Air filters are one of the most vital components in a compressed air system. In addition to removing debris and contaminants, the compressor air filter helps the unit operate more efficiently and minimizes the impact of wear and tear over time.
Air in-take filters are important, as they keep out the dust that causes wear to the compressor element, valve, and other essential components. Besides wear, the properly-sized filter reduces inlet pressure drop that causes a reduced compressor flow and higher operating temperatures. Air filters are provided on air compressor intakes to prevent atmospheric dust from entering the compressor and causing scoring and excessive wear.
Size: A filter for an air compressor is rated based on inlet flow, which is typically measured in cubic feet per minute (cfm). Choosing a filter with a cfm that is twice the compressor’s cfm flow rate will lower the filter’s pressure drop, which reduces energy consumption and extends element life.
Extraction efficiency: Extraction efficiency refers to the filter’s ability to remove dust from the air. A filter with a 99.9% rating will remove twice the amount of dust as a filter with a 99.8% rating.
There are two types of air filters: the dry type and the oil-wetted type. Generally, dry type filters are more efficient than oil-wetted types in trapping and removing very fine, solid particles from the incoming air. However, dry-type filters must be cleaned and replaced more often than oil-wetted types.
Oil-wetted types are often used where there is heavy dust concentrations present in the atmosphere. Dry filters employ many different materials for the filter media. Paper, polyester felt, and fine wire mesh are a few examples. The filter media can be folded, wrapped, and layered in many configurations to achieve the desired efficiency. Although the dry filter is more efficient than the wetted-type filter, the pores in the dry filter media become clogged and result in a pressure drop across the filter. Dry-type filters cannot be used successfully where intake air contains moisture or vapors in amounts that would cause disintegration of the filtering media. The main advantages of the dry-type filter, when used in an approved application, is its high efficiency and ease of maintenance.
Wet filters have filter elements that are coated with a film of oil. The oil film catches airborne particulates before they reach the actual filter element media. Wetted type filters are of two designs, oil-wetted and oil-bath filters. In an oil-wetted filter, a coating of oil is deposited on the filter element, which is usually made of layers of wire mesh. The oil coating is intended to adhere to the element for a fairly long service period. The airborne particulates are impinged or trapped on the filter element which has been covered with a film of oil. In an oil-bath filter, the same viscous impingement principle is employed. However, the airflow is directed through the oil sump, carrying oil with it to the filter element where the oil collects and washes the impinged particles down to the oil sump, forming sludge. The self-washing aspect of the oil-bath filter extends the time between maintenance routines.
Inspections: Air filter inspections are to be performed when any of the following conditions exist: (a) Prescribed time interval on the maintenance schedule has elapsed (b) Pressure drop across the filter element indicates a maintenance requirement (c) One-fourth inch of sludge has built up in the oil sump of the oil-bath type filter.
Maintenance: Maintenance methods differ for each type of air filter. Use the appropriate method for the filter undergoing maintenance per the following paragraphs. Dry-type filter elements can easily be damaged allowing harmful particulates to pass. If in doubt about correct cleaning procedures, replace the filter element.
TESCORP has both the inventory and expertise to help you size and maintain your air filters in order to achieve the best efficiency and longevity for your compressor systems. Learn more HERE or reach us at sales@tescorp.com.