The Importance Of Filter-drier In An Air Conditioner

An air conditioner is made of many parts. The filter drier is one of them. Although most users do not realize the importance of a filter drier or is hardly aware of its presence, it plays a pivotal role in the functioning of an air conditioner. This filter drier is present right at the heart of the system. It is cylindrical in shape and contains a desiccant and filter. An air conditioner is a mechanical system. Permeation of moisture in the system can bring down its efficiency and cause premature failure. The job of filter-drier is to filter out unwanted particles and remove and hold moisture to prevent it from circulating through the system.

An air conditioner has a compressor, condenser, metering device, evaporator, copper lines, oil, and refrigerant. The components are made of various metals such as the iron, copper, steel, aluminium, brass etc. When assembling the components together, a series of chemicals are applied such as Flux, Epoxy glues. It is quite natural for air to get into the system during the installation. The hydrogen nitrogen or oxygen can react with chemicals and metals under high temperature and pressure which are often pervasive in the unit to form hydrochloric and hydrofluoric acids. These acids eat up metals and other materials of construction often leaving the unit beyond repair. The motor is vulnerable to the acids. The insulation of the motor winding is completely damaged. The motor starts burning out. The burning produces smouldering products that are pumped by the compressor into the entire loop. As result the liquid refrigerant and lubricating oil also gets contaminated.

It is here that filter-drier comes to play a vital role. The desiccant present in the filter-drier absorbs the moisture that prevents it from affecting the refrigerant and the lubricating oil. The filter of the system sieves the debris. Here are three top functions of filter drier-

• The filter traps debris that may be inside the A/C system.

• The desiccant present in the cylindrical part absorbs moisture that may have entered inside the A/C system.

• The filter also acts as a temporary storage container for oil and refrigerant when they are not being used.

When the compressor of an air conditioner is serviced or replaced it is always wise to change the filter-drier as well. Many compressor warranties also need it. This is because the desiccant also has a particular capacity beyond which it cannot absorb any more moisture. So when a burnt compressor is serviced a lot of moisture and debris can get inside the system. The filter-drier which also gets exposed to the atmosphere at this time may not be able to soak all the moisture. It is better to fit a new one in the system. Moreover the filter gets clogged with debris from time to time which restricts the flow of refrigerant.

You should also know the function of an accumulator in this context. An accumulator is used in systems that have an orifice tube instead of an expansion valve. An expansion valve controls the entry of refrigerant into the evaporator. An orifice tube also does the same thing. It has a very small opening through which liquid refrigerant passes. It is a fixed device with no moving parts. Unlike an expansion valve, it cannot vary the amount of refrigerant flowing into the evaporator. In case of orifice tubes there are always chances of more refrigerant flowing into the evaporator. An accumulator’s primary function is to store liquid refrigerant that is exiting the evaporator, to prevent it from reaching the compressor. Entry of liquid refrigerant into the compressor can damage it. An accumulator is considerably larger than a filter/drier. It is located near the evaporator outlet, in the low-pressure section of the system.

Filter dryers are of two types -

Liquid Line Type:
Ths is situated before the expansion valve just after the condenser coils. It filters the liquid refrigerant that goes towards the evaporator valve from the condenser. With fine filters, these can remove 20 micron or above from the system. Modern versions of these parts have sight glasses that enable you see the level of refrigerant. Some have chemicals that can detect level of moisture based on color of the fluid.

Suction Line Type: is placed after the evaporator and before the compressor. These are meant for clean-up and are installed in a system suction line.


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