Recovery Procedures for the R-22 Phaseout

Discover strategies that emphasize proper recovery, recycling and reclamation procedures for R-22 to help preserve the supplies of refrigerant.

View the original article from RSES Journal

Publication date: May 2012

The HVACR market may experience shortages of R-22 in the years to come, according to U.S. Environmental Protection Agency estimates that are based on production quotas and use projections (see Figure 1). One strategy that may help prevent this is switching suitable equipment toan R-22 retrofit, such as R-427A, R-407A or R-407C. Another strategy is to ensure that the available supply of R-22 is notwasted, but rather maintained and reused by applying the “3 Rs”: recovery, recycle and reclaim. While both mechanisms are viable options, this article will focus on the latter. All reclamation efforts need to start with a proactive policy of emissions prevention and elimination, namely, verifying the tightness of systems. Repeated refrigerant top-offs without leak checks are irresponsible and potentially costly. It also is vital to ensure that the entire refrigerant charge is recovered from all systems that are opened during repair, retrofit or end-of-life work. However, refrigerant recovery alone may be insufficient if care is not taken to prevent contamination or mixing of refrigerants in the system or in the recovery equipment.

Recovery equipment

Well-maintained and properly operating recovery machines matched with appropriate recovery cylinders are essential. A good recovery machine will be capable of efficiently recovering both liquid and vapor refrigerant. Higher-end recycling units also should readily remove contaminants, such as non condensable gases (NCGs), oil and moisture. Ideal use of recovery equipment will pull systems into a vacuum, removing most of the refrigerant in the process. For a unit to effectively accomplish this, at minimum, driers and filters need to be replaced regularly to ensure removal of moisture and particulate matter; NCG valves need to be set properly to avoid excessive or inadequate purging; and accumulated oil should be drained. In many instances, recovered refrigerant properly treated by a recycling unit will be acceptable for reuse. EPA regulations permit reuse of refrigerant in systems belonging to the same owner.

While these machines can recover or recycle the refrigerant, they cannot reclaim it. Reclaiming the refrigerant means restoring it to the extent that it would comply with AHRI 700 specs and, thus, be equivalent to new virgin refrigerant. EPA regulations allow the resale of reclaimed refrigerant as new or virgin refrigerant. Another important part of this setup is the cylinder. Recovery cylinders are virtually the same as virgin service cylinders, but subjected to a few different regulations for safety. Recovery cylinders are painted gray on the bottom and bright yellow on top. Dedication to a specific product, like R-22, is recommended to avoid cross contamination. Labeling is critical. The cylinders must be DOT-approved and require recertification every five years. Inspection dates are permanently stamped into the cylinder collar or shoulder for easy verification. Additionally, once a cylinder has been employed for use in refrigerant recovery, it can never again be used for virgin service. As such, virgin refrigerant tanks should not be used in recovery service. Refrigerant suppliers are faced with this issue every time someone inappropriately uses a virgin cylinder for recovery. The cylinder must be either converted to recovery service or scrapped. For safety reasons, care must be taken to not overfill recovery cylinders. Scales should be used during refrigerant transfers to verify that maximum refrigerant fill weights are not exceeded. The proper maximum fill amount of a cylinder can be calculated by multiplying the water capacity (WC) value stamped on the cylinder by the specific gravity (SG) of the product to be recovered (for R-22, SG is 1.19 at 25°C) times the safety factor 0.80. Max Capacity = WC x SG x 0.80. Furthermore, cylinders must be rated for the pressure of the refrigerant in use, or higher. For R-22, this pressure is 240 psig (see Table 1). This rating can be found stamped on the cylinder collar or shoulder. An example of this rating is “DOT-4BW260.” The last number is the pressure rating and, in this case, is 260 psi.

Recovery procedures

Once suitability of the recovery unit and cylinder are established for the product in question, preparations for the refrigerant transfer can begin in earnest. A logical next step is to determine the most appropriate recovery method for your system. Standard liquid/vapor recovery is a popular technique for smaller systems (see Figure 2). Liquid push/pull recovery, a siphon-based variation of liquid recovery, is used for bulk transfers. Vapor recovery is significantly slower, and can lead to higher cylinder pressures and temperatures that require cooling of the tank on hot days. One benefit of vapor transfer is that most circulating oil remains in the system, instead of being removed with the refrigerant. This can be important when considering reusing the recovered refrigerant to service another system. After determining which recovery configuration/connection points will be used, several additional steps can be taken to maximize recovery speed and minimize refrigerant losses. First, review the system piping and make sure that no parts of the system are isolated from the recovery process. Second, use shorter length, larger-diameter hoses (such as 3/8 in. instead of 1/4 in.), and remove Schrader valve cores to increase flow rates. And third, if possible, use a vacuum pump to remove air from the recovery machine/manifold assembly. This can help maintain product purity while reducing emissions from line purging.

Successful recovery operations ensure that systems are evacuated to EPA-established levels. These levels are based on the type/size of system, the manufacture date of the recovery/recycling equipment, and the pressure of the refrigerant (See Table 2). Many recovery machines shut down when prescribed recovery levels (such as 15 in. Hg vacuum) are reached. This helps protect these units from excessive wear caused by prolonged runtimes at high compression ratios. Technicians should actively monitor pressure levels during the refrigerant transfer. Difficulty in reaching/maintaining required evacuation levels may be indicative of several problems. Slowly dropping system pressures may be a sign of trapped liquid refrigerant. Running the system compressor for a few seconds may move the entrenched product and allow for expedited recovery. Rapidly climbing system pressures after recovery unit shutdown may result from oil out-gasing. Warming the compressor with a heat gun may help resolve this issue. Exceptions to the evacuation requirements have been established for leaking systems. These involve isolating leaking components, and recovery levels that will not lead to significant refrigerant contamination (such as air).

Reclaim or reuse

Refrigerant removal is not the end of the recovery process. The decision to reuse or reclaim dictates what happens next. Systems evacuated for repairs can have the original refrigerant reinstalled. However, decommissioning of a system is another story. As was stated earlier, recovered refrigerant may be used to service systems belonging to the same owner. As such, a comprehensive recovery strategy should consider the number of systems in question, their useful life and service requirements, as well as storage and transportation of the refrigerant.

The condition of recovered product also should be examined. While high-end recovery machines may “recycle” the refrigerant, they have limitations.

Refrigerant from a compressor burnout or other highly contaminated system might be best left for reclaim. Moisture indicators and acid test kits can alert technicians to potentially serious problems with the refrigerant or system. For very large systems taken out of service, where the recovered product is intended for reuse, lab analysis of the refrigerant is often recommended.

Conclusions

The phaseout of R-22 raises many issues for those involved in HVACR service. While sometimes challenging, the best practices described here are necessary to ensure safety, eliminate emissions and reduce costs. By enacting strategies that emphasize proper recovery, recycling and reclamation procedures,the HVACR industry will help preserve the supplies of refrigerants throughout this transition.

Lists of approved refrigerant reclaimers and refrigerant drop-off locations are available on the EPA’s website. More information on refrigerant recovery/recycling equipment is available through AHRI.

Gus Rolotti is the Technical Marketing Director of the Fluorochemicals Division of Arkema Inc. He has managed refrigerant issues for 26 years at Arkema’s North American headquarters and R&D center in King of Prussia, PA. He can be reached via e-mail at gus.rolotti@arkema.com. Stephen Spletzer is the Senior Technical Sales Engineer for Arkema’s Forane Refrigerants team. He has spent the last 17 years in applications, and specializes in the testing, characterization, and retrofitting of air-conditioning and refrigeration systems. Additionally, Spletzer has actively participated in transitioning other refrigerant-related industries to alternative solutions. He can be reached via e-mail at stephen.spletzer@ arkema.com.

For more information, visit www.arkema.com.