Steps to reduce refrigerant gas leak and its dangers to environment.

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OZONE DEPLETION POTENTIAL
     Ozone depleting substances (ODS) vary in their capacity to destroy ozone molecules. So scientists have developed a method of characterizing the relative depletion caused by different ODS. ODP is the ratio of calculated ozone column change for each mass unit of a gas emitted into the atmosphere relative to the calculated depletion for the reference gas CFC 11 ( ODP =1)

GLOBAL WARMING POTENTIAL
      Global warming potential (GWP) is a measure of how much a given mass of a gas contributes to global warming. GWP is a relative scale which compares the amount of heat trapped by green house gas to the amount of heat trapped in the same mass of carbon-di-oxide.

ODP and GWP of conventional refrigerant gas are as follows:-

      Gas                                                       ODP                                   GWP

  • R-11                                               1.0                                        4000
  • R-12                                               1.0                                        2400
  • R-22                                               0.5                                        1700
Alternate gases available on board which are used in refrigeration systems are :-

       Gas                                                        ODP                                             GWP   
  • R134a                                                 0                                                    1300
  • R143 a                                                0                                                     4300
  • R152 a                                                0                                                      120
  • R 404 A                                              0                                                     3784
  • R 407 C                                              0                                                      1653
  • R 410 A                                              0                                                      1975
R 134a is long term replacement for R-12 and is best performed in medium and high temperature application.
R 410A is twice as efficient as R-22 but is recommended for new systems only.
R 407C is suitable for medium and high temperature application. And is suitable for new system and for R-22  change over.
R 404A is suitable for low and medium temperature application. It is suitable for new marine system.

To minimize the release of refrigerant gas from plant following steps should be taken:
During operation ---
  • During normal operation loss of refrigerant from leaking joints, seals, gaskets and cracked pipe should be checked.
  • Loss of refrigerant from safety relief valve.
  • Damaged mechanical seals on open type compressor are frequent source of refrigerant leaks. A clean dry system is essential for prolonged mechanical seal effectiveness to eliminate emission. Compressor oils used for HCFC and HFC will absorb moisture readily and must keep dry to prevent refrigerant decomposition.
  • Excessive vibration and excess water pressure should not be allowed in the condenser to avoid tube failure.
  • Leak testing should be carried out regularly. Testing can be done by bubble testing with soap solution or by electronic leak detection.
During maintenance ----
  • Loss of small quantities of refrigerant from charging lines during charging.
  • Before doing any maintenance gas should be recovered and not leaked in environment.
  • During maintenance compatible gaskets should be used which are compatible with the gas and oil used in the system.
  • Evacuate the hoses before disconnecting temporary equipment.
  • Practice recovery and recycling when recharging dryers and filters.                 

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