Cylinder Safety Rules
Handling of Compressed Gas Cylinders
- Avoid dragging or sliding cylinders, even for short distances. Cylinders should be moved by using a suitable hand truck.
- Never drop cylinders or permit them to strike violently against each other. When cylinders are moved, they should not be subjected to abnormal mechanical shocks that may cause damage to their valves, their pressure relief devices, or to the cylinders themselves.
- The cylinder protection cap should always be in place when moving a cylinder or until the cylinder has been secured against a wall or a bench, placed in a cylinder stand, and is ready to be used. Cylinders should always be secured when not in use.
- Never tamper pressure relief devices in valves or on the cylinders.
- Never permit oil, grease, or other readily combustible substances to come in contact with oxygen cylinders, valves, or regulators.
- Do not remove the product identification label or change the cylinder color.
- When returning empty cylinders, close the valve before shipment. Leave some positive pressure in the cylinder. Replace any valve outlet and protective caps originally shipped with the cylinder. Mark and label the cylinder EMPTY.
- Compressed gas cylinders should not be refilled except by qualified producers of compressed gases.
- Shipment of a compressed gas cylinder which has not been filled by the owner, or filled without the consent of the owner, is a violation of U.S. law.
- Never lift a cylinder by the cap except with an approved cylinder cart designed for this purpose.
- Do not use aluminum regulators in oxygen service.
Storage of Compressed Gas Cylinders
- Always store cylinders in the upright position. Cylinders should be assigned to a definite area for storage. Segregate full and empty cylinders. The area should be dry, cool, well ventilated, and preferably, fire-resistant. Keep cylinders protected from excessive temperatures by storing them away from radiators and other sources of heat. Cylinders may be stored in the open, but they should be protected against extremes of weather and from damp ground to prevent rusting. In general, cylinders should be secured in storage.
- Smoking or open flames should be prohibited in oxygen or flammable gas cylinder storage areas.
- Oxygen cylinder storage must be separated from flammable gas storage areas or combustible materials by at least 20 feet or by a noncombustible wall.
Uses of Compressed Gas Cylinders
- Know and understand the properties, uses and safety precautions of the gas before using the gas and/or associated equipment. Consult Material Safety Data Sheets and Safetygrams for the particular gases being used.
- The cylinder decal or label is the only positive way to identify the gas contained in a cylinder. Color coding of cylinders is an identification method used for the convenience of the gas supplier only.
- Do not use cylinders as rollers for moving material or other equipment.
- Never use a cylinder to store other materials or to mix gases supplied or vented from the user’s system.
- Never use oxygen as a substitute for compressed air.
- No part of a cylinder should be subjected to a temperature above 125°F (52°C). Prevent sparks or flames from welding or cutting torches or any other source from coming in contact with cylinders. Do not permit cylinders to come in contact with electrical circuits or apparatus.
- Use regulators and pressure relief devices when connecting cylinders to circuits of lower pressure service ratings. Only regulators approved for the specific gas should be used. Open cylinders before adjusting pressure on the regulator.
- Always open all cylinder valves slowly.
- At the end of a work shift or any time an extended period of non-use is anticipated, valves should be closed on cylinders and all pressure released from equipment connected to the cylinder. The user must ensure that any product remaining in the downstream equipment, once the cylinder valve is closed, is vented or disposed of in accordance with laws and proper safety methods.
- Use check valves or traps to prevent backflow of water or other contaminants if backflow can occur into the cylinder. If backflow occurs, mark the cylinder CONTAMINATED. Notify the supplier immediately.
- 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 to supplier.
- Wrenches should not be used on valves equipped with a handwheel. If you experience any difficulty operating a cylinder valve, discontinue use and contact the supplier. If the valve is faulty, attach a label or tag to the cylinder identifying the problem and return the cylinder to the supplier.
- Use only oxygen-compatible threading compounds such as Teflon™ tape on valve threads for oxygen service.
Handling of Acetylene Cylinders
Acetylene cylinders require some special practices:
- Never use steam or boiling water to loosen an acetylene valve or to clean a cylinder. The safety plug fusible metal melts at approximately 212°F, the boiling point of water.
- Do not peen fuse plugs to stop leaks.
- Always open and close valves slowly. Never use acetylene at pressures in excess of 15 psi; for more volume, use a larger hose.
- Do not expose cylinders to temperatures above 125°F to prevent them from becoming liquid full.
- Full cylinders should always be stored upright.
Handling of Cryogenic Liquids
Many of the safety precautions observed for compressed gases also apply to cryogenic liquids. Two important properties distinguish them from compressed gasses, and both present additional potential hazards.
- All cryogenic liquids exist at very low temperatures. The common cryogenic liquids include argon (-302°F), hydrogen (-423°F), nitrogen (-320°F), and oxygen (-297°F). Their cold boil-off vapor rapidly freezes human tissue. Materials such as carbon steel, plastics, and rubber become brittle or even fracture under stress at cryogenic temperatures. Proper material selection is important. Cold burns and frostbite caused by cryogenic liquids can result in extensive tissue damage.
- All cryogenic liquids produce large volumes of gas when they vaporize. Liquid nitrogen, for example, will expand approximately 700 times as it vaporizes; other liquids expand even more. If these liquids vaporize in a sealed container, they can produce elevated pressures that could rupture the vessel. For this reason, pressurized cryogenic containers are usually protected with multiple pressure relief devices. Vaporization of inert cryogenic liquids (except oxygen) in a confined area can form asphyxiation atmospheres. However, vaporization of liquid oxygen in a confined area can produce an oxygen-rich atmosphere, and as an oxidant, enhance combustion. Liquid hydrogen can form an extremely flammable mixture with air.
Cryogenic liquids should be handled only in containers, i.e., liquid cylinders, designed for that purpose.
Containers must be clean, especially for oxygen service, and special containers should be reserved for oxygen use only. Liquid cylinders may be made from 300 series stainless steel, copper, or 9% nickel steel.
Most cryogenic liquids are odorless, colorless, and tasteless when vaporized. When they are exposed to the atmosphere, the cold boil-off gases condense the moisture in the air, creating a highly visible fog. Always handle these liquids carefully. Boiling and splashing always occur when changing or filling a warm container with cryogenic liquid or when inserting objects into these liquids. Never touch uninsulated pipes or vessels containing cryogenic liquids; flesh will stick to extremely cold materials, even nonmetallic ones.
Safety glasses are recommended during transfer or normal handling of cryogenic liquids. If splashing or spraying can occur, a faceshield should be worn for additional protection. Wear loose-fitting, dry leather gloves when handling objects that come into contact with cryogenic liquids and vapor. Trousers should be worn on the outside of boots or work shoes. It may be advisable to wear additional special clothing, depending on the application.
Oxygen Compatibility and Cleaning
Oxygen equipment and systems, including cylinders, valves, regulators, piping, and other components, must be certified as compatible with and cleaned for use in oxygen service.
Failure to adhere to compatibility and cleanliness standards may result in fire or explosion. Oxygen systems should be designed and constructed only under the supervision of competent engineering personnel thoroughly familiar with the procedures necessary to assure safe system design, installation, and operation.
Medical System Warning
Medical oxygen systems and regulators should be used only by persons who have been properly trained in administering oxygen. This equipment is intended for use as directed by a medical professional. Use only therapeutic (medical) grade oxygen with medical oxygen regulating equipment. NOTE: Breathing of oxygen in high concentrations for long periods of time or at elevated pressures may be harmful.