Refrigeration system to produce non-condensable gas reasons?

1, charging refrigerant before the refrigeration system evacuation is insufficient
Before charging the refrigerant, the refrigeration system within the compressor cylinder, condenser, evaporator, and the system of piping have been full of air, in order to exclude these air before charging the refrigerant, the need for refrigeration system vacuum, sometimes due to subjective and objective reasons, the refrigeration system is not sufficient to vacuum, not up to the requirements of the system, there is a small amount of air in the system.
2, Charging refrigerant with
Refrigeration system in the refrigeration system before charging refrigerant, charging the tube used in full of air, due to man-made reasons, such as charging refrigerant, no exhaust despite the air inside the sub, directly connected to the refrigeration system, these air with the charge 1 refrigerant into the refrigeration system.
3, in the refrigeration system maintenance mixed with non-condensable gases
Refrigeration system work for a long time, it is inevitable that need to check and repair or cleaning and replacement, so that sometimes need to dismantle the machinery or piping air is often in the process of dismantling and installation of this process into the refrigeration system, the internal.
4, from the outside atmosphere into the internal system
In some refrigeration systems, if the working pressure is lower than atmospheric pressure, the atmospheric air will penetrate into the refrigeration system through a variety of gaps. These gaps are distributed in various types of valves, compressors, non-welded and many other places.
5, from the chemical reaction of the refrigerant
In the ammonia refrigeration system, the refrigerant ammonia at a certain temperature and pressure can be decomposed into ammonia and hydrogen and its decomposition degree and temperature 1 degree and pressure into a positive relationship, the higher the temperature and pressure, the greater the ammonia decomposition. In the Freon refrigeration system, Freon may be mixed into the system with impurities in the chemical reaction, resulting in non-condensable gases. For example, R12 reacts with water under certain conditions to produce carbon dioxide.