Which Refrigerants Are Added To The Gas State, And Which Refrigerants Must Be Added With Liquid?

- Jun 28, 2019-

Which refrigerants are added to the gas state, and which refrigerants must be added with liquid?

First, the charging principle: 

1, liquid charging

Filling the liquid refrigerant is to put the refrigerant cylinder upside down, because the inside of the cylinder is a liquid refrigerant. After the cylinder is inverted, the liquid refrigerant enters the refrigeration system through the liquid addition tube. Note: The fluorine release port of some cylinders will reach the bottom of the cylinder. At this time, although the cylinder is upright, it is still liquid refrigerant.


2. Gaseous charging

Filled with gaseous refrigerant, the refrigerant cylinder is standing upright; since the upper space of the cylinder is already a gaseous refrigerant, the refrigerant added to the refrigeration system at this time is the gaseous refrigerant.


Second, why should we add gas and liquid, why do some refrigerants need to add gas, and some have to add liquid?


1, three concepts


Single refrigerant, non-azeotropic refrigerant and azeotropic refrigerant


Single-component refrigerant: The refrigerant component has only one working fluid; for example: R22, R290; non-azeotropic refrigerant: a refrigerant obtained by mixing two or more different refrigerants in a certain ratio, which is saturated under gas. The composition of the two phases of the liquid is different; for example: R404A, R410A;


Azeotropic refrigerant: An azeotropic mixture of two or more different refrigerants mixed in a certain ratio. Such a refrigerant can maintain a certain evaporation temperature under a certain pressure, and the gas-liquid two phases always maintain the composition ratio. For example: R500, R508A;


2, liquid or gaseous?

1), single-component refrigerant, whether it is gaseous or liquid, the composition inside will not change, so when filling the refrigerant, it can be filled with gas.

2) Although the azeotropic refrigerant has different compositions, since the boiling points are the same, the components of the gas and liquid are also the same, so that the gas can be filled;

3), non-azeotropic refrigerants have different boiling points, so the liquid refrigerant and the gaseous refrigerant are actually different in composition. If the gas is added, it will inevitably lead to different refrigerant components, such as only added. A certain gaseous refrigerant, so only liquid can be added.


Third, how to distinguish between single working, azeotropic, non-azeotropic?

Single-component, azeotropic refrigerants can be filled with gaseous; non-azeotropic refrigerants must be filled with liquid; but how do we distinguish between azeotropic and non-azeotropic refrigerants? Look at the refrigerant model; according to the refrigerant naming rules:


Azeotropic refrigerant: The first digit after R is "5", and the two digits at the back are numbered in practical order. Such as: R500, R501, R502... R507


Non-azeotropic refrigerant: The numbering sequence of No. 400 behind R, in order. Such as: R400, R401, R402, ... R411


4. Why does the non-azeotropic refrigerant have to be added with liquid, why should the non-azeotropic refrigerant be added with liquid?


Let's take a look at the R410A refrigerant. Obviously, the refrigerant at the beginning of "4" is definitely a non-azeotropic refrigerant with the following composition: R32 (difluoromethane): 50%; R125 (pentafluoroethane): 50% ;


Check the refrigerant physical property table to see that R32 and R125 have different boiling points, which is why it is called non-azeotropic refrigerant. When R410A refrigerant cylinder is left, R32 and R125 will not cause the same boiling point, which will inevitably lead to refrigerant cylinder. The upper part of the vaporized refrigerant has evaporated, the composition is not 50% R32 + 50% R125. Since the boiling point of R32 is low, it is likely that the upper part of the refrigerant is a component of R32. If the refrigerant is added, the refrigerant added is not R410A, but R32. Other non-azeotropic refrigerants can only be added with liquids for the same reason.