4 Equipment, Cylinders, and Safety

Recovery equipment and setup

Recovery removes refrigerant from an appliance and stores it in an external container; it does not necessarily clean or test the refrigerant. Equipment must be certified for the applicable use and refrigerant. EPA standards vary by equipment type, and equipment for small appliances has specific performance requirements. Check the equipment’s certification label and manufacturer instructions before use.

Operating the recovery setup

A typical setup includes a recovery machine, an approved refillable recovery cylinder, hoses and fittings, and a scale. A filter-drier may be used to protect equipment and reduce contaminants. Use hoses and connections compatible with the refrigerant and the pressures involved. Keep hoses as short and large in diameter as practical to reduce flow restrictions.

Follow the machine’s required connection and operating procedure, and keep refrigerants separate. Mixing refrigerants can make recovery and reclamation difficult. Recovery speed can depend on the machine’s capacity, hose length and diameter, restrictions, and refrigerant temperature. For example, a long, narrow hose can slow transfer compared with a short, larger-diameter hose.

Use the recovery method and endpoint required for the appliance and applicable rules. Do not vent refrigerant to speed the job; intentional venting during service is prohibited.

Interpreting pressure and temperature

For a refrigerant at saturation, pressure and temperature are linked: at a given pressure, the refrigerant has a corresponding saturation temperature, and vice versa. A pressure–temperature chart lets a technician estimate saturation temperature from pressure or check whether a pressure reading is plausible for a measured temperature. Different refrigerants have different pressure–temperature relationships, so use the chart for the specific refrigerant. For blends with temperature glide, check whether the chart calls for dew-point or bubble-point values.

In a closed cylinder containing both liquid and vapor, pressure is governed largely by the refrigerant’s temperature while liquid remains. Warming the cylinder raises its saturation pressure, while cooling it lowers the pressure. A high cylinder pressure can therefore result from high temperature and does not, by itself, prove the cylinder is overfilled.

Checking for noncondensables

Pressure and temperature can help identify possible noncondensables. Allow the cylinder to reach a stable temperature, then compare its measured pressure with the expected saturation pressure for the identified refrigerant at that temperature. A pressure notably above the expected value may indicate air or another noncondensable. Use the correct procedure and instruments before drawing a conclusion.

Selecting and handling cylinders

Use an approved, refillable recovery cylinder that is in serviceable condition. Before use, inspect it for damage, corrosion, legible markings, and valid inspection or qualification status. Secure it upright during handling and transport, protect its valve, and keep it away from heat. Clearly identify the refrigerant; do not put different refrigerants or unknown refrigerant together in one cylinder.

Do not confuse a recovery cylinder with a disposable refrigerant container. Never refill a disposable cylinder. Traditional Section 608 study materials commonly describe recovery cylinders as gray with a yellow top, but color alone is not a reliable way to identify the contents or determine whether a cylinder is approved. Read the cylinder’s markings and labels.

Filling limits and expansion

Do not fill a recovery cylinder beyond $80\%$ of its capacity. The remaining space allows for liquid expansion as the cylinder warms. Use a scale to monitor the amount transferred and follow the cylinder’s markings and equipment instructions. Do not rely on pressure alone to determine how full a cylinder is: while liquid and vapor coexist, pressure mainly reflects temperature, not the quantity of refrigerant. Because liquid occupies more volume as it warms, an overfilled cylinder can become dangerously pressurized as the liquid expands. Never heat a cylinder with a torch or another uncontrolled heat source.

Exposure and pressure-testing safety

Refrigerant exposure can displace oxygen and cause asphyxiation, while liquid refrigerant can cause frostbite. Avoid breathing refrigerant vapor and prevent liquid from contacting skin or eyes. Wear appropriate eye protection and gloves, work with adequate ventilation, and follow the refrigerant and equipment safety information. In an emergency involving a suspected oxygen-deficient atmosphere, do not enter without appropriate training and respiratory protection.

For pressure testing or leak detection, use dry nitrogen, never oxygen or compressed air. Oxygen or air mixed with oil and exposed to pressure can create a fire or explosion hazard. Use a pressure regulator and a relief device with nitrogen, and do not exceed the equipment’s rated test pressure. Keep cylinders secured, handle them without dropping or dragging them, and follow applicable manufacturer and workplace procedures.