Pre-Filters

Pre Filters

This page lists all 14 Pre Filters available from Metal Air Filters, manufactured by American Metal Filter Company (AMFCO). Products on this page are HI Series and HIA Series items, precision-engineered for demanding commercial, industrial, and HVAC applications.

AMFCO’s pre filters are built for long-term performance and reliability. Whether you need permanent washable replacements or specialty filtration products, all items on this page ship directly from our manufacturing facility with full specifications and compatibility documentation.

Commercial & Industrial Applications

Pre Filters from Metal Air Filters are deployed across a wide range of commercial, institutional, and industrial building types. The following applications represent the primary use cases for pre filters.

The HKA102025 20x25x1 washable aluminum foil mesh air filter delivers reliable performance across residential, commercial, and industrial HVAC environments where a durable, permanent, low-resistance washable aluminum foil mesh pre-filter is required for outdoor air intake, economizer filter, or make-up air intake filter applications. The impingement-type aluminum foil mesh construction, 200°F temperature rating, and all-aluminum corrosion resistance make this filter suitable for continuous operation in demanding outdoor and process applications that require frequent washing.

Outside and make-up air intake filter Systems

Commercial and industrial buildings’ outside air intake filter systems subject HVAC equipment to airborne particulate, rain entrainment, wind-driven debris, insects, leaves, and seasonal contamination that must be removed before air enters fan sections, heating and cooling coils, and downstream filter banks. The HKA102025 installed at outside air intake filter locations provides the first stage of particulate capture, protecting downstream equipment and extending the service life of higher-efficiency secondary filters. Its low resistance to airflow ensures that the washable aluminum foil mesh pre-filter does not degrade fan performance or restrict design airflow rates in systems where outside air flow is critical for ventilation compliance. Commercial office buildings, warehouses, manufacturing facilities, data centers, and institutional buildings with outside air systems benefit from the HKA102025’s combination of durable washable construction, 200°F temperature tolerance, and low pressure drop across the full 300–500 fpm operating range.

Rooftop economizer filter sections and hoods

Rooftop HVAC units with economizer filter sections and hoods use outside air for free cooling when outdoor conditions permit, continuously drawing in unfiltered outdoor air across the full operating season. The HKA102025 installed in rooftop economizer filter sections captures large particulate, airborne debris, and moisture that would otherwise reach economizer dampers, heat exchangers, and indoor air distribution components. The all-aluminum construction resists the UV exposure, thermal cycling, and moisture conditions characteristic of rooftop installations, maintaining structural integrity and dimensional accuracy across years of outdoor service. The simple warm-water washing maintenance procedure is particularly well-suited for rooftop applications where filter access is limited to scheduled maintenance visits, as the infrequent washing requirement and long service life between cleanings minimizes the number of rooftop access events required.

air handling unit filter sections — washable aluminum foil mesh pre-filter Applications

Commercial and industrial air handling units benefit from the HKA102025 as a permanent washable aluminum foil mesh pre-filter upstream of higher-efficiency secondary filter banks. By capturing large particulate, dirt, dust, and debris at the pre-filter stage, the HKA102025 extends the service life of more expensive downstream media filters and electrostatic filters, reducing replacement costs and maintenance frequency for the overall filter system. The low-resistance aluminum foil mesh construction minimizes the pressure drop contribution of the pre-filter stage, preserving fan capacity for downstream filter banks. Air handling units in commercial buildings, industrial process ventilation systems, clean room washable aluminum foil mesh pre-filter applications, and HVAC systems with multi-stage filter configurations are all well-served by the HKA102025’s combination of low resistance, durable washability, and broad temperature tolerance.

Coolant Mist and Industrial Ventilation

Light industrial manufacturing operations using coolant delivery systems, metalworking equipment, or process cooling generate oil mist and coolant aerosols that must be captured in ventilation exhaust streams. The HKA102025’s impingement-type aluminum foil mesh construction captures coolant mist droplets and oil aerosol through the same mechanism it uses for larger airborne particulate, collecting captured liquid in the frame corners where drain holes allow it to exit the filter during operation. Industrial ventilation engineers specifying mist control for machining centers, stamping operations, and process cooling exhaust applications select the HK Series washable aluminum foil mesh air filter for its 200°F temperature rating, all-aluminum construction compatible with common coolant chemistry, and heavy-duty washable aluminum foil mesh filter design that withstands the frequent cleaning demanded by industrial operating environments.

Frequently Asked Questions

How does the HKA102025 aluminum foil mesh air filter work?

The HKA102025 operates on the impingement principle: airborne particulate and coolant mist cannot follow the tortuous path through the 3-ply criss-cross aluminum foil mesh layers at rated 350 fpm velocity and collide with mesh surfaces where they are captured. The criss-cross assembly of corrugated foil mesh and expanded metal provides better average arrestance with low resistance to airflow.

How do I clean the HKA102025?

Rinse with a moderate-to-heavy stream of warm water from the clean side through to the dirty side until water runs clear. High-powered steam cleaning and chemical dips are unnecessary and not recommended. Air dry or shake off excess water before reinstalling. Filter Coat adhesive may optionally be reapplied after each wash if adhesive treatment is used.

Does the HKA102025 need to be installed in a specific orientation?

No — the HKA102025 may be installed vertically or horizontally in your HVAC system. No specific up/down orientation is required. The corner drain holes in three frame corners accommodate liquid drainage in multiple installation orientations.

What is the maximum operating temperature?

The HKA102025 HKA aluminum model is rated for 200°F continuous operation. This is lower than HFA (250°F), HMA (275°F), HMG (325°F), and HMS (900°F) series. Confirm your application does not exceed 200°F before selecting the HKA model.

What are the actual dimensions of the HKA102025?

Actual dimensions: 19.5″ H x 24.5″ W x 7/8″ D (±1/8″ H&W). Nominal size: 20x25x1. HK Series uses 1/2″ undercut on height and width — actual height = nominal H minus 1/2″, actual width = nominal W minus 1/2″.

Does the HKA102025 have a MERV rating?

No — the HKA102025 HK Series aluminum foil mesh filter does not carry a MERV rating. It is an economizer grade impingement-type filter for large particulate and coolant mist capture with low airflow resistance. For MERV-rated performance, consider the EC Series electrostatic filters (MERV 6) or the HF Series foam filters (MERV 4).

Can I use Filter Coat adhesive on this filter?

Yes — the HK Series may optionally be sprayed with Filter Coat, a water-soluble adhesive and detergent, before installation to enhance fine particulate capture. Filter Coat washes off during routine cleaning and must be reapplied after each wash cycle if desired. AMFCO does not sell Filter Coat nor any adhesive.

How often should I wash this filter?

The HKA is rated for “frequent and moderate” washing. Outside air intakes in dusty environments typically every 1–3 months; commercial pre-filter applications in moderate environments every 3–6 months; industrial coolant mist applications may need monthly washing. Inspect visually when the foil mesh face appears loaded with dust.

How does the HK Series compare to HF Series and HM Series?

HKA (HK Series): aluminum foil mesh, no MERV rating, 200°F max, 350 fpm rated — economizer grade pre-filter for outside air and low-resistance applications. HFA (HF Series): two-stage foam + aluminum mesh, MERV 4, 250°F max, 300 fpm rated. HMA (HM Series): aluminum screen wire mist eliminator, no MERV, 275°F max, 500 fpm rated — designed for moisture and mist separation. Each series serves distinct application requirements.

Is the HKA102025 compatible with my HVAC system?

The HKA102025 is designed for HVAC systems operating at 350 fpm rated airflow (300–500 fpm recommended range). It fits 20x25x1 nominal filter positions in outside air ducts, economizer hoods, and air handling unit filter banks. Verify your system operates within the 300–500 fpm range at the filter face for optimal performance.

Where are the drain holes on the HKA102025?

The HKA102025 has drain holes in three corners of the aluminum frame. These allow collected liquid (rain water, condensate, coolant mist) to exit the filter during operation. Ensure the drain holes are not blocked by the housing in the installed position, whether installed vertically or horizontally.