There are specific regulations about the handling of refrigerants and their containers as a result of the Clean Air Act. These regulations require that specific types of cylinders be used for the recovery, storage, and/or transportation of refrigerants.
Refrigerant Cylinders — Refrigerant cylinders (Figure 3-6) are considered pressure vessels and must comply with all state and federal laws governing their use and construction. Medium pressure and high-pressure refrigerants come in metal cylinders that vary in shape and size. Medium-pressure and high-pressure refrigerants such as CFC-12, HCFC-22, HFC-134a, CFC-500, and CFC-502 come in either returnable or disposable metal cylinders that range in capacity from about one pound of refrigerant to 1,000 pounds or more. The labels on the cylinders are marked and the cylinders are color-coded to avoid confusion. Refrigerant cylinder labels also include important safety and health information.
Disposable Cylinders — Disposable cylinders are one-way cylinders. That is, once emptied, their use is over. They are made from steel; therefore, they can rust. Rust can weaken the container so that it can no longer hold pressure. To prevent rust, protect the painted surfaces of disposable cylinders by keeping them in the original carton during use and transportation, and always store them in dry locations. Never allow nearly-full disposable cylinders to lay around unused for extended periods of time. Over time, rough handling or excessive heat could cause them to explode, especially if weakened by rust or corrosion.
Once empty, disposable cylinders are recycled as scrap metal. Be sure that the cylinder pressure is released to zero pounds pressure, then render the cylinder useless by puncturing the mpture disk or breaking off the shutoff valve.
Returnable/Reusable Cylinders — Returnable/reusable cylinders are made to be returned to the refrigerant distributor or manufacturer for refilling. They are well constructed, enabling them to withstand constant handling. Returnable/reusable cylinders have shutoff and relief valves and a protective cap that should always be screwed over the valve when moving the cylinder and during shipment. Never use a returnable/reusable cylinder as a recovery cylinder.
Usually, returnable/reusable cylinders are labeled to indicate three values of cylinder weight (Figure 3-7). These values are important because they can be used by the service technician to find the amount of refrigerant remaining in a cylinder. They are more important to the manufacturers and/or distributors of refrigerant because they use these weights to prevent overfilling a cylinder, which might cause an explosion.
The first weight value you should be aware of is tare weight. Tare weight is the empty weight of the cylinder.
The next value is gross weight. Gross weight is the combined weight of the cylinder (tare weight) plus the weight of the refrigerant when the cylinder is full. Be aware that the term full cylinder actually means a cylinder that is filled to 80% of liquid capacity, based on the highest expected ambient temperature, which is generally accepted to be 130° F. The remaining 20% of the volume must be available to allow room for expansion.
The last weight value o f importance is net weight. Net weight is the weight of the contents in the cylinder. For example, when ordering 30 pounds of refrigerant from a supplier, we are actually talking about the net weight. Manufacturers design cylinders so that when the full net weight is reached, 20% of the cylinder volume is remaining for expansion.
Refillable Recovery Cylinders — The refillable recovery cylinder is normally supplied with recovery or recovery/recycle units such as the one shown in Figure 3-8. Refillable recovery cylinders in the capacity range of 15 to 50 pounds are commonly used. The one shown is a 50-pound (22.7 kg) cylinder. Refillable recovery cylinders can be recognized by their color and valve arrangement. They are yellow on top with a special valve that allows liquid or vapor refrigerant to be added or removed from the cylinder.
Recovery cylinders must always be used when recovering or recycling and/or charging used refrigerants. According to government regulations, the cylinders must be labeled to properly identify the type of refrigerant.
Never use a disposable or reusable cylinder for recovery. You should have a separate recovery cylinder for each type of refrigerant you intend to recover. Always read the cylinder label to make sure that the cylinder is intended for use with the type of refrigerant you want to recover. I f you are recovering different refrigerants, DO NOT MIX THEM . If refrigerants get mixed, they must go through an expensive processing procedure, or may require incineration.
Be careful not to overfill the cylinder. Never exceed the cylinder’s maximum gross weight. The maximum capacity of any cylinder is 80 percent by maximum net weight, based on the highest expected ambient temperature, which is generally accepted to be 130° F. Most refillable recovery cylinders have a built-in float switch that provides overfill protection to turn off the associated recovery/recycle unit if the cylinder is full. The use of recovery/recycle equipment and recovery cylinders equipped with this feature is strongly recommended.
Handling Cylinders — The precautions and procedures for handling cylinders are discussed in detail in Section 2 of this manual.
The main precautions are repeated here:
• Do not drop, dent, or abuse refrigerant cylinders.
• Keep disposable cylinders in original cartons as an added measure of protection.
• Always secure cylinders in place to prevent them from tipping over or being damaged when moving around.
• Replace the protective cap, if available, to protect the cylinder valve.
• Always use a proper valve wrench to open and close the valve.
• Never heat a cylinder with an open flame or place an electric resistance heater in direct contact with it. If it is necessary to warm a cylinder, do It by placing the cylinder in a pan of warm water. Do not exceed 125° F on any part of the cylinder.