This guide summarizes extended-surface pleated filters commonly used as prefilters or stand-alone solutions in commercial and industrial HVAC systems. It consolidates features, performance ranges, sizes, and selection tips for MERV 8, MERV 9, and MERV 10 families in 1", 2", and 4" depths, with standard and high-capacity options.
Quick Compare
Filter Family |
Typical Use |
Depths |
Capacity Options |
Representative Initial ΔP* |
Recommended Final |
MERV 8 / 8A |
Robust prefilter; high dust loading; harsh environments |
2", 4" (some 1") |
Standard & High Capacity |
~0.18–0.26" w.g. @ 375–500 fpm (24×24) |
~1.0–1.5" w.g. |
MERV 9 / 9A |
Long-life pleat; prefilter or stand-alone in cleaner systems |
1", 2", 4" |
Standard & High Capacity variants |
~0.20–0.37" w.g. @ common flows (size & depth dependent) |
~1.0–1.5" w.g. |
MERV 10 |
Upgrade from lower-efficiency pleats; finer particle removal |
1", 2", 4" |
Standard & High Capacity |
~0.18–0.29" w.g. @ 500 fpm (2–4"); ~0.20–0.24" (1") |
~1.0–1.5" w.g. |
* Representative values vary by size, depth, and capacity; see snapshots below.
Construction & Materials
- Media: 100% synthetic, mechanical (non-electret) fibers; progressive density design helps maximize dust-holding capacity (DHC) while limiting pressure rise. Media is non-shedding and moisture-resistant and does not support microbial growth.
- Support: Expanded metal backing on air-exit side to stabilize pleats and prevent flutter; some heavy-duty lines use thicker wire backing and optional internal reinforcement for abusive or high-velocity applications.
- Frame: Moisture-resistant beverage-board or similar die-cut frame with diagonal/cross members to lock pleats; optional “extra-tough” designs add heavier board and reinforcement.
- Form factor: 1", 2", and 4" depths; standard and high-capacity (more media area/pleats per foot) variants to lower resistance and extend service life.
- Ratings/Standards: Tested to ASHRAE 52.2 (some with Appendix J reporting); UL 900 classified. Typical continuous temperature ratings up to ~180–200 °F (varies by model and frame).
Common Sizes & Depths
Pleated filters are available in a full spread of nominal sizes, typically in 1", 2", and 4" depths. Examples include:
- 1" depth: Common from 10×10 to 24×24, plus wides (e.g., 20×30). Rated flow points often ~300 fpm nominal; some long-life 1" constructions list performance at higher flows for 24×24.
- 2" depth: Broadest size coverage (e.g., 12×20, 16×25, 20×24, 24×24, 20×30). Rated at ~500 fpm nominal; high-capacity variants add significant media area.
- 4" depth: Similar coverage to 2"; deeper pleat pack improves DHC and stability. Some lines use reinforced or double-wall frame structures for durability.
Selection & Application Notes
- Efficiency target: Choose MERV 10 for finer particle removal when upgrading from lower MERV; MERV 8/9 for rugged prefiltration or high dust loading applications.
- Capacity choice: High-capacity (HC) builds increase media area and reduce initial resistance—useful where energy savings or longer service intervals are priorities.
- Final resistance: Size and maintain to ~1.0–1.5" w.g. final (follow equipment limits). Higher ΔP increases fan energy and can drive bypass or frame deflection in lighter builds.
- Environment: Synthetic, moisture-resistant media are preferred for humid or intermittent wet conditions; heavy-duty frames/backing help in high-velocity or abrasive environments.
- Fit & sealing: Verify actual vs. nominal dimensions and housing tolerances. Proper gasketing and square installation reduce bypass and preserve rated performance.
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