The role and operation of the drier filter in modern refrigeration and air conditioning systems

The filter drier is a key component of any refrigeration and air conditioning system. The function of the filter drier is to ensure high efficiency of the cooling system and minimize system failure. Therefore, these filters should be used both in commercial systems and in industrial cooling installations.

The role of the filter drier in a refrigeration system

The main task of the filter is to ensure that the cooling system is dry and clean. Filter driers are responsible for retaining moisture and solid contaminants in cooling systems.

Various types of contamination that may appear in the refrigeration system pose a threat to parts that require high precision, such as compressors and expansion elements. Moisture can cause the formation of acids in the refrigeration system or deteriorate the lubricity of the oil, leading to compressor corrosion or seizure. In the case of the expansion element, the low temperatures occurring in it favor the freezing of the moisture, thus blocking the flow of the medium into the evaporator. As a consequence, the performance of the refrigeration system may drop.

Moisture and contamination can get into the refrigeration system as a result of loss of tightness during assembly, failure or servicing of refrigeration devices. Therefore, it is so important for many years of failure-free operation of the refrigeration system that the fitters and service technicians attach particular importance to ensuring the tightness of the installation, proper vacuuming before filling it with the refrigerant, using the filter drier and replacing it, so that the maintenance of refrigeration equipment does not involve any risk. air entering the serviced system.

Construction of the filter drier

Typical elements of filter driers are:

1. steel casing with a corrosion protection coating (Blue Refrigeration brand filter driers finished with epoxy powder coating)
2. inlet and outlet connections in various sizes:
   1. adapted to twisting, e.g. filter drier BLR/DML-032 (1/4 "SAE)
   2. solderable as for filter drier BLR/DML-165S (5/8 ”ODF)
   3. using a butt gasket, which can be found in the filter dehydrator brand Blue Refrigeration: BLR/DML-303FS (3/8 ”);
3. filter mesh capable of retaining (retaining) solid particles (in the case of the BLR/DML-084S (1/2 "ODF) filter, it is possible to filter contaminants with a size of 25 microns)
4. cartridge responsible for retaining moisture and impurities:
   1. made of 100% molecular sieves (a solution used by Blue Refrigeration in BLR/DML series filter dryers)
   2. using a molecular sieve and active alumina (as with Blue Refrigeration filters BLR/DCL series)
5. spring and perforated plate to maintain a fixed position of the elements inside the filter.

The refrigerant enters the filter through the inlet connection, then flows through the filter element and filter mesh, where moisture and impurities are trapped, accompanied by a drop in its pressure. It finally flows out of the filter through the perforated plate and outlet connection. Over time, due to the accumulation of moisture and/or dirt, the filter loses its drainage capacity. A clogged filter also causes an excessive drop in refrigerant pressure. It then needs to be replaced.

Selection of the filter drier - what to pay attention to

To properly select a filter drier that will keep your refrigeration system functioning properly and safely, you need to consider:

1. composition of the cartridge. A filter dryer with a cartridge containing, next to the molecular sieve, active alumina, will remove not only moisture, but also acids from the medium. This is because active alumina has a greater acid-retaining capacity than molecular sieves. On the other hand, it can retain additives used in oils used in cooling systems.

The choice of element composition affects the compatibility of the filter drier with the refrigerant and oil present in the system.

The use of a filter incompatible with the refrigerant or oil may result in the formation of acids, which pose a threat to the correct operation of the installation.

1. size and type of connections.
2. cooling capacity of the installation. The filter should be selected so that the flow through it does not cause an excessive pressure drop of the medium. Manufacturers quote cooling capacities that correspond to their stated pressure drop depending on the refrigerant. They also report the evaporation and condensation temperatures for which these capacities have been determined.
3. maximum pressure and operating temperature range of the filter.
4. refrigerant dewatering capacity. Manufacturers provide it depending on the temperature of the liquid refrigerant and its type. The catalogs also include information at what moisture content in the medium before and after the start of dehydration was determined.