Low-Cost Retrofit Concepts

Refrigerant strategy options are largely based on containment plus the Three R's - Recover, Recycle, Reuse. There are many ways to mitigate refrigerant loss. First, users should develop maintenance and refrigerant-use logs to track these costs. The following low cost steps may be appropriate depending on the age, type, and size of the cooling equipment:

• Check for refrigerant leaks frequently
  
• Replace or repair all leaky fittings and valves
  
• Add isolation valves to allow safe refrigerant evacuation before repair
  
• Install refrigerant valves with cap, and really use them.
  
• Make sure valve packings and seals are rated for the refrigerant used.
  
• Use back-seating valves to minimize valve-stem leakage
  
• Use dual-relief valves (in addition to rupture discs) to allow valve repairs during system operation.

After implementing these low-cost options, carefully consider the next step involving additional investments in the existing equipment. These concepts include:

• With CFC-11 chillers, make sure the chiller has the improved, high efficiency purge unit. If it doesn't, consider having one installed. Purge units are the largest source of CFC-11 release; some of the old ones release from 4 to 10 pounds of CFC-11 per pound of air. The new units reduce this loss to a minimum -- some as low as 0.005 pounds CFC-11 per pound of air. This is less than 1% per year of the refrigerant charge.

• With CFC-11 and HCFC-123 chillers, make sure the chiller is equipped with a repressuring system to facilitate leak detection. Again, if it's not, consider installing one. A vessel repressuring system is used with low-pressure refrigerant systems that operate at a vacuum. This system prevents a vacuum condition during shutdown periods and thereby reducing air infiltration by heating the refrigerant and thus pressurizing the system. This cuts the time and expense of leak-testing by eliminating the pressurization with an inert gas (e.g., nitrogen) and limiting refrigerant losses during purging procedures. It can also help stop leaks until they can be located and corrected.

• Use a refrigerant recovery device to drain refrigerant during maintenance and non-cooling seasons.

• Use a refrigerant transfer-and-storage receiver system.

• Install and use an oxygen sensor or vapor detector that will provide a warning when refrigerant is leaking, and comply with the new safety codes.