The Koch Multi-Test Rigid MTR 45 Cartridge is a rigid self-supported extended-surface filter that drops directly into the air handler housing — no basket framework required. The rigid construction holds the cartridge geometry on its own, so the filter can be installed in housings that don’t have an existing basket or in systems where the original basket has been removed. The MTR 45 tier delivers 45% dust spot efficiency per ASHRAE 52.1, which corresponds to approximately MERV 11 per the modern ASHRAE 52.2 test standard. Specified for mid-efficiency commercial HVAC and prefilter applications ahead of higher-MERV final stages.
Rigid self-supported design (no basket required)
This is the critical differentiator for the Multi-Test Rigid line: the cartridge supports itself. The frame and media construction hold their shape under airflow without external bracing. That means:
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No basket framework needed. The cartridge installs directly into the housing — useful when the original equipment basket is missing, damaged, or wasn’t part of the original specification.
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Direct compatibility with side-access housings, top-load cabinets, and front-load AHU racks that don’t use Cambridge or Farr-style baskets.
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Simplified installation — one component to install, replace, and dispose of. No basket cleaning or basket replacement.
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Stable geometry under airflow — the rigid construction won’t collapse or distort under high-velocity airflow or pressure spikes.
For applications that do have Farr HP basket framework already installed, see the Multi-Test Cartridge line (collapsible cartridges designed to fit Farr HP baskets). For Cambridge Hi-Cap and Side-Cap framework, see the Duo-Cap line. The Multi-Test Rigid is the right pick when you don’t need or want a basket in your system.
Why "MTR 45" naming — ASHRAE 52.1 vs 52.2
The Multi-Test Rigid line uses the older ASHRAE 52.1 dust spot efficiency percentages for tier naming — the number after "MTR" is the approximate dust spot efficiency. For modern HVAC documentation against ASHRAE 52.2 (MERV), the industry-standard correspondence is:
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MTR 45 (45% dust spot) → approximately MERV 11
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MTR 85 (85% dust spot) → approximately MERV 13
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MTR 95 (95% dust spot) → approximately MERV 14
For applications requiring formal MERV documentation, reference Koch bulletin K-1080-A or contact us for the latest spec sheet.
MTR 45 performance characteristics
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Initial pressure drop (12″ depth): 0.16″ w.g.
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Initial pressure drop (24″ depth): 0.40″ w.g.
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Recommended final pressure drop: 0.70″ w.g.
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Efficiency: 45% dust spot efficiency per ASHRAE 52.1; approximately MERV 11 per ASHRAE 52.2
Design and construction
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Configuration: Rigid self-supported extended-surface cartridge filter
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Media: Synthetic high-efficiency media with rigid pleat structure
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Frame compatibility: Drops directly into housings; no basket framework required
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Efficiency rating: 45% dust spot efficiency per ASHRAE 52.1; approximately MERV 11 per ASHRAE 52.2
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Reference bulletin: Koch K-1080-A
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Available depths: 12″ and 24″ (deeper cartridges deliver longer service life and lower pressure drop at equivalent capture)
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Available face sizes: 12x24 and 24x24
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Sold by the case. Carton quantity varies by size: 12x24x12 ships 4 per case; 24x24x12 ships 2 per case; 24x24x24 ships 1 per case; 12x24x24 ships 2 per case. The variant price is the case price.
When the Multi-Test Rigid MTR 45 is specified
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Mid-efficiency commercial HVAC final filtration — office buildings, schools, hotels where ~MERV 11 capture is the design target and basket framework isn’t available
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Prefilter stages ahead of MERV 13+ final stages in multi-stage systems — the rigid form factor protects downstream filters and extends their service life
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Light-industrial systems in housings without basket framework
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Variable-air-volume systems where the rigid geometry handles airflow swings without flexing
What ~MERV 11 captures
Captures fine dust, smoke, auto fumes, and most airborne particles down to 1 micron. Strong general-purpose efficiency for offices, schools, hotels, and light industrial.
Choosing across the Multi-Test Rigid line
Koch offers three efficiency tiers in the Multi-Test Rigid line, all rigid self-supported and basket-free:
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MTR 45 (this product) (~MERV 11): 45% dust spot efficiency. For mid-efficiency commercial and prefilter applications.
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MTR 85 (~MERV 13): 85% dust spot efficiency. For high-IAQ commercial and healthcare facilities.
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MTR 95 (~MERV 14): 95% dust spot efficiency. For pharmaceutical, surgical, and HEPA pre-stage applications.
If your application calls for a different efficiency tier, see the matching sister product. All three Multi-Test Rigid tiers share the same rigid self-supported geometry — the difference is just which efficiency tier matches your design spec.
Other Koch cartridge filter options
If your facility has existing basket framework, Koch also offers basket-compatible cartridges:
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Multi-Test Cartridge: Collapsible cartridges designed for Farr HP basket framework. Four efficiency tiers (MT 20/50, MT 50/60, MT 80/90, MT 90/95).
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Duo-Cap: Cartridge filters for Cambridge Hi-Cap and Side-Cap basket framework. MERV 8 in 1-Ply and 2-Ply construction.
Match the cartridge family to the framework already installed in your equipment. The Multi-Test Rigid is the right pick when no basket framework is available or desired.
Sizing and ordering notes
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Specify both face dimensions and depth. Cartridges are sized as Width x Height x Depth (e.g., 24x24x12). Match all three dimensions to your housing — rigid cartridges cannot be cut or trimmed in the field.
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Limited stock sizes. Multi-Test Rigid cartridges are typically build-to-order due to their specialty applications and rigid construction. Many sizes ship as quoted orders rather than from stock.
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"Call for Quote" sizes: Most Multi-Test Rigid sizes are catalog items but require direct quoting due to lower order volume or build-to-order production. These appear unavailable in the dropdown — request a quote for these sizes or for facility-scale orders.
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Heavy shipping weight. Rigid cartridges weigh substantially more than collapsible alternatives (15-34 lbs each). Shipping rates reflect actual carrier weight.
