Air Dryer Maintenance is Key to Optimized Compressor Performance
In the process of compressing air, air compressors generate a lot of moisture. Compressed air that is too wet introduces rust and contaminants into the compressed air system, which can cause performance inefficiencies, low-quality air and equipment failure. Installing a compressed air dryer and performing simple air dryer maintenance ensures high performance from your air dryer and a moisture-free system.
The Importance of Using an Air Dryer for Compressors
Air compressors operate by ingesting ambient air and compressing that air into a smaller volume. This process generates water vapor because the moisture in the ambient air is concentrated as the air is compressed, causing the compressed air to become saturated. As the temperature drops after the compression process, the water vapor condenses into liquid condensation that may enter the compressed air system and lead to problems, including:
- Equipment Failure: Untreated moisture results in system-wide corrosion and rust. The resulting contamination may cause premature failure of air system components and connected equipment.
- Inefficient Equipment Performance: Rust, corrosion and contamination can cause blockages in the air distribution system that reduce the performance of air-powered equipment.
- Poor Quality Products: Moisture and associated contamination from the air compression system can be transferred to products as they are manufactured, degrading the quality of finished products.
Air dryers remove moisture and humidity from the compressed air, protecting compressed air system components, air-operated equipment and finished products from damage.
Compressed Air Dryer Types
To ensure efficient and effective performance, the air dryer must be properly maintained, but air dryer service requirements will vary depending on which type of air dryer you have.
Three Types of Air Compressor Air Dryers
- Refrigerated Dryers: The most common air dryer type, refrigerated air dryers are connected to the air compressor and cool the air using heat exchangers, a refrigerant circuit and compressor.
- Desiccant Dryers: This type of dryer features towers filled with desiccant material that attracts and removes water from the air.
- Membrane Dryers: Membrane air compressor dryers use selective permeation and a multiple-stage filtration system to separate moisture from compressed air.
Preventive Maintenance for Air Dryers
Each air dryer type has different preventive maintenance requirements, as follows:
General Preventive Maintenance for Refrigerated Air Dryers
Check filters: Regularly check pre-line filter elements and drains for blockages caused by dirt, dust, debris or other contaminants. Clogged filters or malfunctioning automatic drains reduce the effectiveness of the air dryer. Replace clogged filter elements and defective automatic drains.
Check for refrigerant leaks: Check the suction pressure gauge or readout to make sure it’s within normal operating range.
Drain operation: Ensure the dryer’s automatic drain is working so collected condensate can be removed from the system. Address any malfunctioning valves or drains. If there is a stainer to trap contaminants, it should be opened and cleaned when needed.
Check air dryer chiller temperature: This can be done easily if the air dryer has a digital readout or indicator. If the indicator shows a fault designation, there is likely a problem that requires air dryer service by a professional technician as it can indicate a problem with the refrigeration circuit.
General Desiccant Air Dryer Preventive Maintenance
Sample the desiccant: There are typically ports on the tower that are used for replacing desiccant but can also be used to sample the desiccant. Ensure that the desiccant beads are of the correct size and color. Discoloration indicates oil contamination, which will reduce efficiency of the desiccant. Size reduction indicates that the desiccant is worn down. In either case, the desiccant should be replaced.
Check the dust filter: Desiccant air dryers use a filter to capture desiccant dust. The filter should be checked for pressure drop. Significant pressure drop indicates that the filter cartridge should be changed. If there is no way to check the pressure, change the filter on a regular schedule.
Check prefilters: Check pre-line filters for blockages caused by contaminants as clogged filters will reduce the efficiency and effectiveness of a membrane air dryer.
Check drain operation: Ensure that drains are working properly so that liquid moisture can be effectively removed from the system before it reaches the dryer. Address malfunctioning drains.
General Membrane Air Dryer Preventive Maintenance
Check prefilters: Check pre-line filters for blockages caused by contaminants as clogged filters will reduce the efficiency and effectiveness of a membrane air dryer.
Check drain operation: Ensure that drains are working properly so that liquid moisture can be effectively removed from the system before it reaches the dryer. Address malfunctioning drains.
Check for oil contamination: If the membrane dryer becomes contaminated with oil, the membrane cartridge will need to be replaced.
Troubleshooting Air Dryer Issues
System moisture is an indicator of air dryer malfunctions. Here’s how to troubleshoot moisture issues.
Insufficient drying
If your air dryer is losing effectiveness:
- In all dryers, inspect filters. Clean or replace blocked or dirty filters to restore dryer performance and efficiency.
- In a refrigerated air dryer, ensure heat exchanger coils are clean.
- Refrigerant leaks in a refrigerated air dryer can impair the cooling process, making the dryer less effective. Fix leaks and restore the refrigerant.
- In desiccant dryers, check the desiccant as it may be contaminated or saturated. If so, replace the desiccant.
Water in compressed air
If there is liquid water in your compressed air:
- Inspect automatic drains for malfunctions or blockages. Clear blockages or repair the drain.
- Ensure your dryer is properly sized. An undersized dryer will not effectively manage the moisture load.
- Monitor ambient temperature. Standard maximum is 100 degrees F. You may need an air cooler or a more robust dryer if high temperatures or humidity are issues in your area.
- Monitor the compressed air inlet temperature to the dryer, standard maximum is 100 degrees F. Anything over that significantly reduces dryer capacity. If the inlet temperature is over 100 degrees the compressor aftercooler may need service and/or the compressor room ventilation system may need to be addressed.
Air Dryer Component Lifespan
When properly maintained, you can expect a long operational life from your air dryer. Here are some general guidelines so you know what to expect.
Refrigerated air dryers: With proper maintenance, refrigerated air dryers usually last 8 to 10 years. In a leak-free system, the refrigerant should last the lifetime. Air filter elements and automatic drains will need cleaning or replacement on a regular basis.
Desiccant dryers: A desiccant dryer should provide 8 to 10 years of service. Desiccant beads will need replacement every 3 to 5 years, depending on the contamination and moisture load of the application. Air filter elements and automatic drains will need cleaning or replacement on a regular basis. Dew point monitors require regular recalibration (if equipped).
Membrane dryers: Membrane dryers have a long lifespan of about 10 to 15 years. The inlet filter elements must be changed and automatic drains replaced as needed.
Don’t let moisture damage your equipment or degrade your air quality. Contact JHFOSTER, your air compression partner. We can evaluate your system to ensure that you have the right type and size air dryer and we provide expert support and service for your air system and its components.
