Use of recovery/recycle units (Figures 1-8 and l -9) is required by U.S. Environmental Protection Agency (EPA) regulations. Technicians who service and dispose of air conditioning and refrigeration equipment must recover the refrigerant instead of venting it to the atmosphere. With the exception of extremely small releases of refrigerant such as occurs when disconnecting service hoses, a technician who knowingly releases or vents refrigerant to the atmosphere is in violation of this EPA regulation. Before opening any system for service or repair, the refrigerant must be collected using an approved recovery device or the charge must be isolated in another part of the system. To insure compliance, EPA regulations require that contractors who perform on-site recovery or recycling of refrigerant certify that they own and a re properly using certified recovery or recycling equipment.
The descriptions given in the following paragraphs emphasize the recovery and recycle units used mainly to service
residential and small commercial air conditioning and refrigeration equipment. When servicing larger commercial systems such as centrifugal chillers, different recovery and containment devices are used because of the larger volumes of refrigerant. Service training materials on recovery/recycle devices for large systems are readily available.
Recovery and recycle units are available in various sizes, types, and prices. They can be stand a lone recovery or recycle units or combined into one unit that accomplishes both functions.
As shown in Figure 1-10, many stand alone recovery and recycle units are designed so they can be connected together to form an integrated recovery/recycle unit.
Recovery units by themselves do not provide for any cleaning or filtration of the refrigerant. They are used at the job site to remove (recover) refrigerant from a system and store it in an approved external container. The normal procedure is to test the recovered refrigerant for moisture and/or acid to determine if it can be reused in the same system as is, or if it needs to be processed through a recycling unit to remove contaminants before reuse.
Recycling is typically performed using single or multiple passes through filter core driers or similar devices that remove moisture, acid, and particles. Figure 1-11 shows a recovery/recycle unit connected for recycle operation. After the refrigerant is recycled, it may be returned to the same system or to another system belonging to the same owner. Combined recovery/recycle units perform all the processes described for both recovery and recycle units.
When selecting a recovery or recovery/recycle unit, make sure it can perform the functions needed for your particular service application. Once recovery/recycle equipment is obtained, maintain it according to the manufacturer’s instructions, especially with regard to changing filter devices and d raining oil. If the equipment is used to recover different types of refrigerants, it must be properly serviced to avoid refrigerant mixing.
Some of the standard features of recovery/recycle units used in residential and light commercial applications are:
• The ability to process R-12, R-22, R-500, R-502, and/or R-134a refrigerant as a liquid or a vapor.
• The ability to test refrigerant for moisture and acid contamination.
• Processing time (rate of recovery) of 1.5 to 3 lbs. of vapor/minute or 3 to 5 lbs. of liquid/minute. Refrigerant recovery efficiency range of 80 to 96 percent. The maximum recovery efficiency is the percentage of refrigerant that the equipment is capable of recovering from a unit. It is directly related to the depth of vacuum that the unit can achieve. Units that can evacuate a system to a negative pressure as low as 20 inches of mercury (in. Hg) are common.
• Reusable refrigerant cylinder capacity of at least 50 lbs. and automatic shutoff when the cylinder is 80 percent full.
• Hermetic, reciprocating, o r rotary compressor. Power input of 110 to 120 VAC. Easy operation in manual mode. Many are available with automatic microprocessor controlled operation.
• Handles/lifting bars and wheels that make the unit easy to transport in and out of service trucks and work sites. Most recovery/recycle units typically weigh between 75 and 160 lbs. Individual recovery o r recycle units weigh about 50 lbs.