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Permatron Model IN® Filter - 1" or 2" Thick - Washable Electrostatic

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Model IN® Washable Electrostatic Air Filters

All filters undersized by 1/2" on the length and width as is standard for filter sizing, please measure your current filter.

From the paper mills on the West coast, to textile mills on the East coast, and to the hospitals and airports in the Midwest, Permatron’s commercial air filters are the original industrial workhorses of permanent, washable electrostatic air filtration, proven effective for over 60 years. Model IN is one of the best and the oldest washable electrostatic air filters available today, ideal for applications that require durability because high velocity air flow is pushed through limited filter surface areas or high dirt load filtration with easy cleanability.

Model IN will outperform and outlast a metal mesh panel filter in many applications because of its durability and easy cleanability. Model IN with a stainless steel frame works well in wet, marine environments where mold and bacteria can be a concern.


The Model IN is best for industrial applications where potential dirt load is high and where low resistance and cleanability are critical. Durable construction allows high velocity air to be pushed through limited filtering surface areas, often found in older HVAC systems. This environmentally friendly air filter contains multiple layers of our custom woven electrostatic polypropylene media, with expanded wire support both front and back.


Model IN (1” & 2”) features our exclusive Accumulator Chamber®. Using a unitized filter bank design, multiple sets of steel framed media is assembled with distinct separation to create a triple action filtration system. This prefilter/afterfilter assembly promotes free air flow with superior dust holding capacity while resisting face loading. Excess particulates sweep through the prefilter and cross currents within the chamber cause further agglomeration and settlement until the filter is rinsed clean. Outer steel frame contains strategically placed drain holes for thorough cleaning. 

Accumulator Chamber

• Stainless steel frame
• Average Arrestance Efficiency: 78%
Dust Holding Capacity: 130 gm.
• Initial Air Flow Resistance: 0.11” w.g.
• U/L Classified as to Flammability Only
• 5 Year Manufacturer Warranty

• Available in 1/2", 1", or 2" thick

A note about washable filter frame thickness:

A thicker frame on a washable filter does not contain more media nor is the media doubled up, pleated, or thicker in any way. The advertised efficiency and air flow remains the same throughout all thicknesses of washable filters in each of their respective LxW dimensions. In filtration, efficiency is the particle size a filter will capture. The frames are available in many sizes to allow users to install the filter into varying widths of tracks, slots, grilles, etc. This eliminates the need for modification of the track/slot/grille/etc. when switching from one type of filter to another, i.e. switching from a 2" thick pleated filter to a washable filter. All washable filters should be washed monthly or as needed; so they are made with enough media to work as designed and allow for proper dust holding capacity until the monthly/as needed wash is required.