAGE Cylinders should be stored upright in a well ventilated, dry, cool, secure area that is protected from the weather and preferably fireresistant. Cylinders that contain fuel gases whether full or empty must be stored away from oxidizer cylinders at a minimum of 20 feet No part of a cylinder should ever be allowed to exceed 125 F (52 C) and areas should be free of combustible materials. Never deliberately over-heat a cylinder to increase the pressure or discharge rate. Cylinders should be stored away from heavily traveled areas and emergency exits. Avoid areas where salt and other corrosive materials are present. The valve outlet seal and valve protective cap should be left in place until the cylinder has been secured against a wall or bench, or placed in a cylinder stand and is ready for use.

11 CYLINDER STORAGE CONTINUED Cylinders may be attached to a bench top, individually to the wall, placed in a holding cage, or have a non-tip base attached. Chains or sturdy straps may be used to secure them. Cylinders containing flammable gases such as hydrogen or acetylene must not be stored in close proximity to open flames, areas where electrical sparks are generated, or where other sources of ignition may be present. When the cylinder needs to be removed or is empty, all valves shall be closed, the system bled, and the regulator removed. When returning empty cylinders, ensure the valve is closed and that some positive pressure remains in the cylinder. The valve cap shall be replaced, the cylinder clearly marked as "empty by use of a hanging tag, and returned to a storage area for pickup by the supplier. Do not store full and empty containers together.

12 HANDLING If difficulty is experienced operating the container valve or using the container connections, discontinue use and contact the gas supplier. Use only the proper connections on the container. Do not use adapters. Do not under any condition use any type of lubrication, oil or chemical on the threads of the cylinder or the regulator. This may cause an explosion that could cause possible damage to the regulator or cylinder but most importantly, it could injure or cause fatality to those standing nearby. When work involving a compressed gas is completed, the cylinder must be turned off, and if possible, the lines bled. Never drop, drag, roll or slide cylinders. Use a specifically designed hand-truck for cylinder movement. Never attempt to lift a cylinder by its cap.

13 HANDLING Wrenches should never be used to open or close a valve equipped with a handwheel. If the valve is faulty, contact the gas supplier. Never insert an object (e.g. screw driver, pry bar, etc.) into the opening of the cylinder cap. Doing so may damage or inadvertently open the valve. Use only a specially designed strap-wrench to remove over- tightened or rusted caps Leak check all joints and fittings after changing a cylinder. Use the appropriate leak (oxygen compatible) check solution. Soapy water is not an acceptable leak check solution since soap can contain petroleum products. An open flame shall never be used to detect leaks of flammable gases. Hydrogen flame is invisible, so "feel" for heat. If a leaking cylinder is discovered, move it to a safe place (if it is safe to do so) and inform the Environmental Health & Safety Department. You should also call the vendor as soon as possible. Never tamper with the safety devices on valves or cylinders. A cylinder should never be emptied to a pressure lower than 25 psi (172kPA). The residual contents may become contaminated if the valve is left open.

14 HANDLING Cylinders should be placed with the valve accessible at all times. The main cylinder valve should be closed as soon as it is no longer necessary that it be open (i.e., it should never be left open when the equipment is unattended or not operating). This is necessary not only for safety when the cylinder is under pressure, but also to prevent the corrosion and contamination resulting from diffusion of air and moisture into the cylinder after it has been emptied. Use piping and equipment designed to with- stand the maximum pressures encountered. Use a pressure reducing regulator or separate control valve along with properly designed pressure relief devices to safety discharge gas to working systems. Use a check valve to prevent reverse gas flow into the containers. It is recommended that all vents be piped to the exterior of the building and are in accordance with local regulations. Refilling or shipping a compressed gas cylinder without consent of the owner is a violation of federal law. Under no circumstances should any attempt be made to repair a cylinder or valve. For all detailed specifications of cylinder storage and handling, please contact the Compressed Gas Association.

15 GAS USAGE Careful procedures are necessary for handling the various compressed gases, the cylinders containing the compressed gases, regulators or valves used to control gas flow, and the piping used to confine gases during flow. Open up the oxygen cylinder valve stem just a crack. Once the needle on the high pressure gauge has stopped, open up the valve all the way. This back-seats the valve. Always open a compressed gas cylinder valve slowly to avoid rapid system pressurization. All high pressure cylinder (above 300psi) valves should be opened all the way because 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 or toxic gas, the user should position the cylinder with the valve pointing away from them and warn those working nearby.

16 PERSONAL PROTECTIVE EQUIPMENT (PPE) Personnel must be thoroughly familiar with properties and safety considerations before being allowed to handle gases and/or its associated equipment. Safety glasses, safety shoes, and leather work gloves are recommended to handle cylinders. In emergency situations, wear a selfcontained breathing apparatus (SCBA). Check with your safety department for the specific PPE rules for your specific situation.

17 FOLLOW ALL CGA AND NFPA STORAGE GUIDELINES FOR COMPRESSED GASES Additionally follow all state, local, and facility regulations pertaining to the storage, use and handling of compressed gases. KNOW YOUR GASES AND THE HAZARDS THEY PRESENT Chain or by other approved methods, keep all cylinders secured so they do not fall over. Know the cylinder and what is in the cylinder so that in the event of an emergency you can supply the responding emergency staff with a detailed list of gases in use in the building. MSDS should be on file for all gases on location. All employees should know the location of MSDS and how to read it.

18 DETERMINING YOUR GAS REQUIREMENT What is the gas going to be used for? (i.e. if the gas is to be used in the welding process, then the welding filler materials will have specific shielding gas requirements. If you cannot locate this information on the filler metal packaging, contact the material vendor or manufacturer for details.) Specialty Gas Requirements will be specified by manufacturer of the equipment that the gas will be used with, or by the scientist s or researcher s determination. Since different manufacturers use non-standard terms such as high purity, ultra high purity, etc. to specify different things, it is best to assure quality by requesting gas in specific detail as to your requirements. By example, this would mean requesting a gas to be % pure rather than using terms that are open to interpretation.

19 HIGH PRESSURE CYLINDER SIZES Will the gas be used in its liquid or gas state? Most industrial gases are used in high pressure cylinders of varying size. You are assured the correct cylinder if you order by cubic foot size as detailed above.

20 CGA CONNECTION STANDARDS The Compressed Gas Association (CGA) has established a standardized list of gas fittings to assure that gases cannot easily be connected to non-corresponding fittings and regulators accidentally. A significant safety risk is possible if gas equipment and cylinders are improperly connected. An example of this would be if an oxygen regulator were somehow to be connected to a fuel cylinder, there could be a catastrophic explosion at the regulator resulting in injury or death. To avoid these types of situations the CGA has established a cylinder valve standard to assure operator safety. The standard will not allow an improper connection between a gas cylinder and the gas handling equipment. For example, an oxygen cylinder utilizes a CGA540 Compressed Gas Association designation valve and is design specific to avoid cross connection. An oxygen cylinder can only be connected to a regulator or manifold with a matching corresponding CGA540 fitting. Always make sure that the regulator and valve fittings are compatible.

21 EXPLANATION OF CGA FITTINGS A CGA fitting is the standardized system for the attachment of a compressed gas cylinder to the required regulator or transfer line. The purpose of the standards is to avoid the possibility of installing a regulator on the wrong type of gas cylinder. Each gas has a corresponding CGA number. This number can be used to determine which CGA fitting to use, dictating which regulator and valve to use with your gas. Contact Earlbeck Gases & Technologies to determine your CGA number. There are approximately a dozen commonly used CGA-fittings, with others used for special purposes. Some gases have multiple CGA s for different pressures of the same gas. Common Gases Acetylene (except for small cylinders) 300 Acetylene 510 Acetylene 520 Acetylene 200 Medical Breathing Air 346 Air (non-medical grade) 590 Argon 580 Carbon Dioxide (fitting requires flat washer) CGA Number 320 Helium 580 Hydrogen 350 Methane 350 Nitrogen 580 Oxygen 540 Propane 510

22 HOW TO SELECT YOUR REGULATOR USING CGA Once you have determined your gas s CGA number, you will use the corresponding CGA fitting on your gas cylinder. CGA numbers are typically (but not always) stamped on the regulator just above the threads of the cylinder connection. Some will even state specifically which gas(es) for which they can be used. Common Gas Regulator

23 SELECTING YOUR REGULATOR (CONTINUED) Common Gas Valve Check that the CGA numbers match on your fitting, and always ensure that the regulator appears sound before attaching it to a cylinder. If you have checked the CGA number on a cylinder and regulator and the number is the same and the connections do not fit together readily, the wrong regulator or a defective regulator is probably being used. If this occurs DO NOT force the regulator onto the cylinder. You should not alter a regulator or use an adapter to "make" a regulator fit a tank for which it was not designed. This kind of deliberate tampering with a safety feature could lead to a serious accident. Inspect the cylinder valve threads and valve and if damaged immediately contact Earlbeck Gases & Technologies. If the regulator is damaged it can be sent in for repair or be replaced as is needed.

24 LIQUID BULK CYLINDER VALVES Liquid bulk cylinders may be used in laboratories where a high volume of gas is needed. These cylinders usually have a number of valves on the top of the cylinder. All valves should be clearly marked as to their function. These cylinders will also vent their contents when a preset internal pressure is reached, therefore, they should be stored or placed in service where there is adequate ventilation.

25 SPECIFIC GAS CHARACTERISTICS

26 ARGON Argon is a monatomic, chemically inert gas composing slightly less than 1% of the air. Its boiling point is F ( C). Argon is colorless, odorless, tasteless, noncorrosive, nonflammable and nontoxic. Commercial argon is the product of cryogenic air separation, where liquefaction and distillation processes are used to produce a low-purity crude argon product which is then purified to the commercial product. Argon is used primarily for its properties as an inert gas in applications such as arc welding, steelmaking, heat treating and electronics manufacturing. Argon can be stored in its gaseous state in compressed gas cylinders or in its liquid state in dewars. In a standard 300 cubic foot compressed gas cylinder, you can store 336 cubic feet of argon. Since Argon is inert, special materials of construction are not required. Vessels and piping should be designed to American Society of Mechanical Engineers (ASME) or Department of Transportation (DOT) codes for the pressures and temperatures involved.

27 ARGON HEALTH EFFECTS Since argon is odorless, colorless, tasteless, and non-irritating, it has no warning properties. Humans possess no senses that can detect the presence of argon. Argon is non-toxic and inert. It can act as a simple asphyxiant by displacing the oxygen in air to levels below that required to support life. Inhalation of argon in excessive amounts can cause dizziness, nausea, vomiting, loss of consciousness, and death. Death may result from errors in judgment, confusion, or loss of consciousness, which prevents self rescue. At low oxygen concentrations, unconsciousness and death may occur in seconds and without warning. The hazards associated with argon are asphyxiation and the high pressure of the gas in containers and systems. Personnel, including rescue workers, should not enter areas where the oxygen concentration is below 19.5%, unless provided with a self-contained breathing apparatus (SCBA) or air-line respirator. If oxygen-deficient atmospheres are suspected or can occur, use oxygen monitoring equipment to test for oxygen-deficient atmospheres. Review the appropriate Material Safety Data Sheet (MSDS).

28 ARGON VALVE CONNECTIONS The Compressed Gas Association (CGA) recommends three different connections for argon, depending on the pressure of the container. In addition, a high-integrity connection, also known as a Diameter Index Safety System (DISS) connection, has been assigned to argon. Cylinders containing argon at pressures up to 3,000 psig use a CGA 580 connection; cylinders with pressures between 3,001 and 5,500 psig use the CGA 680 connection; and cylinders with pressures between 5,501 and 7,500 psig use a CGA 677 connection. The DISS connection assigned to argon is 718.

29 OXYGEN Oxygen constitutes approximately 21% of the air we breathe, and has a boiling point of F (-183 C). Oxygen is produced by air-separation processes using either cryogenic liquefaction and distillation or adsorption technologies. Oxygen can be stored and shipped as either a gas or a cryogenic liquid. Due to the compressibility of the molecules, you can fit 337 cubic feet of oxygen in a 300 cubic foot compressed gas cylinder. The principal uses of oxygen are indicative of its strong oxidizing and life-sustaining properties. It s used in medicine for therapeutic purposes and in the metals industry for steel-making and metal-cutting applications. In the chemical and petroleum industries, oxygen is used in the production of fuels and chemicals. O 2 is used in the pulp and paper industry for a variety of applications, including pulp bleaching, black liquor oxidation and lime kiln enrichment.

30 OXYGEN HEALTH EFFECTS Normally, air contains 21% oxygen and oxygen is essentially nontoxic. No health effects have been observed in people exposed to concentrations up to 50% at 1 atmosphere for 24 hours or longer. The inhalation at 1 atmosphere of 80% oxygen for more than 12 hours can cause irritation of the respiratory tract, progressive decrease in vital capacity, coughing, nasal stuffiness, sore throat, and chest pain, followed by tracheobronchitis and later by pulmonary congestion/edema. Inhalation of pure oxygen at atmospheric pressure or less can cause pulmonary irritation and edema after 24 hours. Respiratory symptoms can occur in two to six hours at pressures above 1 atmosphere. One of the earliest responses of the lung is accumulation of water in the interstitial spaces and within the pulmonary cells. This can cause reduced lung function, which is the earliest measurable sign of toxicity. Other symptoms include fever, sinus and eye irritation. When pure oxygen is inhaled at pressures greater than 2 or 3 atmospheres, a characteristic neurological syndrome can be observed. Signs and symptoms include nausea, dizziness, vomiting, tiredness, light-headedness, mood changes, euphoria, confusion, incoordination, muscular twitching, burning/tingling sensations (particularly of the fingers and toes), and loss of consciousness. Characteristic epileptic-like convulsions, which may be preceded by visual disturbances, such as loss of peripheral vision, also occur. Continued exposure can cause severe convulsions that can lead to death. The effects are reversible after reduction of oxygen pressure.

31 SAFETY CONSIDERATIONS OF OXYGEN Fire is the primary hazard associated with gaseous oxygen. Although nonflammable, oxygen readily supports combustion. Explosions may occur in locations where a mixture of fuel gas and oxygen can accumulate. It is important to note that fire chemistry starts to change in oxygen-enriched environments. U.S. OSHA has established the definition of an oxygen-enriched atmosphere as being any atmosphere containing more than 23.5% oxygen. Materials easily ignited in air not only become more susceptible to ignition but also burn with added violence. These materials include clothing and hair which have air spaces that readily trap oxygen. Elevated oxygen levels can be reached very quickly, and all personnel must be aware of the hazard. Systems used in oxygen service must meet stringent cleaning requirements to eliminate any incompatible contaminants. CGA Pamphlet G-4.1, Cleaning Equipment for Oxygen Service, describes cleaning methods for equipment used in oxygen service and CGA Pamphlet O2-DIR, Directory of Cleaning Agents for Oxygen Service, provides comparative information on cleaning agents used to clean oxygen equipment. Also, review the appropriate Material Safety Data Sheet (MSDS).

32 BUILDINGS Adequate ventilation must be provided in areas where oxygen is in use. Keep them clear of combustible materials and post signs indicating the hazard. Also post No Smoking signs. Test the atmospheres in confined work areas for oxygen content. Oxygenenriched atmospheres can cause materials that burn in air to burn more violently or even explosively, and the potential hazard expo- sure to personnel and material is increased. Remember, oxygen has no warning properties! Oxygen cylinders, full or empty, shall not be stored in the same vicinity as flammable gases. The proper storage for oxygen cylinders requires that a minimum of 20 feet be maintained between flammable gas cylinders and oxygen cylinders or the storage areas be separated, at a minimum, by a fire wall five feet high with a fire rating of 0.5 hours. Greasy and oily materials shall never be stored around oxygen; nor should oil or grease be applied to fittings.

33 CO2 CO2 is a nonflammable, colorless, odorless gas. Found in air at concentrations of about 0.03%, carbon dioxide may exist simultaneously as a solid, liquid and gas at a temperature of 69.9 F (-56.6 C) and a pressure of 60.4 psig (416 kpa). At a temperature of 110 F (-79 C) and atmospheric pressure, carbon dioxide solidifies forming dry ice at a density of 97.4 pounds per cubic foot. Because of its low concentration in the atmosphere, air is not a suitable feedstock for carbon dioxide production. Instead, CO 2 is obtained from by-product streams from various manufacturing processes. Bulk quantities of carbon dioxide are usually stored and shipped as liquid under pressure and refrigeration. The most commonly used CO2 cylinder will hold 50 pounds of CO2, which is stored in its liquid state due to having a higher phase transition point.

34 CO2 Although not an inert, carbon dioxide is nonreactive with many materials and is often used for inerting purposes, such as blanketing and purging of tanks and reactors. It s also used as a shielding gas in the arc welding process. Carbon dioxide is the source of the bubbles in soft drinks and other carbonated beverages. In addition to its inert properties, carbon dioxide, as dry ice, is used to freeze a variety of foods. The Compressed Gas Association and the American National Standards Institute have adopted a thread size of inch 14 external right-hand threads per inch designated as valve connection No. 320 for cylinders. This fitting incorporates a flat nipple and fiber washer for making the gas-tight seal.

35 THE PHYSICAL STATE OF CARBON DIOXIDE Most compressed gases are stored in the cylinder in the gaseous state, however, CO2 Is stored in high pressure cylinders at its liquid-vapor (gas) equilibrium point. That is, the cylinder contains both liquid/vapor (gas). CO2 can be withdrawn from a cylinder as either a liquid or a gas. The cylinder is used only in the upright position in order to withdraw a gas. If the CO2 is to be used in its liquid state, a special dip-tube valve must be used and again the cylinder must be used in its upright state. Dip Tube Cylinder

36 TOXICITY OF CO2 Carbon dioxide does not support life and may produce immediately hazardous atmospheres. At concentrations in excess of 1.5%, carbon dioxide may produce hyperventilation, headaches, visual disturbances, tremor, loss of consciousness, and death. Symptoms of exposure in the concentration ranges of 1.5 5% may be highly variable but typical symptoms of carbon dioxide intoxication are listed under Exposure Reactions. If the concentration of carbon dioxide exceeds 10%, exposure may produce profound metabolic aberrations, disturbances of the central nervous system, and cardiac irritability; unconscious- ness can occur without warning, pre- venting self-rescue. At much higher concentrations, carbon dioxide dis- places the oxygen in air below levels necessary to support life.

37 ACETYLENE Pure acetylene is a colorless, highly flammable gas with an ethereal (ether-like) odor, but the odor of the commercial purity grade is distinctively garlic-like. Acetylene can be safely stored and used in cylinders filled with a porous material and containing a solvent (acetone) into which the acetylene has been dissolved. Acetylene, when not dissolved in a solvent (free acetylene), can begin to dissociate (decompose) at pressures above 15 pounds per square inch gauge (psig). The products of dissociation are carbon, in the form of lamp- black, and hydrogen. Considerable amounts of heat are generated by dissociation, which may produce explosions of great violence. Steel and wrought iron are recommended for use in acetylene piping. Rolled, forged, or cast steel, or malleable iron fittings may be used. Cast iron is not permissible for fittings. Unalloyed copper, silver, or mercury should never be used in direct contact with acetylene since there is the possibility of forming explosive acetylides. Wet acetylene will produce explosive acetylides on copper, brass, and aluminum-bronze. Weight (not pressure) is used to determine the amount of acetylene in a cylinder. The tare weight is subtracted from the actual weight, and the difference is multiplied by 14.7 to determine the amount of gas in standard cubic feet.

38 HAZARDS OF ACETYLENE Acetylene is a simple asphyxiant and anesthetic. Acetylene is highly flammable under pressure and is spontaneously combustible in air at pressures above 15 psig. Acetylene cylinders do not contain oxygen and may cause asphyxiation if released in a confined area. Since acetylene is shock-sensitive and explodes above 30 psi, cylinders of acetylene contain acetylene dissolved in acetone. Acetylene cylinders must not be placed on their sides, since the acetone and binders will have dislodged. The result may be formation of an acetylene "pocket" that is subject to polymerization and the possibility that liquid acetone will be released into the regulator. Do not store acetylene cylinders on their side. If an acetylene cylinder has tipped over or was stored on its side, carefully place the cylinder upright and do not use until the liquid has settled to the bottom. The rule of thumb is not to use the cylinder for as many minutes as the cylinder was on its side, up to 24 hours.

39 ACETYLENE CYLINDER SIZES

40 CONTENTS OF ACETYLENE CYLINDER Inside of Acetylene Cylinder Acetylene cylinders contain a filler material and a solvent in addition to the safety relief devices, valves, and protection caps normally supplied on standard-sized hollow steel cylinders for compressed gas service. The shell is manufactured according to Department of Transportation DOT-8 or DOT-8AL specifications. They are used at a service pressure of 250 psi at 70 F. The cylinders are initially hydrostatically tested to pressures two to three times the service pressure. DOT regulations require that the shell of all acetylene cylinders be inspected and requalified on a periodic basis. Typically, for a cylinder manufactured after 1991, the shell is requalified within 10 years of manufacture and every 10 years thereafter. Shells manufactured prior to 1991 must be requalified by 2001, and every 10 years thereafter. Acetone is charged into the cylinder and completely fills the pores of the filler material. Acetone is the solvent which will dissolve the acetylene gas charged into the cylinder. DOT regulations control the amount of acetone and acetylene allowed in each size cylinder.

41 CONTENTS CONTINUED Early cylinders were completely filled with a porous filler material consisting of diatomaceous earth, char- coal, asbestos, and cement. Diatomaceous earth and charcoal are the porous elements, asbestos the strengthening material, and the cement is the binder. Present-day cylinders have a silica lime filler to which some manufacturers add asbestos, charcoal, and other materials to provide a light- weight filler with a higher porosity. The filler materials must be correctly proportioned to provide a homogenous mass in such a manner as to completely fill the shell within the maximum clearances specified by DOT to resist cracking of filler during rough handling of the cylinder, and to obtain the best acetylene charging and discharging capabilities. DOT-8 or DOT-8AL specifications define the requirement of the porosity of the filler material. DOT regulations require that the filler of all acetylene cylinders undergo a one-time inspection and requalification. Requalification of cylinder shell and filler material can only be performed by a facility that has been authorized by and registered with DOT.

42 ACETYLENE VALVES The Compressed Gas Association (CGA) and the American National Standards Institute have adopted a thread size of inch I.D. 14 threads per inch. It is left-hand with internal threads, accepting a bulletshaped nipple. It is designated as Valve Outlet No. 510 and shown in Figure 3. Figure 4 shows the alternate CGA standard valve outlet used on some acetylene cylinders. The valve outlet has a thread size of inch O.D. 14 threads per inch with external right-hand threads.

43 SAFETY DEVICES Protection against excessive temperatures is provided in part by plugs filled with fusible metal which melt at about 212 F. Smaller cylinders may have a small passage in the valve body filled with fusible metal. A fusible plug is illustrated in Figure 5. Never attempt to stop a fusible plug leak by any means. Notify supplier immediately.

44 SAFETY CONSIDERATIONS The picture above shows the damage that can be done to regulating equipment when the basic safety rules governing the handling and use of acetylene and acetylene cylinders are violated. Users of acetylene should know and understand the construction of the cylinders and the properties of acetylene. The following basic safety rules are a guide to storage, handling, and use of acetylene cylinders. 1. Always store and use acetylene cylinders in an upright position to prevent loss of acetone which reduces the cylinder s ability to hold dissolved acetylene. 2. Do not handle cylinders roughly or carelessly to prevent damage to the cylinder or the filler. Dropping cylinders can cause leaks to develop at fuse plugs. Sharp dents in the cylinder can break up the filler in the area of the dent and cause voids where free acetylene can accumulate and decompose at cylinder pressures. 3. Keep cylinders away from external sources of heat. Cylinders are not designed for temperatures in excess of 125 F (52 C).

45 SAFETY CONSIDERATIONS 4. Protect the bottom heads of acetylene cylinders from damp ground. 5. Separate flammable gas cylinders from oxygen and other oxidizing gas cylinders during storage. Separate full acetylene cylinders from empty cylinders. Provide a means of preventing cylinders from falling if accidentally bumped. 6. Use regulators and pressure relief devices when connecting cylinders to circuits having lower pressure service ratings. 7. Always test all regulator, torch, hose, and cylinder connections with a leak check solution before placing acetylene equipment in service. Leaks in a confined area can cause acetylene to collect and readily attain concentrations above the lower flammability limit of 2.5 percent acetylene in the air. 8. Do not use acetylene at pressures above 15 psig, the pressure where decomposition can begin, to avoid explosion and fire hazard. 9. Remove leaking acetylene cylinders to an open area and tag them indicating the danger. Never at- tempt to stop a fuse plug leak. Notify your supplier immediately.

46 SAFETY CONSIDERATIONS 10. In most cases, it is best to allow a burning acetylene cylinder to burn itself out. The exception is small fires at fitting connections which can effectively be extinguished by applying a wet rag, wet asbestos, or similar types of material. Caution must be exercised because the heat from a small flame can melt the fuse plugs and cause a rapid discharge of acetylene which can produce a large fire. Water may be effectively used to prevent involvement of additional cylinders and to protect equipment and property adjacent to burning acetylene cylinders. Adequate distance must be maintained between personnel and burning cylinders because cylinders may rupture. 11. Keep valves closed when cylinders are not in service or empty. At the end of the shift or work day, close the cylinder valve and bleed the pressure off the regulator and torch equipment. Keep cylinder caps on the cylinders provided with threaded spuds when in storage or being moved. 12. If an acetylene cylinder receives a sharp or deep dent, the metal is gouged, or any other mechanical defect, circle the defect with a marking pen to alert the supplier of the defect. Federal Law prohibits persons, other than cylinder manufacturers, from repairing acetylene cylinders. Disposal of unserviceable cylinders should only be attempted by experienced personnel.

47 SAFETY CONSIDERATIONS 13. An acetylene cylinder valve should not be opened more than approximately 11/2 turns. 14. To minimize the withdrawal of liquid solvent, acetylene should be withdrawn from the cylinder at a rate not to exceed 1/10 (one-tenth) of the capacity of the cylinder per hour during intermittent use. For full withdrawal of the contents of the cylinder on a continuous basis, the flow rate should be no more than 1/15 (one-fifteenth) of the capacity of the cylinder per hour. 15. If a cylinder protective cap is extremely difficult to remove, do not apply excessive force or pry the cap loose with a bar inserted into the ventilation openings. Attach a label or tag to the cylinder identifying the problem and return the cylinder to the supplier. 16. Wrenches should not be used on valves equipped with a handwheel. If the valve is faulty, attach a label or tag to the cylinder identifying the problem and return the cylinder to the supplier. 17. Compressed gas cylinders should not be refilled except by qualified producers of compressed gases. 18. Shipment of a compressed gas cylinder filled without the consent of the owner is a violation of Federal Law.

48 If you are ever in doubt or have concerns about your situation in using and handling compressed gases contact Earlbeck Gases & Technologies with your questions and concerns. If you have a compressed gas emergency or hazardous situation at any time contact your local fire department and or emergency services.

49 EARLBECK GASES & TECHNOLOGIES Pulaski Highway Technical Support Hotline (410) C O M P R E S S E D G A S I D E N T I F I C AT I O N, S P E C I F I C S, C O N TA I N E R S A N D H A N D L I N G H A R D WA R E