Gas Categories
Corrosive – Gases that corrode material or tissue with which they come in contact, or do so in the presence of water, are classified as corrosive. They can also be reactive and toxic and/or flammable or an oxidizer. Most are hazardous in low concentrations over long periods of time. It is essential that equipment used for handling corrosive gases be constructed of proper materials. Use check valves and traps in a system where there is a possibility that water or other inorganic materials can be sucked back into the cylinder. Due to the probability of irritation and damage to the lungs, mucus membranes and eye tissues from contact, the threshold limit values of the gas should be rigidly observed. Proper protective clothing and equipment must be used to minimize exposure to corrosive materials. A full body shower and eye wash station should be in the area. Personnel must be familiar with the work area. Aisles should always be clear and unobstructed in the event that the gas makes contact with the eyes and vision is disrupted.
Flammable – Gases that, when mixed with air at atmospheric temperature and pressure, form a flammable mixture at 13% or less by volume, or have a flammable range in air of greater than 12% by volume regardless of the lower flammable limit, are classified as flammable. They can be high-pressure, toxic, reactive and displace oxygen in air. A change in temperature, pressure or oxidant concentration may vary the flammability range considerably. All possible sources of ignition must be eliminated through proper design of facilities and the restriction of smoking and open flames. Use a vent line made of stainless steel, purge with an inert gas and use a flash arrester. It is important to have(and know how to use) a fire extinguisher in the area where flammable gases are used and stored, as well as a hand-held flammable gas detector to determine if flammable gases are building up. This gas detector can also be used as a leak detector on the lines of the equipment being used. Always remember that the source of flammable gas must be closed or shut-off before attempting to put out a fire involving flammable gases.
Inert – Gases that do not react with other materials at ordinary temperature and pressure are classified as inert. They are colorless and odorless, as well as nonflammable and nontoxic. The primary hazard of these gases is pressure. These gases are often stored at pressures exceeding 2,000 psi (138 bar). Also, they can displace the amount of oxygen necessary to support life when released in a confined place. Use of adequate ventilation and monitoring of the oxygen content in confined places will minimize the danger of asphyxiation. Always wear safety glasses and safety gloves when working with the lines to avoid absorption of the gas through the skin.
Oxidant – Gases that do not burn but will support combustion are classified as oxidants. They can be high-pressure, toxic and reactive, and can displace breathing oxygen from air (except O2itself). All possible sources of ignition must be eliminated when handling oxy-gen and other oxidants as they react rapidly and violently. Do not store combustible materials with oxidants. Do not allow oil, grease or other readily combustible materials to come in contact with the cylinder or equipment used for oxidant services. Use only equipment that is intended for this type of service. Use only a regulator that has been clearly prepared for use with this type of service this regulator should be labeled “Cleaned for O2 Services.”
Cryogenic – Gases with a boiling point below -130°F (-90°C) at atmospheric temperature are considered cryogenic gases. They are extremely cold and can produce intense burns (similar to heat burns) and tissue necrosis may be even more severe. They can be non-flammable,
flammable or oxidizing. Cryogenic liquids can build up intense pressures. At cryogenic temperatures, system components may become brittle and crack. Never block a line filled with cryogenic liquid as a slight increase in temperature can cause tremendous and dangerous buildup of pressure and cause the line to burst. The system should also be designed with a safety relief valve and, depending upon the gas, a vent line. To protect from injury, always wear gauntlet gloves to cover hands and arms, and a cryogenicapr on to protect the front of the body. Wear pants over the shoes to prevent liquids from getting trapped inside your shoes. Wear safety glasses and a face shield as cryogenic liquid tend to bounce upward when spilled.
Toxic or Poison – Gases that may produce lethal or other harmful effects on humans are classified as toxic or poison. They can be high pressure, reactive, nonflammable or flammable, and/or oxidizing in addition to their toxicity. The degree of toxicity and the effects will vary depending on the gas; however, death will occur when breathed in sufficient quantities. Read your MSDS thoroughly before use and consult with your Representative or a more
knowledgeable coworker who has handled the gas before. Never work alone with toxic gases a backup safety person is essential! Inspect the entire assembly or system that will contain the gas and thoroughly test it for leaks with an inert gas before use. Purge all lines with an inert gas before opening the cylinder valve or breaking connections.
Use toxic gases in a well-ventilated area. For safety purposes and to minimize exposure, it is important to have gas detectors. It is preferable that the breathing apparatus be stored in a safe area immediately adjacent to the work area, so that in the event of an emergency, a person can go directly into the area and close the door and safely put on the apparatus. Full body showers, eye washes, fire alarms and firefighting equipment should be in the area of use and readily accessible. Refer to your local building code for storage and use requirements for toxic gases. Keep your inventory of toxic or poison gases to a minimum. When a project is completed, return leftover cylinders to Scott. They should never be stored for possible future use. This might result in accidental removal of cylinder labeling, making it an unnecessary hazard and greatly increasing the cost of proper disposal.
Cylinder: Storage and Use
Storage
Storage Area – Store gas cylinders in a ventilated and well-lit area away from combustible materials. Separate gases by type and store in assigned locations that can be readily identified. Store cylinders containing flammable gases separated from oxygen cylinders and other oxidants, by a fire-resistant wall (having a fire-resistance rating of at least a half-hour) or locate them at least 20 feet (6.1 meters) apart from each other. Poison, cryogenic and inert gases should be stored separately. Labels, decals or other cylinder content identification should not be obscured or removed from the gas cylinder. Cylinders should also be stored where they can be protected from tampering by unauthorized personnel.
Storage Area Conditions – Storage areas should be located away from sources of excess heat, open flame or ignition, and not located in closed or subsurface areas. The area should be dry, cool and well-ventilated. Use of a vent hood does not provide for a safe storage area except for when a cylinder is actually in use. Outdoor storage should be above grade, dry and protected from the weather.
Securing Cylinders in Storage – The risk of a cylinder falling over and possibly shearing off its valve demands that a cylinder always be held in place with a chain or another type of fastener such as a bench or wall clamp. While in storage, cylinder valve protection caps MUST be firmly in place.
Cylinder Temperature Exposure – Cylinder temperature should not be permitted to exceed 125°F (52°C). Steel cylinders are typically used for more corrosive products. Though they are more durable than aluminum cylinders, they should not be stored near steam pipelines or exposed to direct sunlight. Aluminum cylinders are used for increased stability of mixtures containing certain components and they can be damaged by expo-sure to temperatures in excess of 350°F (177°C). These extremes weaken the cylinder walls and may result in a rupture. Do not apply any heating device that will heat any part of the cylinder above 125°F (52°C). Empty Cylinders – Arrange the cylinder storage area so that old stock is used first. Empty cylinders should be stored separately and clearly identified. Return empty cylinders promptly. Some pressure should be left in a depleted cylinder to prevent air backflow that would allow moisture and contaminants to enter the cylinder.
Usage
Labeling – If a cylinder’s content is not clearly identified by proper labels, it should not be accepted for use.
Securing Cylinders Before Use – When a cylinder is in use, it must be secured with a fastener. Floor or wall brackets are ideal when a cylinder will not be moved. Portable bench brackets are recommended when a cylinder must be moved around. Stands are available for small cylinders as well as for lecture bottles.
Initiating Service of Cylinder – Secure the cylinder before removing the valve protection cap. Inspect the cylinder valve for damaged threads, dirt, oil or grease. Remove any dust or dirt with a clean cloth. If oil or grease is present on the valve of a cylinder that contains oxygen or another oxidant, do NOT attempt to use it. Such combustible sub-stances in contact with an oxidant are explosive.
Know and understand the properties and hazards associated with each gas before using it!
Identification – label
Personal protective equipment
Generally required:
Sometimes required:
Compressed Gas Cylinder Colour Codes
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