Compressed air moisture separator filters are used to remove moisture and solid particles.
Moisture and solid particles pose a threat to the operation of pneumatic tools, control systems, and pneumatic valves, as they cause corrosion and damage to internal components. In addition, the presence of water, dust, or oil is unacceptable for certain manufacturing processes where compressed air comes into contact with raw materials, finished products, or chemicals.
Main Line Filters
Importance of Compressed Air Preparation
Compressed air preparation is a general term for the process of treating air compressed by a compressor. The treatment includes cooling, cleaning the air, and regulating pressure.
Cleaning includes the removal of oil particles, condensate, and other contaminants that may damage equipment and the production process.
Main line filters and separators play a significant role in air preparation after the compressor.
Overview of the Main Types of Main Line Air Filters
There are 3 main types of main line filters:
- Moisture separator filters are used to remove condensate, eliminate a significant amount of water and oil, and partially remove fine debris;
- Filters with filter elements effectively remove solid particles down to 0.01 µm;
- Activated carbon adsorption filters are used for very high-quality air purification to remove volatile compounds, minor oil residues, and moisture. Such purification is applied when air comes into contact with food products, for example.
Main Line Filters and Separators
Description and Operating Principle of Main Line Filters
Main line filters are equipped with a filter element.
Surface filters block harmful impurities by collecting them on their surface. Under the influence of gravity, impurity particles settle in the lower part of the filter and are removed through the condensate drain.
Description and Operating Principle of Separators
Moisture separators mainly use centrifugal force, droplet mass, and inertia to separate condensate and solid particles from the air.
Simply put, a moisture separator works similarly to a centrifuge — the air streams passing through it move in a circular path, and liquid particles are "knocked out" of the flow.
Applications of Main Line Filters and Separators
Compressed air filters and moisture separators complement each other and are widely used in many industrial pneumatic systems to clean air supplied by a compressor. Depending on the configuration, main line filters can be installed after mechanical and refrigerated dryers, receivers, and other equipment.
Filters-moisture separators of the SCC-MF-W series contain a large vane for spinning the air, a high-capacity bowl, and a filter element that retains solid particles. Thanks to this, the SCC-MF-W combines the qualities of an efficient moisture separator and provides a good filtration level.
This type of main line filter can be custom-manufactured for very large air flows — up to 330 m3/min. The Specialist online store offers standard production sizes up to 3.5 m3/min.
The filtration fineness depends on the installed replacement filter element — from 3 µm to 0.01 µm. The filter element kit includes replacement seals and silicone sealant. This provides additional tightness and eliminates air losses through the filter.
Main line filters of the SCC-MF series also combine the functions of a moisture separator and a filter, but compared to SCC-MF-W, they collect less condensate.
Condensate drainage in both series is performed manually. For automatic condensate discharge, they must be equipped with an SV-FD condensate drain valve or a similar device.
Advantages and Disadvantages of Main Line Filters and Separators
Main line air filters and separators are important elements of compressed air preparation systems. They are used to remove dirt particles, oil, and water.
Advantages of main line filters and separators:
- Increased equipment service life. Removing contaminants from the air prevents premature wear and equipment failures, reducing maintenance and replacement costs;
- Improved quality of technological processes and reduction of defective products. For example, when using a pneumatic spray gun, moisture or oil particles in the air may cause coating defects.
- Easy installation and replacement. Main line filters and separators have high flow capacity and are installed immediately after compressors and dryers, protecting a significant portion of pipelines and equipment from contaminants present in atmospheric air.
Disadvantages of main line filters and separators:
- Pressure drop. Installing any filters and separators reduces airflow velocity, especially the unjustified use of 0.01 µm fine filters and carbon filters;
- Not effective against microorganisms. Breathing air requires additional disinfection.
- The filter elements of main line filters are consumables that must be replaced depending on the degree of air contamination at the compressor installation site;
- For effective moisture removal, the air must be cooled using additional cooling devices because air after compression is significantly heated;
- Main line filters do not protect end equipment from impurities that may enter the air while passing through pipelines and valves — especially low-quality or outdated components that were installed and operated improperly. For example, rust particles from corrosion, wear debris, damaged seals, lubrication oil, and similar contaminants may enter the air.
Local Filter Moisture Separator
Description and Operating Principle of Moisture Separator Filters
Local purification filters are devices for removing moisture and solid particles, similar to main line filters. Compared to main line filters, they have a smaller nominal bore diameter and flow capacity because they are installed on individual branches directly before equipment to remove all possible contaminants that may have entered the device from the main line.
Filter elements of local filters are often made of homogeneous materials such as sintered bronze or polypropylene, but there are also structurally complex coalescing filters and activated carbon adsorption cartridges.
All filters for air preparation units can be classified as local filters. They are often integrated into a single housing with regulators, creating filter regulators.
Frequently Asked Questions
What is a main line separator in pneumatics?
A main line separator is a compressed air purification device that removes solid or liquid particles.
Where is a main line filter moisture separator installed?
Main line air purification filters are installed in the pipeline after the compressor and air cooler.
When is a main line filter needed for a compressor?
A main line filter is recommended if you need fine air filtration, excluding coarse filters that remove solid particles as small as 10 µm. It is also required when a large nominal bore and high flow capacity are needed.
How often should a moisture separator filter be replaced?
Moisture separator filters should be replaced after a decrease in their flow capacity, which indicates contamination of the filter material. Therefore, the service life depends on factors such as the filter type, environmental conditions, contamination of the supplied air, and others.
It is recommended to replace moisture separator filters at least once every 3-6 months or every 1000-2000 operating hours.
How often should a compressor air filter be replaced?
It is recommended to replace the filter every 3-6 months.
However, if the environment has elevated levels of dust, dirt, or contamination, the filter may need to be replaced more frequently to ensure efficient operation.
Why is a moisture separator needed on a compressor?
A moisture separator is a device used to remove moisture that is drawn in by air compressors together with air and condenses during cooling.
The presence of water in pipelines and internal parts of a pneumatic system leads to rapid failure of components and assemblies.
How do compressor filter moisture separators work?
The operating principle of filter moisture separators is similar to a centrifuge — compressed air is spun around an axis, and due to inertia, water droplets and solid particles move to the walls and settle at the bottom of the filter bowl.
What is the difference between a main line air filter and a local air filter?
Main line air filters are connected after the compressor, so they are designed for large air volumes with minimal pressure loss. The main line filter is often responsible for removing contaminants that entered the compressor and could damage pipelines and equipment.
Local air filters are installed in air preparation units. As a rule, this is done directly before a group of end-use pneumatic equipment on a branch separated from the main line. Therefore, local filters are designed for comparatively lower air consumption and must ensure air quality according to the requirements of specific equipment. Installing fine filtration filters and carbon filters before the equipment makes it possible to achieve the level of air purity required by certain devices without reducing air pressure in the main line.
