1) Refrigerated Air Dryer Filter Installation Layout
Compressed air systems equipped with refrigerated dryers generally require a three-stage filter. Dust particles in the compressed air can accumulate in the heat exchanger of a refrigerated dryer, causing scaling and impacting heat exchanger efficiency. A pre-filter should be installed after the oil-water separator and before the refrigerated dryer to remove most of the oil, water, and particles, ensuring the required conditions for the dryer and subsequent high-level filters. A main line and precision filter should be installed after the dryer to further remove water and oil to meet air quality standards. If necessary, an activated carbon filter should be installed after the precision filter.
2) Adsorption Dryer Filter Installation Layout
Oil and dust particles in compressed air significantly impact the service life and adsorption capacity of the adsorbent in an adsorption dryer. If dust particles from the air or piping enter the adsorbent, some of the dust may remain inside during regeneration and cannot be removed. This accumulation of dust will shorten the adsorbent's service life over time. On the other hand, after compressed air passes through an adsorption dryer, some adsorbent dust enters the air, leaving residual oil, water, and dust particles after the dryer. Therefore, compressed air filters of appropriate precision should be installed both before and after the air dryer. Furthermore, depending on air usage, activated carbon adsorption filters may be necessary.
3) Air-end Filters
The compressed air delivery pipeline and its accessories can contaminate air already filtered by high-precision air filters. Measurements show that a single stainless steel valve can generate several, dozens, or even more dust particles larger than 0.5μm when opening and closing. Therefore, to minimize the impact of compressed air delivery pipelines, in addition to considering pipeline material and maintenance, it is important to select filters of appropriate precision based on pipeline length, contamination levels, and the quality requirements of the air consumption point to ensure air quality.
For air that comes in direct contact with dry foods (such as cereals and milk powder), it is recommended to install precision filters to control particulate matter, water droplets, oil mist, and microorganisms. For odor removal requirements, an activated carbon filter is recommended. For other applications, a main line filter is sufficient. A pressure regulator is also required to adjust the required air pressure to meet demand and safety requirements. Lubricators are also required for air-consuming components such as cylinders and solenoid valves to ensure lubrication.
For non-condensable water, that is, meeting dew point standards, the selection of the refrigerated dryer or dryer is crucial. For general food contact or indirect food contact, a refrigerated dryer is sufficient. For compressed air that comes in direct contact with dried food (such as grains or milk powder) or has strict microbiological requirements, a refrigerated dryer or dryer with an outlet dew point of less than -40°C is required.