Why Should The Refrigeration System Be Vacuumed?

Let's first look at the composition of air. Nitrogen in air accounts for 78%, oxygen accounts for 21%, other gases account for 1%. So what effect do these gases have after entering the refrigeration system?

The influence of nitrogen

Nitrogen is a non-condensable gas. The so-called non-condensable gas means that the gas circulates with the refrigerant in the system, it does not condense with the refrigerant, and does not produce a refrigeration effect.

The existence of non-condensable gas has great harm to the refrigeration system, mainly manifested in the increase of the system's condensing pressure, the condensing temperature, the compressor discharge temperature, and the increase in power consumption. Nitrogen enters the evaporator and cannot evaporate with the refrigerant, it also occupies the heat exchange area of the evaporator, so that the refrigerant cannot be fully evaporated, and the cooling efficiency is reduced. At the same time, the excessively high exhaust temperature may cause the lubricating oil to be carbonized and affect lubrication effect, burn down the refrigeration compressor motor in severe cases.

The influence of oxygen

Oxygen and nitrogen are also non-condensable gases. We have already analyzed the hazards of non-condensable gases above. However, compared with nitrogen, if oxygen enters the refrigeration system, there are these hazards:

  • The oxygen in the air will chemically react with the refrigerating oil in the refrigeration system to produce organic matter, and finally form impurities, which enter the refrigeration system and cause bad consequences such as clogging.

  • Oxygen, refrigerant, water vapor, etc. are prone to chemical reactions that form acids, which will oxidize the refrigerating oil. These acids will damage the components of the refrigeration system and destroy the insulation layer of the motor. At the same time, these acid products will always stay in the refrigeration system, at first there is no problem, as time passes, it finally leads to the damage of the compressor.

The influence of other gases (water vapor)

Water vapor affects the normal operation of the refrigeration system. The solubility in Freon liquid is the smallest, and the solubility gradually decreases as the temperature decreases. The most intuitive impact of water vapor on the refrigeration system has the following three points

  • There is water in the refrigeration system. The first effect is the throttling structure. When the water vapor enters the throttling mechanism, the temperature drops rapidly and the water reaches the freezing point, resulting in ice formation and blocking the small holes of the throttling structure, resulting in an ice block failure.

  • Water vapor from corroded pipes enters the refrigeration system, and the water content increases, causing corrosion and blockage of the pipes and equipment.

  • Produce sludge deposits. In the process of compression, water vapor, together with refrigerating oil, refrigerant, organic matter, etc., produces a series of chemical reactions,  resulting in damage to motor windings, metal corrosion, and formation of sludge deposits.

In summary, in order to ensure the effect of the refrigeration equipment and prolong the life of the refrigeration equipment, it is necessary to ensure that there is no non-condensable gas in the refrigeration system, and the refrigeration system must be vacuumed.

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