3 Types of Filters


There are many types of filters available to provide filtering for various kinds of materials and equipment. All share the same purpose: to sift out or eliminate undesirable elements from a system. Here are three types of filters.

1Absorptive Filters

An absorptive filter is specifically meant to siphon out excess or dangerous energy waves, such as x-rays or sound waves. These filters aren’t meant to separate out any kinds of physical matter or particulates. Instead, they absorb out-of-band signals to eliminate the risk of high-power or high-frequency waves. They allow acceptable, or in-band, types or levels of energy to pass through without interruption. Keep in mind, absorptive filters do not reflect any of the waves they’re filtering, although there are filters that do reflect rather than absorb waves.

2Water Filters

A water filter is likely the most commonly used by the average consumer. They can be built into refrigerators, purchased for use in water pitchers, attached to taps or purchased as on-the-go tools for outdoor activities, commonly in the form of straws. Water filters are also commonly employed in various industries, such as waste management. Because water can contain both physical and chemical contaminants, the type of filtrate utilized will vary based on need. Because tap water is already professionally filtered, a household water filter will typically use physical filtration, with porous particles or weaves meant to trap physical contaminants. Water treatment plants, on the other hand, will generally use a combination of physical and chemical filters to purify the water as much as possible for future consumption.

3HVAC filters

Filters for HVAC, or heating, ventilation and air-conditioning, systems are also commonly encountered in people’s everyday lives. HVAC filters are essential to the air filtration of homes with central air that combines all these elements, rather than separate systems for each element. These are also physical filters that work similarly to water filters. They’re meant to trap physical contaminants circulating in the air of a home, such as mold spores and airborne dirt particles. HVAC filters need to be inspected and replaced regularly. They can fill up with debris over time, which will hamper their ability to filter, and if they become damp they may become sources of mold and mildew growth.

You may not encounter all types of filters in your daily or professional life. You’re much more likely to knowingly use a water filter than an absorptive filter, for example, unless you work in an industry where absorptive filters are utilized.