Pneumatic braking systems require a large quantity of clean, dry compressed air per minute to operate correctly. The installation of an air dryer is essential to maintain decontaminated air in the system.
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The filter drier, protector of the air conditioning circuit
23.05.2023
What is the role of a filter drier in an air conditioning system? To answer this question, it is necessary to know how your air conditioning works.
Understanding the air conditioning system
Your vehicle's air conditioning system is a closed loop. During a cycle, the refrigerant, also called "coolant", changes from a gas to a liquid. It then cools the air before it is released into your cabin.
- 1. The compressor: How does the refrigerant circulate in your air conditioning system? Thanks to the compressor. The compressor creates a pressure difference, i.e. it sucks in the low-pressure refrigerant gas, compresses it, and then pumps it back into the system. The gas is now under high pressure and hot.
- 2. The condenser: The hot gas flows into the condenser. Equipped with a fan, this component cools the refrigerant. This drop in temperature causes the gas to liquefy completely.
- 3. The filter drier: The refrigerant, now liquid and warm, enters the filter drier (also called "filter drier" or "desiccant bottle"). Strategically positioned on the circuit, this element protects the other components by eliminating humidity, but also acid and solid particles from the fluid.
- 4. The expansion valve: Purified, the refrigerant reaches the expansion valve. As it passes through this component, the fluid "expands", i.e. its pressure drops, then its temperature drops drastically, leading to its partial evaporation.
- 5. The evaporator: In the evaporator, the refrigerant completely changes state. By absorbing the heat contained in the outside air, the refrigerant gradually boils until it becomes completely gaseous. During this boiling process, the temperature of the fluid remains stable at a low temperature, thus cooling the air passing through the evaporator. Once cooled, the air flow continues to the cabin. The refrigerant gas is drawn back to the compressor where a new cycle can begin.
“💡 Water dripping under your vehicle when the air conditioning is on? This is normal! When the warm air flow, loaded with moisture, passes through the cold evaporator, a thermal shock occurs. This temperature variation creates condensation and water droplets appear. These droplets end up flowing under your vehicle.“
The HIFI FILTER® range of filter driers
The filter drier against contaminants
As mentioned earlier, these desiccant bottles remove water, acid and particles from the refrigerant. But what are the dangers of these contaminants? And how does this filter combat them?
- Moisture: Leaks in the system or improper handling during maintenance allow moisture to enter your air conditioner. Water can cause corrosion of metal components, degradation of lubricants and the formation of frost. With the desiccant bottle, water is absorbed by a desiccant material, usually silica gel (also called silica gel) in the form of a ball.
- Acid: Its appearance is due to excess humidity. A corrosive element, it prematurely wears out the components of the air conditioning system. This pollutant is captured in the desiccant filter thanks to the alumina oxide, also in the form of a ball.
- Solid particles: They can come from the manufacturing residues of the circuit, from the normal wear and tear of the system components and from the outside air in case of a leak. An excess of these contaminants clogs the components, degrades them, reduces their performance, and even causes the air conditioning system to stop working. In the dehumidifier, these contaminants are retained by a screen and/or a filtering media.
In addition to retaining these contaminants, the filter drier is also a refrigerant reservoir. The objective? To compensate for variations in refrigerant volume in the circuit. In concrete terms, this reservoir can temporarily store the excess liquid or, conversely, reinject it in order to maintain an adequate level in the circuit.
The importance of regular maintenance
It is important to regularly maintain your air conditioning filter drier to :
- ✔️ Reduce the risk of breakdowns: The desiccant bottle removes water, acid and particles from the air conditioning system before they can cause serious damage or even a complete shutdown.
- ✔️ Extend the life of the air conditioning system: The better the filtration of the fluid, the more the system components are protected and the longer their life. To maintain this performance, it is essential to change the filter drier regularly.
- ✔️Improve cabin air quality: The filter drier keeps the air conditioning system in good condition, ensures optimal operation of the components and finally, guarantees healthy and fresh air in your cabin.
When to replace a filter drier?
In general, manufacturers recommend replacing your desiccant bottle every 3 years. Nevertheless, the life of a desiccant is more or less long depending on the type of air conditioning system, the conditions of use and the quality of maintenance.
“⚠️Every time the air conditioning system is opened, you need to change your filter drier. Why? This filter is made of an extremely hygroscopic desiccant, which means that it attracts humidity from the air. If the circuit is open, the material will capture the humidity of the ambient air, the drier will be quickly saturated and once the circuit is closed, it will no longer fulfill its role. Also, if the system is opened, dust can contaminate the filter and reduce its efficiency.“
Who can change a filter drier?
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