The appropriate selection and design of a compressed air filtration system is very important for achieving optimal air quality. The design will significantly affects the efficiency and longevity of your filters and the filter efficiency.
In other words, you need to put the compressed air filters and dryers in the right order, in order for them to function optimally and for you to have the highest quality compressed air.
Let's explore the recommended sequence of compressed air filters, the integration of compressed air dryers, and the rationale behind this specific setup.
Filters Needed in Compressed Air Systems
Compressed air filters are essential to remove contaminants such as particulates, moisture, and oil vapors, which can damage tools and degrade product quality. The selection of filters depends on the required purity class as per ISO 8573-1 standards. The types of filters typically used include:
Particulate Filters: These filters remove solid particles from compressed air. The selection of particle size to be filtered should align with the sensitivity of your equipment to particulates.
Coalescing Filters: Effective for removing oil and finer particulates, these filters are crucial in applications where oil vapors and fine oil mists could pose problems.
Activated Carbon Filters: These are used for removing odors and vapor phase hydrocarbons, particularly in applications requiring odor-free air, such as food processing or pharmaceuticals.
For detailed information about the different contaminants in compressed air, click the link. I also have a page about compressed air filters in general.
Selecting the right compressed air filter is the first step in reaching our goal of , refer to our dedicated article on compressed air filters.
Other Equipment Needed
When setting up a system to clean compressed air, it's not just about the filters. You also need some other pieces of equipment like air receivers, water separators, and air dryers to keep everything running smoothly.
Air Receivers act like a buffer for your system. They hold compressed air and help keep the pressure steady, but they also help trap some of the water that comes out of the air as it cools down.
Water Separators pull out most of the water and oil that's mixed in with the air. This stops a lot of gunk from moving further along into your system. It's a "bulk remover" of liquid water.
Compressed Air Dryers take care of the moisture that the water separators can't catch. They really dry out the air, which keeps water from condensing down the line. This is very important because too much moisture can freeze up lines in the winter and cause rust or other damage that'll cost you time and money.
By using all these pieces together—receivers, separators, and dryers along with your filters—you're setting up a system that's more reliable, uses less energy and delivers cleaner compressed air.
Required Sequence of Filters and Equipment
The arrangement of filters in a compressed air system should follow this sequence:
- Air Compressor
- Water Separator
- Wet Receiver
- Coalescing Filters
- Compressed Air Dryers
- Particulate and Activated Carbon Filters
- Dry Receiver
Let's take a look at each one of them:
Water Separator
Positioned right after the air compressor, water separators are crucial for removing bulk liquids such as water and oil from the compressed air. This step prevents excessive contamination before the air enters dryers or coalescing filters, enhancing their efficiency and lifespan.
Air Receivers
Air receivers, also known as air storage tanks, come in two types: wet receivers and dry receivers.
Wet Receivers are installed right after the air compressor. By slowing down the airflow and cooling the air, wet receivers help condensation and help remove a significant amount of water from the air. It's very important to have an automatic condensate drain with wet receivers.
Dry Receivers are positioned after the air has passed through dryers, and usually all filters, storing air that has been dried and cleaned. Dry receivers help in stabilizing the pressure and air supply from the dryer.
While smaller and medium setups typically only use one type of receiver, larger systems often employ both to maximize efficiency and air quality control. Using both types isn't always necessary, but it can enhance the system's capability to handle moisture and maintain steady air flow in more demanding environments.
Coalescing Filters
These filters are essential for removing finer oil and water aerosols, as well as atmospheric particulates, microorganisms, and residues from the system piping like rust flakes or mineral scale. Coalescing filters remove both liquids and dust particles.
Compressed Air Dryer
Compressed air dryers reduce water vapor levels in the air stream, preventing condensation downstream when the air cools. The type of dryer used (e.g., refrigerated, desiccant) depends on the required dew point for the application.
Dry Particulate Filter
Positioned at the final stage, these filters remove the finest particulates from the air stream, with filtration capabilities down to 0.01 microns. They are typically used with adsorption type dryers, which ensure that the air is sufficiently dry to prevent clogging and maintain the efficiency of these fine filters.
Activated Carbon Absorption Filter
These filters are used for removing odors and oil vapors from the air stream, which is especially important for applications requiring odor-free and extremely clean air. Activated carbon filters are placed as the last step to make sure that the air is as dry as possible and contains the least amount of other contaminants (particles, dust). This maximizes the filter’s effectiveness.
It is often required to place a fine particulate filter after the activated carbon filter, as it can release tiny carbon fines (dust).