Grasso Air Purger
Non-condensable gases cause considerable loss of efficiency. Air or other non-condensable gases can dissolve in the refrigerant and come into circulation in the refrigeration system, causing even in small concentrations a significant increase in condensing pressure, resulting in a considerable loss of efficiency.
Any refrigeration systems must therefore be kept as free as possible from non-condensables. The most effective way of doing this is by automatic purging, as this responds immediately to any entering of non-condensables in the system. Conventional (manual) purging is always accompanied by loss of costly and polluting refrigerant. The Grasso self-limiting and cooled Automatic Purger reduces this loss to a minimum.
Five ways in which non-condensables enter the system
- The refrigerant, when delivered, may contain non-condensables up to 1.5%
- For service and maintenance certain parts of the refrigeration plant are frequently opened, causing air to penetrate into the system. Oil changing and recharging with refrigerant have the same effect.
- Leakage: systems operating with suction pressure below the atmospheric pressure can have small leaks (close to seals etc.) allowing air to penetrate into the system.
- Inadequate evacuation before commissioning the refrigerating plant
- Decomposition of the refrigerant or the lubricating oil can occur due to catalytic action of the various metals in the installation and due to high discharge temperatures. Ammonia for instance decomposes into nitrogen and hydrogen.
How can the presence of non-condensables be proved?
Pressure gauges on refrigeration plants are always provided with a temperature scale parallel to the pressure scale and corresponding to the refrigerant used.
The condensate leaving the condenser has the saturation temperature corresponding to the condensing pressure. This temperature must be established by means of a thermometer. If the discharge pressure gauge shows a temperature higher than the measured temperature, this points to the presence of non-condensables.
The difference between the condensing pressure corresponding to the measured temperature and the total condensing pressure indicated by the pressure gauge is the partial pressure of the non-condensables.
The Grasso air purger is approx. 40 kg and 700 x 330 x 450 mm (L x W x H). It is factory-charged with the refrigerant R404A. Download our Grasso purger calculation program
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