18x25x1 Nominal Air Filter Pad Holding Frame

Description

18x25x1 Media Pad Filter Pad filter pad holding frame – HPG101825

The HPG Series 18x25x1 media pad filter pad filter pad holding frame is designed to replace disposable air filters in residential, commercial and industrial HVAC air air filter frame applications with an economical, replaceable filter pad holding system. This industrial-grade filter pad holding frame provides a permanent, reusable framework that accepts standard 1-inch thick filter pad media pads, delivering decades of reliable service while dramatically reducing long-term filtration costs compared to disposable filter alternatives.

Engineered with heavy-duty 24 gauge galvanized steel air filter frame construction, the HPG101825 combines exceptional structural integrity with corrosion-resistant durability for demanding HVAC air filter frame applications. The permanently welded face grid provides uniform media support across the entire 18×25 inch surface area, ensuring optimal airflow distribution and preventing media bypass or sagging under differential pressure conditions. This robust construction maintains dimensional stability throughout extended service cycles, delivering consistent filtration performance in both indoor and outdoor installations.

Product Specifications

Specification	Value
Nominal Size	18x25x1
Actual Dimensions	17.5″ H x 24.5″ W x 0.875″ D
Frame Material	24 gauge galvanized steel
Face Grid	30 gauge galvanized expanded metal
Max Operating Temperature	325°F (163°C)
Weight (Frame Only)	2.8 lbs
Carton Pack	12 units per carton, 33.6 lbs total
Classification	UL Classified 900
Product ID	1778
UPC	840373525485
GTIN	00840373525485
Manufacturer	American Metal Filter Company
Country of Origin	Made in USA
Service Life	5-10 years (frame only)

Product Highlights

• Rigid, Versatile Frame: Heavy-duty 24 gauge galvanized steel construction provides exceptional strength and maintains dimensional stability throughout decades of service
• Optional Wire Gate: Hinged wire gate available when specified during ordering for convenient filter media access without frame removal
• Decrease Per-Filter Replacement Costs: Replace only the filter media instead of the entire filter assembly, reducing long-term filtration costs by 60-80%
• Corner Drain Holes: Integrated drainage holes in all four corners allow water evacuation when washing or in high-humidity applications
• UL Classified 900: Third-party certification for use in commercial and light industrial HVAC applications up to 325°F
• Permanently Welded Face Grid: 30 gauge galvanized expanded metal grid provides uniform media support without the risk of grid detachment
• Corrosion-Resistant: Hot-dip galvanized coating protects against rust and corrosion in harsh environments
• Made in USA: Manufactured domestically with stringent quality control and compliance with American manufacturing standards

Construction Details

The HPG Series uses a galvanized galvanized steel air filter frame to enclose a metal support grid. The grid is made of expanded metal and is permanently attached to the inside flange on the air exit side. It fits firmly inside the filter pad holding frame giving the HPG Series exceptional strength and durability. As an option, a hinged wire gate may be installed on the air entrance side of the filter pad holding frame when specified during ordering. The filter pad holding frame is made with mitered corners and is secured with pop-rivet(s) for permanent assembly that withstands repeated handling and media replacement cycles.

The 24 gauge galvanized galvanized steel air filter frame provides the structural backbone of the HPG101825, offering superior rigidity compared to lighter gauge alternatives while maintaining reasonable weight for handling. the filter pad holding frame’s mitered corner construction ensures precise 90-degree angles that fit properly in standard filter housings without binding or air bypass gaps. Each corner joint is secured with industrial pop-rivets that create a permanent mechanical bond, eliminating the risk of corner separation that can occur with lesser quality construction methods.

The 30 gauge galvanized expanded metal face grid is permanently spot-welded to the filter pad holding frame’s interior flange on the air exit side. This expanded metal construction provides optimal characteristics for filter media support – it offers high open area percentage for minimal airflow restriction while providing sufficient surface contact to prevent media sagging or tearing under differential pressure loads. The grid pattern is specifically engineered to distribute support evenly across the entire media surface, preventing the localized stress concentrations that can cause premature media failure.

Application Overview

Primary Applications: Indoor and Outdoor HVAC Systems

The HPG101825 media pad holding frame serves commercial and industrial HVAC applications where the 18x25x1 nominal filter size is specified. This size is commonly found in:

• Commercial Building HVAC: Rooftop units, air handling units, and packaged HVAC equipment serving retail spaces, office buildings, and institutional facilities
• Industrial Ventilation: Process air handling systems, paint booth makeup air units, and industrial air filtration systems requiring particulate removal
• Light Manufacturing: Facility ventilation systems in assembly plants, warehousing operations, and distribution centers
• Institutional Buildings: Schools, hospitals, government facilities, and public buildings with commercial-grade HVAC equipment
• Multi-Family Residential: Apartment complexes, condominiums, and multi-unit residential buildings with centralized HVAC systems
• Data Centers: Environmental control systems requiring reliable filtration with predictable pressure drop characteristics
• Clean Rooms: Pre-filtration stages in controlled environment applications where downstream high-efficiency filters require protection from larger particulates
• Food Processing: Air handling systems in food manufacturing, processing, and packaging facilities requiring sanitary design and washable components

1-Inch Depth Benefits

The 1-inch (0.875″ actual) depth of the HPG101825 provides specific advantages when using aluminum mesh or similar media types:

• 5-Ply Aluminum Mesh Construction: The 1-inch depth accommodates five layers of aluminum mesh media, providing enhanced dust holding capacity compared to single or double-layer configurations
• 68 Grams Per Square Foot Dust Capacity: Five-layer aluminum mesh construction delivers 68 grams per square foot of arrestance capacity, significantly extending service intervals between media cleaning or replacement
• 43% Arrestance at 350 FPM: Proven arrestance efficiency of 43% at 350 feet per minute face velocity, providing effective removal of larger airborne particulates
• Washable and Reusable Media: When using aluminum mesh media, the filter pad can be washed and reused multiple times, further reducing operating costs
• UL Classified 900: The complete assembly including frame and aluminum mesh media is UL Classified for use in commercial HVAC applications
• High Temperature Capability: Aluminum mesh media combined with the galvanized steel frame provides reliable performance at elevated temperatures up to 325°F
• Low Initial Resistance: The expanded aluminum mesh provides low initial pressure drop, minimizing energy consumption while delivering effective filtration
• Visible Loading: Aluminum mesh allows visual inspection to determine when cleaning or replacement is needed, unlike opaque filter media

The 1-inch depth represents the optimal balance between filtration capacity and pressure drop for commercial HVAC applications. Thinner filters sacrifice dust holding capacity and require more frequent servicing, while thicker filters may not fit standard commercial HVAC equipment filter tracks. The 18x25x1 nominal size provides 450 square inches of filter area, delivering substantial airflow capacity in a single filter position.

Galvanized Steel Construction Advantages

The HPG101825’s galvanized steel construction provides multiple performance advantages over alternative frame materials:

Corrosion Resistance: Hot-dip galvanizing applies a metallurgically bonded zinc coating to the steel substrate, providing superior corrosion protection compared to paint or powder coating. The zinc coating acts as a sacrificial anode, protecting the underlying steel even if the coating is scratched or damaged. This corrosion resistance is essential in high-humidity environments, outdoor installations, and applications where the filter pad holding frame may be exposed to water during cleaning procedures.

High-Temperature Performance: Galvanized steel maintains structural integrity and dimensional stability at temperatures up to 325°F, well beyond the operating range of plastic or aluminum frames. This temperature capability allows installation in applications such as dryer exhaust systems, industrial process air handling, and equipment where elevated temperatures occur during normal operation or emergency conditions.

Structural Rigidity: The 24 gauge steel frame provides exceptional rigidity that prevents flexing, warping, or distortion under differential pressure loads. This structural stability ensures the frame maintains proper fit within the filter housing, preventing air bypass gaps that would allow unfiltered air to compromise system performance. The rigid frame also supports the filter media without sagging, maintaining uniform airflow distribution across the entire filter surface.

Long Service Life: With proper handling and normal maintenance procedures, the HPG101825 galvanized steel holding frame delivers 5-10 years of reliable service life. The durable construction withstands repeated filter media replacement cycles without structural degradation, joint failure, or dimensional changes that would necessitate frame replacement.

Fire Resistance: Galvanized steel is non-combustible and will not contribute fuel to a fire event. This inherent fire resistance provides safety advantages in commercial and industrial applications where building codes and insurance requirements mandate non-combustible materials in air handling systems.

Dimensional Stability: Unlike plastic frames that can warp or distort with temperature changes, galvanized steel maintains precise dimensions across the full operating temperature range. This dimensional stability ensures consistent fit and seal performance throughout the frame’s service life.

Recyclability: At end of service life, galvanized steel is 100% recyclable with no loss of material properties. The steel and zinc coating can be separated and recycled into new products, supporting sustainable building practices and LEED certification requirements.

Filter Media Compatibility

The HPG101825 media pad holding frame accommodates a wide range of 1-inch thick filter media types, allowing facility managers to select the optimal filtration solution for specific application requirements:

Standard Fiberglass Filter Pads: Economy-grade fiberglass media provides basic particulate filtration for general ventilation applications. These disposable pads offer low initial cost and are typically replaced monthly or quarterly depending on loading conditions. Fiberglass media is ideal for applications where filtration requirements are modest and frequent replacement is acceptable.

Polyester Media: Synthetic polyester filter pads deliver enhanced dust holding capacity and mechanical strength compared to fiberglass alternatives. The polyester fibers resist moisture better than fiberglass, making them suitable for high-humidity applications or installations where occasional condensation may occur. Polyester media maintains its structure and efficiency even when wet, whereas fiberglass media can collapse or disintegrate when exposed to moisture.

Activated Carbon Sheets: For applications requiring odor control, volatile organic compound (VOC) removal, or chemical filtration, activated carbon sheets can be installed in the HPG101825 frame. These specialty media types combine particulate filtration with chemical adsorption, addressing both air quality and odor control requirements. Carbon media is commonly specified in restaurants, food processing facilities, chemical plants, and applications where odor control is essential.

Antimicrobial-Treated Media: Filter pads with antimicrobial treatments inhibit bacterial and fungal growth on the filter media surface. This is particularly important in healthcare facilities, food processing operations, and environments where microbial contamination must be controlled. Antimicrobial media helps maintain indoor air quality and prevents the filter system from becoming a breeding ground for harmful microorganisms.

High-Temperature Media: Specialty synthetic media designed for elevated temperature applications can withstand continuous exposure to temperatures up to 325°F. These media types are essential in industrial process air handling, commercial cooking exhaust makeup air, and other applications where standard filter media would degrade or fail.

Aluminum Mesh Media: Multi-layer aluminum mesh provides washable, reusable filtration with excellent durability and high temperature resistance. Five-layer aluminum mesh construction delivers 68 grams per square foot dust capacity with 43% arrestance at 350 FPM. The aluminum mesh can be removed, washed, and reinstalled multiple times, providing the lowest long-term operating cost of any media type.

Pleated Media Inserts: While the HPG101825 is designed for flat filter pad media, some applications may use pleated media inserts that provide higher efficiency filtration within the 1-inch depth constraint. Pleated media increases surface area compared to flat pads, delivering improved dust holding capacity and lower pressure drop at equivalent efficiency levels.

Installation Procedures

Proper installation of the HPG101825 media pad holding frame ensures optimal performance, longevity, and system efficiency:

Pre-Installation Inspection: Before installation, inspect the filter housing to ensure it is clean, free of debris, and properly sized for 18x25x1 nominal filters. Verify that the actual opening dimensions accommodate the 17.5″ H x 24.5″ W x 0.875″ D frame with appropriate clearance. Check that filter tracks or retention hardware are present and properly aligned to support the filter weight and resist pressure differential forces.

Media Installation: If installing filter media before mounting the frame, position the frame with the face grid side down on a clean, flat work surface. Place the filter media pad into the frame cavity, ensuring it extends fully to all four edges without gaps or compression. The media should lay flat against the face grid without wrinkles or folds that would create airflow restrictions or bypass paths. For applications using multiple media layers or specialty media, ensure proper orientation according to manufacturer recommendations.

Frame Mounting: Install the frame into the filter housing with the face grid side facing the air exit (downstream) direction. The face grid provides media support and must face away from the incoming airflow. Slide the frame fully into the filter tracks until it seats firmly against the back stops or gaskets. Verify that the frame is properly positioned without binding, tilting, or gaps that would allow air bypass.

Seal Verification: After installation, visually inspect around the entire frame perimeter to confirm proper sealing against the filter housing. Any gaps or misalignment will allow unfiltered air bypass, reducing system efficiency and potentially causing downstream contamination. If gaps are present, adjust the frame position or address filter housing dimensional issues before placing the system into service.

Airflow Direction: Confirm proper airflow direction through the filter assembly. The face grid must face downstream (clean air side) to provide support for the filter media under positive pressure conditions. Installing the frame backwards will cause the media to press against the smooth upstream face without support, potentially causing media dislodgement or damage.

Initial System Start-Up: After installation, start the HVAC system and monitor for unusual noise, vibration, or airflow restriction. Excessive noise may indicate improper frame installation, while significantly reduced airflow suggests media blockage or incorrect media selection. During initial operation, verify that the frame remains properly seated and does not shift or vibrate due to system pressure fluctuations.

Maintenance and Media Replacement

Regular maintenance and timely media replacement ensure the HPG101825 continues to deliver optimal performance throughout its service life:

Inspection Frequency: Establish a regular inspection schedule based on application conditions, typically ranging from monthly inspections in heavy-loading industrial environments to quarterly inspections in light commercial applications. During inspection, assess media loading by visual examination or pressure drop measurement to determine when media replacement is necessary.

Pressure Drop Monitoring: Implement pressure drop monitoring across the filter bank to track media loading and determine optimal replacement intervals. Install manometers or differential pressure switches to measure pressure drop across the filters. Establish baseline pressure drop with clean media, then schedule replacement when pressure drop reaches 2-3 times the initial value or when airflow reduction becomes noticeable.

Media Replacement Procedure: To replace filter media, first shut down the HVAC system to prevent media fragments from entering downstream equipment. Remove the HPG101825 frame from the filter housing by sliding it out of the filter tracks. With the frame removed from the housing, extract the used filter media and dispose of it according to facility waste handling procedures and local regulations. Inspect the frame for damage, corrosion, or structural degradation before reinstalling. Install new filter media, ensuring it extends fully to all frame edges, then reinstall the complete assembly in the filter housing.

Frame Cleaning: Periodically clean the HPG101825 frame to remove accumulated dust, debris, and surface contamination. Remove the frame from service and wash it using pressure washing, spray washing, or manual cleaning with mild detergent solutions. The galvanized steel construction tolerates water exposure without corrosion risk. After washing, allow the frame to air dry completely before reinstalling to prevent moisture transfer to fresh filter media.

Storage: Store spare frames and filter media in a clean, dry location protected from physical damage, moisture, and temperature extremes. Store frames laying flat or standing on edge to prevent distortion. Keep filter media in original packaging until use to maintain cleanliness and protect from moisture absorption.

Frame Inspection: During each media replacement cycle, inspect the frame for signs of damage, corrosion, or structural degradation. Check corner joints for separation, examine the face grid for damage or detachment, and verify that the frame maintains proper dimensions without warping or distortion. Replace the frame if structural damage, significant corrosion, or dimensional changes are present.

Economic Advantages

The HPG101825 media filter pad holding frame system delivers substantial long-term economic advantages compared to disposable filter alternatives:

Reduced Filter Costs: By investing once in the durable holding frame and replacing only the filter media, facilities typically reduce long-term filtration costs by 60-80% compared to complete disposable filter replacement. This cost reduction becomes increasingly significant in applications requiring frequent filter changes due to heavy loading conditions.

Lower Labor Costs: Media replacement requires less handling time than complete filter replacement, reducing labor costs associated with filter maintenance. The lighter weight of filter media pads compared to complete filter assemblies also reduces physical demands on maintenance personnel and decreases risk of injury during filter servicing operations.

Reduced Waste Generation: Replacing only the filter media instead of the entire filter assembly dramatically reduces waste generation, lowering disposal costs and supporting environmental sustainability goals. The frame remains in service for 5-10 years, eliminating the recurring disposal of galvanized steel frame components with each filter change.

Extended Service Life: The HPG101825’s 5-10 year service life means the frame investment is amortized over hundreds of filter media replacement cycles, reducing the effective per-change cost to minimal levels. This extended service life also reduces the administrative burden of reordering, receiving, and managing filter inventory.

Predictable Budgeting: the filter pad holding frame system provides predictable long-term costs, making budget planning and cost projection more accurate. After the initial frame investment, ongoing costs consist only of replacement media pads at predictable intervals based on application loading conditions.

Energy Savings: When using aluminum mesh media, the washable and reusable characteristics allow the filter to be cleaned and returned to service multiple times before replacement. This further reduces media costs and extends the interval between media purchases. Additionally, maintaining optimal pressure drop through timely media service minimizes fan energy consumption.

Technical Performance Data

The HPG101825 delivers consistent, predictable performance across a wide range of HVAC applications:

Airflow Capacity: With 450 square inches of filter area (17.5″ x 24.5″), the HPG101825 supports substantial airflow volumes at acceptable face velocities. At 300 feet per minute (FPM) face velocity, a single filter passes approximately 940 cubic feet per minute (CFM). At 500 FPM face velocity, airflow capacity reaches approximately 1,560 CFM per filter. Face velocity should be selected based on media type, efficiency requirements, and pressure drop constraints.

Pressure Drop: Initial pressure drop depends on the specific filter media installed in the frame. Typical pressure drop ranges for common media types at 350 FPM face velocity include: fiberglass pads 0.15-0.25 inches water gauge (w.g.), polyester media 0.20-0.30 inches w.g., and five-layer aluminum mesh approximately 0.25 inches w.g. Final pressure drop before media replacement is typically 2-3 times the initial value.

Filtration Efficiency: Filtration efficiency is determined by the specific media type installed in the frame. Standard fiberglass and polyester pads typically provide 20-40% arrestance efficiency for larger particles. Five-layer aluminum mesh delivers 43% arrestance at 350 FPM face velocity. Higher efficiency media types can achieve MERV 8 or higher ratings when appropriate pleated media inserts are used.

Dust Holding Capacity: Dust holding capacity varies with media type. Standard 1-inch thick fiberglass pads typically hold 50-80 grams per square foot before reaching final pressure drop. Five-layer aluminum mesh provides 68 grams per square foot dust capacity. Higher capacity media types with pleated or depth-loading construction can exceed 100 grams per square foot in the 1-inch depth.

Temperature Performance: The HPG101825 galvanized steel frame maintains structural integrity and dimensional stability across the full -40°F to +325°F temperature range. This broad temperature capability ensures reliable performance in both extreme cold outdoor installations and elevated temperature industrial applications. Filter media selection must be compatible with application temperature requirements.

Humidity Resistance: The galvanized steel construction provides excellent resistance to humidity and moisture exposure. The frame can withstand 100% relative humidity conditions without corrosion or structural degradation. Corner drain holes allow water evacuation in high-moisture applications or when frames are washed during maintenance procedures.

Sizing and Dimensional Considerations

Understanding nominal versus actual filter dimensions is essential for proper filter selection and housing compatibility:

Nominal Size: The HPG101825 has a nominal size of 18x25x1, which represents the approximate dimensions in inches using whole number values. Nominal sizing is the standard convention used throughout the HVAC industry for filter specification and ordering.

Actual Dimensions: The actual dimensions of the HPG101825 are 17.5″ H x 24.5″ W x 0.875″ D. These actual dimensions are smaller than nominal to provide clearance for installation in standard filter housings. The height and width are each 0.5 inches smaller than nominal, while the depth is 0.125 inches smaller than the 1-inch nominal depth.

Filter Housing Requirements: The filter housing must provide minimum opening dimensions of 17.5″ H x 24.5″ W to accommodate the HPG101825 frame. Filter tracks or retention hardware should provide depth clearance of at least 0.875 inches, plus additional clearance for filter media thickness and installation/removal. Standard commercial HVAC equipment designed for 18x25x1 nominal filters will accommodate this filter pad holding frame.

Multiple Filter Banks: When multiple filters are installed in a filter bank configuration, each filter occupies approximately 18 inches of height and 25 inches of width including spacing between filters. Account for filter track dimensions and structural components when calculating total filter bank dimensions.

Media Pad Sizing: Filter media pads for the HPG101825 should be cut to approximately 17.5″ x 24.5″ to fit properly within the frame cavity. Some minor trimming may be necessary depending on media manufacturing tolerances. The media should extend fully to all four frame edges without gaps, but should not be oversized to the point of creating compression or buckling.

Regulatory Compliance and Certifications

The HPG101825 meets or exceeds multiple industry standards and regulatory requirements:

UL Classified 900: Underwriters Laboratories has tested and classified the HPG Series media pad holding frames for continuous operation at temperatures up to 325°F in commercial and light industrial HVAC applications. This third-party certification provides assurance that the product has undergone rigorous testing and meets established safety standards for commercial use.

Made in USA: Manufactured domestically by American Metal Filter Company, the HPG101825 complies with American manufacturing standards and quality requirements. Domestic manufacturing provides supply chain reliability, supports American jobs, and may satisfy Buy American requirements for government and institutional projects.

Building Code Compliance: The galvanized steel construction and UL Classified rating support compliance with model building codes including International Building Code (IBC), International Mechanical Code (IMC), and NFPA standards. The non-combustible frame material satisfies fire safety requirements for installation in commercial building HVAC systems.

OSHA Compliance: The filter frame design includes corner drain holes and washable construction that supports cleaning and maintenance procedures. This design facilitates compliance with OSHA indoor air quality guidelines and workplace safety requirements for commercial and industrial facilities.

EPA Considerations: By reducing waste generation through the use of replaceable filter pad media instead of complete disposable filters, the HPG101825 supports EPA waste reduction goals and may contribute to green building certification programs such as LEED.

Optional Wire Gate Feature

A hinged wire gate can be specified as an optional feature when ordering the HPG101825 media pad holding frame:

Convenience: The optional hinged wire gate installs on the air entrance side of the holding frame, providing a convenient opening for filter media insertion and removal without requiring frame removal from the filter housing. This feature is particularly valuable in applications where filter access is difficult or where frequent media changes are required.

Ordering Specification: The wire gate is not included as standard equipment and must be specifically requested when ordering. Specify “with wire gate” or “include optional wire gate” when placing orders to ensure this feature is included. Retrofit installation of wire gates on existing frames is not typically supported.

Construction: The wire gate consists of a galvanized steel wire frame with expanded metal fill material, matching the construction and finish of the main air filter frame. The gate is attached with hinges on one edge and includes a latch or fastener on the opposite edge to secure it closed during operation.

Operation: To replace filter media with the wire gate option, unlatch the gate, swing it open to access the frame cavity, remove the used media, install fresh media, and close and latch the gate. The entire media replacement procedure can be completed without removing the frame from the filter housing, reducing maintenance time and labor costs.

Applications: The wire gate option is most beneficial in applications such as vertical filter banks where frame removal is physically difficult, high-access installations where filter access requires ladders or lifts, or applications requiring very frequent media changes where the time savings of not removing the frame provides significant value.

Considerations: The wire gate adds modest weight and cost to the frame. In applications where frame removal is straightforward and media changes are infrequent, the standard frame without wire gate typically provides the best value. Evaluate the specific application requirements and maintenance procedures when deciding whether the optional wire gate feature is justified.

Quality Assurance and Manufacturing

American Metal Filter Company manufactures the HPG101825 using rigorous quality control procedures and American manufacturing standards:

Material Selection: All galvanized steel components meet ASTM specifications for gauge thickness, coating weight, and mechanical properties. The hot-dip galvanizing process applies a minimum zinc coating weight per ASTM A653 standards, ensuring consistent corrosion protection and surface finish.

Dimensional Accuracy: Precision forming and cutting equipment maintains frame dimensions within tight tolerances, ensuring consistent fit in standard filter housings. Each frame is manufactured to 17.5″ ± 0.0625″ height and 24.5″ ± 0.0625″ width, with corner angles held to 90° ± 0.5°.

Assembly Procedures: Mitered corner joints are secured with industrial pop-rivets installed using calibrated pneumatic tooling. The face grid is spot-welded to the frame using resistance welding equipment that provides consistent, high-strength welds at specified intervals around the perimeter.

Inspection: Each frame undergoes visual inspection for dimensional accuracy, corner joint integrity, face grid attachment, and surface finish quality. Frames that do not meet quality standards are rejected and reworked or scrapped rather than shipped to customers.

Packaging: Frames are packaged in cartons of 12 units with protective corner reinforcement and internal separators to prevent shipping damage. The standard carton pack of 12 units weighing 33.6 lbs total provides efficient shipping and handling while minimizing packaging waste.

Environmental Considerations

The HPG101825 media pad holding frame supports environmental sustainability through multiple mechanisms:

Waste Reduction: By replacing only the filter media instead of the entire filter assembly, the HPG101825 dramatically reduces waste generation compared to disposable filter alternatives. Over a 10-year service life with monthly media changes, the holding frame system generates approximately 85% less waste by weight than complete disposable filter replacement.

Recyclability: At end of service life, the galvanized steel frame is 100% recyclable. The steel and zinc coating can be separated during the recycling process and reprocessed into new products without loss of material properties. This closed-loop recyclability supports circular economy principles and reduces demand for virgin materials.

Energy Efficiency: Maintaining optimal filter pressure drop through timely media replacement minimizes HVAC fan energy consumption. The HPG101825’s rigid construction and proper sealing prevent air bypass, ensuring all airflow passes through the filter media for maximum system efficiency.

Durability: The 5-10 year service life eliminates the recurring environmental impacts associated with manufacturing, transporting, and disposing of replacement filters. This extended service life provides significant environmental benefits through reduced resource consumption and lower lifetime carbon footprint.

LEED Contribution: The waste reduction, recyclability, and durability characteristics of the HPG101825 can contribute toward LEED certification credits in the Materials and Resources category. Documentation of waste diversion and recycled content supports green building certification efforts.

Troubleshooting Common Issues

Address common HPG101825 installation and performance issues with these troubleshooting guidelines:

Air Bypass: If unfiltered air bypasses around the air filter frame, verify that the frame is fully seated in the filter tracks and that the housing opening dimensions are correct for 18x25x1 nominal filters. Check for warped or damaged frame edges that would prevent proper sealing. Ensure filter track alignment and spacing match the 0.875″ frame depth.

Excessive Pressure Drop: If system pressure drop is higher than expected, verify that the correct media type is installed and that the media is not excessively compressed or wrinkled. Confirm that airflow direction is correct with the face grid facing downstream. Check for media that extends beyond the frame edges and blocks airflow. Consider whether media replacement is overdue.

Media Sagging: If filter media sags away from the face grid, verify that the frame is installed in the correct orientation with the face grid facing downstream (air exit side). Check that the media is properly sized to fit the frame cavity without excessive slack. Confirm that differential pressure is not exceeding media structural limitations.

Frame Corrosion: If corrosion develops on the galvanized steel frame, investigate whether the frame has been exposed to acidic or alkaline chemical environments beyond its design parameters. Evaluate whether washing procedures are using inappropriate cleaning chemicals. Consider whether the application environment requires stainless steel construction instead of galvanized steel.

Vibration or Noise: If the frame vibrates or produces noise during system operation, verify that it is fully seated in the filter tracks without gaps or loose fit. Check that the face grid is securely attached without detachment or loose sections. Confirm that the frame is not contacting adjacent filters or housing components that would cause rattling.

Comparison to Alternative Filter Types

Understanding how the HPG101825 media pad holding frame compares to alternative filter types helps inform proper filter selection:

Complete Disposable Filters: Standard disposable filters include both frame and media in a single-use assembly. While convenient, disposable filters generate significantly more waste and cost 3-5 times more than replacement media over the long term. The HPG101825 provides superior value in applications with ongoing filtration requirements where the one-time frame investment pays for itself within 6-12 months.

Washable Aluminum Mesh Filters: Permanent washable filters use multiple layers of aluminum mesh in a permanent frame. These provide the lowest long-term operating cost when maintained properly, but require washing facilities and labor. The HPG101825 with aluminum mesh media provides similar characteristics, but allows media replacement if desired rather than requiring washing.

Pleated Disposable Filters: Pleated filters provide higher efficiency and dust holding capacity than flat pad media, but at substantially higher cost per filter. The HPG101825 cannot accommodate standard pleated filters due to depth constraints, making it most appropriate for applications where basic particulate filtration is sufficient.

Electronic Air Cleaners: Electronic air cleaners use electrostatic precipitation to capture particles, providing high efficiency with low pressure drop. However, electronic air cleaners require electrical power, regular cleaning, and have high initial cost. The HPG101825 provides a passive filtration solution with no power consumption and minimal maintenance requirements.

HEPA Filters: High-efficiency particulate air (HEPA) filters provide 99.97% efficiency for 0.3 micron particles, far exceeding the capability of media pad holding frames. However, HEPA filters require substantial pressure drop and are used only in critical applications requiring the highest filtration levels. The HPG101825 is appropriate for general ventilation where HEPA efficiency is not required.

Related Products

Consider these related products when specifying filtration solutions:

• HPG101220: 12x20x1 media pad holding frame for smaller filter openings
• HPG101224: 12x24x1 media pad holding frame in a common commercial size
• HPG101420: 14x20x1 media pad holding frame for mid-size applications
• HPG101424: 14x24x1 media pad holding frame, another common commercial size
• HPG101425: 14x25x1 media pad holding frame for standard residential/commercial equipment
• HPG101520: 15x20x1 media pad holding frame for specific equipment requirements
• HPG101616: 16x16x1 media pad holding frame for square filter housings
• HPG101620: 16x20x1 media pad holding frame, common in residential systems
• HPG101625: 16x25x1 media pad holding frame for standard equipment
• HPG101630: 16x30x1 media pad holding frame for larger openings
• HPG101818: 18x18x1 media pad holding frame for square configurations
• HPG101820: 18x20x1 media pad holding frame for compact installations
• HPG101824: 18x24x1 media pad holding frame for commercial applications
• HPG102020: 20x20x1 media pad holding frame for square housings
• HPG102025: 20x25x1 media pad holding frame for large equipment
• HPG102424: 24x24x1 media pad holding frame for square commercial units
• HPG201224: 12x24x2 media pad holding frame for 2-inch depth applications
• HPG201616: 16x16x2 media pad holding frame with enhanced capacity
• HPG201620: 16x20x2 media pad holding frame for higher efficiency
• HPG201625: 16x25x2 media pad holding frame, 2-inch version
• HPG202020: 20x20x2 media pad holding frame for 2-inch applications
• HPG202024: 20x24x2 media pad holding frame for commercial systems
• HPG202025: 20x25x2 media pad holding frame for enhanced filtration
• HPG202424: 24x24x2 media pad holding frame for large commercial applications
• HPGG101224: 12x24x1 media pad holding frame with hinged access gate
• HPGG101620: 16x20x1 media pad holding frame with hinged access gate
• HPGG101625: 16x25x1 media pad holding frame with hinged access gate
• HPGG102020: 20x20x1 media pad holding frame with hinged access gate
• HPGG102025: 20x25x1 media pad holding frame with hinged access gate
• HPGG102424: 24x24x1 media pad holding frame with hinged access gate
• HPGG201224: 12x24x2 media pad holding frame with hinged access gate
• HPGG201620: 16x20x2 media pad holding frame with hinged access gate
• HPGG201625: 16x25x2 media pad holding frame with hinged access gate
• HPGG202020: 20x20x2 media pad holding frame with hinged access gate
• HPGG202025: 20x25x2 media pad holding frame with hinged access gate
• HPGG202424: 24x24x2 media pad holding frame with hinged access gate
• Replacement Filter Media: Various media types available in 18x25x1 size including fiberglass, polyester, activated carbon, and aluminum mesh

Frequently Asked Questions

What types of filter media can I use with this holding frame?

The HPG101825 media pad holding frame accommodates various filter media types including standard fiberglass filter pads, polyester media, activated carbon sheets, antimicrobial-treated media, high-temperature specialty media, aluminum mesh, and specialty filtration materials with 1-inch thickness. Select media based on your specific application requirements for efficiency, dust holding capacity, temperature resistance, and cost considerations.

How is this different from a complete disposable filter?

This media pad holding frame is a permanent reusable frame designed for decades of service, where you replace only the filter media instead of discarding the entire filter assembly. With this holding frame system, you invest once in the durable galvanized steel frame and then purchase only replacement media pads, typically reducing long-term filtration costs by 60-80%. Complete disposable filters include both frame and media and must be entirely replaced at each service interval, generating substantially more waste and higher ongoing costs.

How long does the frame itself last?

With proper handling and normal maintenance procedures, the HPG101825 galvanized steel holding frame delivers 5-10 years of reliable service life. The durable 24 gauge galvanized steel construction resists corrosion, maintains dimensional stability, and withstands repeated filter media replacement cycles without structural degradation. The frame’s service life depends on application severity, maintenance practices, and handling care during media replacement procedures.

Does this filter pad holding frame come with filter media included?

No, the HPG101825 media pad holding frame is sold as a standalone component without filter media included. This allows you to select the specific filter media type most appropriate for your application requirements. Purchase replacement media separately based on your efficiency needs, operating conditions, and budget constraints.

What does the UL Classified 900 rating mean?

UL Classified 900 indicates this holding frame has been tested and classified by Underwriters Laboratories for continuous operation at temperatures up to 325°F in commercial and light industrial HVAC applications. This third-party certification provides assurance that the product has undergone rigorous testing and meets established safety standards. The UL classification supports code compliance and may be required for installation in commercial buildings.

Can this filter pad holding frame be cleaned or washed?

Yes, the galvanized steel construction allows periodic cleaning to maintain optimal condition throughout the frame’s multi-decade service life. Remove accumulated dust or surface contamination using pressure washing, spray washing, or manual cleaning with mild detergent solutions. The corner drain holes facilitate water evacuation during washing. After cleaning, allow the frame to air dry completely before reinstalling to prevent moisture transfer to fresh filter media.

What is the optional wire gate feature?

The optional hinged wire gate installs on the air entrance side of the holding frame when specified during ordering, providing a convenient opening for filter media insertion and removal without requiring frame removal from the filter housing. The wire gate must be specifically requested when ordering as it is not included as standard equipment. This feature is most beneficial in applications where filter access is difficult or where very frequent media changes are required.

Is this filter pad holding frame compatible with existing filter housings?

The HPG101825 fits standard 18x25x1 nominal filter housings with actual opening dimensions accommodating 17.5″ H x 24.5″ W x 0.875″ D frames. This represents industry-standard sizing used throughout commercial HVAC equipment from major manufacturers. Verify your filter housing dimensions before ordering to ensure compatibility. The frame should slide smoothly into the filter tracks with minimal clearance around the perimeter.

Can I install filter media before mounting the frame?

Yes, you can install filter media in the frame before mounting it in the filter housing. Position the frame with the face grid side down on a clean work surface, insert the filter media ensuring it extends fully to all edges without gaps, then install the frame with media in place into your filter housing. This approach is often easier than trying to insert media after the frame is already mounted in the housing.

Why choose a media pad holding frame instead of washable filters?

Media pad holding frames suit applications where disposable media replacement is preferred over filter washing procedures. filter holding frames frames also allow flexibility to change filtration efficiency levels by selecting different media types, whereas washable filters have fixed efficiency characteristics. Additionally, some facilities lack adequate washing facilities or prefer to avoid the water usage and labor associated with filter washing, making disposable media replacement more practical despite washable filters having lower per-cycle costs.

What is the difference between HPG and HPGG models?

HPG models are standard media pad holding frames requiring traditional filter media replacement by removing the frame from the housing. HPGG models include factory-installed hinged access gates that allow convenient filter media replacement without removing the frame from the filter housing. The HPG101825 requires frame removal for media changes, though an optional hinged wire gate can be specified when ordering if desired. HPGG models cost more but provide convenience in applications requiring frequent media changes or difficult filter access.

How do I determine when to replace filter media?

Monitor pressure drop across the filter bank, with replacement recommended when pressure drop reaches 2-3 times the initial clean filter value. Visual inspection of media loading can also indicate replacement timing – when the media surface is substantially discolored or loaded with dust, replacement is likely needed. Many facilities establish replacement schedules based on experience, typically ranging from monthly changes in heavy-loading industrial applications to quarterly or semi-annual changes in light commercial environments.

Can this frame be used in outdoor installations?

Yes, the galvanized steel construction provides excellent corrosion resistance for outdoor installations. The frame can withstand temperature extremes from -40°F to +325°F and tolerates 100% humidity conditions. Select filter media appropriate for outdoor use, considering moisture resistance, temperature capability, and UV stability if exposed to direct sunlight. Ensure the filter housing provides adequate weather protection to prevent direct water entry.

What face velocities are recommended?

Recommended face velocity depends on the media type and application requirements. Standard fiberglass and polyester pads typically operate at 300-500 FPM face velocity. Aluminum mesh media commonly operates at 350-400 FPM. Higher face velocities increase pressure drop and may reduce media service life, while lower velocities improve efficiency and extend service intervals. Consult media manufacturer recommendations for specific velocity limits.

Is the frame reversible for different airflow directions?

No, the HPG101825 has a specific installation orientation. The face grid must face downstream (air exit side) to provide media support under positive pressure conditions. The face grid side is clearly visible as the side with the expanded metal grid. Installing the frame backwards will cause improper media support and potential media displacement or damage.

Ordering Information

To order the HPG101825 18x25x1 Nominal Air Filter Pad Holding Frame:

• Base Model: HPG101825 (standard frame without wire gate)
• Optional Wire Gate: Specify “with optional wire gate” when ordering if wire gate is desired
• Quantity: Standard carton pack is 12 units per carton (33.6 lbs total)
• Filter Media: Specify filter media separately – the frame is sold without media
• Lead Time: Contact manufacturer for current lead times and availability
• Custom Sizes: Custom sizes available – contact manufacturer for quotation

For technical support, custom size inquiries, or ordering assistance, contact American Metal Filter Company directly. Provide complete application details including HVAC system type, operating conditions, required filtration efficiency, and any special requirements or environmental considerations.

Warranty Information

American Metal Filter Company warrants the HPG101825 to be free from defects in materials and workmanship under normal use and service. The warranty covers manufacturing defects including inadequate galvanizing, improper corner joint assembly, defective face grid attachment, and dimensional errors outside specified tolerances. The warranty does not cover damage from mishandling, improper installation, use outside design parameters, or normal wear and tear. Consult American Metal Filter Company for complete warranty terms, conditions, and claim procedures.

Conclusion

The HPG101825 18x25x1 Nominal Air Filter Pad Holding Frame delivers an optimal combination of durability, economy, and performance for commercial and industrial HVAC filtration applications. The heavy-duty galvanized steel construction ensures decades of reliable service, while the replaceable media design dramatically reduces long-term filtration costs compared to disposable alternatives. With UL Classified 900 rating, temperature capability to 325°F, and compatibility with diverse filter media types, the HPG101825 provides a versatile filtration solution that adapts to changing application requirements throughout its extended service life.

Whether specifying new HVAC equipment, upgrading existing filtration systems, or seeking to reduce ongoing filter replacement costs, the HPG101825 represents a proven solution backed by American manufacturing quality and decades of field experience. The frame’s 5-10 year service life, minimal maintenance requirements, and substantial waste reduction support both economic and environmental objectives while delivering consistent, reliable filtration performance.

For applications requiring the 18x25x1 filter size, the HPG101825 combines industrial-grade construction with practical economy, making it the preferred choice for facility managers, HVAC contractors, and building owners who demand long-term value and performance from their filtration investments.