Technical White Paper

HAF Filter
Technology

High Air Flow Electrostatic Filtration for Professional Dehumidifiers
"The Science Behind Maximum Performance with Minimum Pressure Drop"
Published ByDeli Filtration Research Lab
Version2.0 | June 2026
ClassificationTechnical Reference Document

Inhaltsverzeichnis

  • Executive Summary§2
  • Chapter 1: Understanding LGR Dehumidifier Challenges§3
  • 1.1 The Water Damage Restoration Workflow
  • 1.2 Why Air Filtration Matters in Dehumidification
  • 1.3 Traditional Filter Limitations
  • Chapter 2: HAF Technology Explained§5
  • 2.1 What is "High Air Flow"?
  • 2.2 Electrostatic Capture Mechanism
  • 2.3 Material Science: Microstructured Media
  • 2.4 Anti-Microbial Surface Treatment
  • Chapter 3: Performance Advantages§8
  • 3.1 Airflow Retention Over Dust Loading
  • 3.2 Particle Capture Efficiency (MERV 8–11)
  • 3.3 Energy Cost Savings
  • 3.4 Filter Lifespan & TCO Analysis
  • Chapter 4: Application Guide§11
  • 4.1 Compatible Equipment
  • 4.2 Installation Best Practices
  • 4.3 Maintenance Protocol: Why NOT to Wash
  • Chapter 5: Deli HAF Filter Specifications§13
  • 5.1 Technical Data Sheet
  • 5.2 Test Results & Certifications
  • 5.3 Customization Options
  • Chapter 6: Case Studies§15
  • Appendices A–C§16
Executive Summary

Übersicht & Kernergebnisse

In professional water damage restoration, dehumidifier performance directly impacts project timelines and profitability. HAF (High Air Flow) filters represent a breakthrough in balancing two critical — and often competing — requirements: high particle capture efficiency to protect compressor and coils, and minimal airflow restriction to maintain CFM throughout service life.

Was dieses White Paper abdeckt

  • How electrostatic capture works at the molecular and fiber level
  • Why traditional pleated filters fail in LGR applications
  • Quantified airflow retention advantage: HAF vs. MERV 11/13
  • 3-year total cost of ownership (TCO) analysis
  • Proper selection, installation, and maintenance protocols
  • Compatible equipment guide: Dri-Eaz LGR 700, Phoenix, AlorAir, and others
>85%
Airflow retained after 500 hours of operation (vs. 52% for MERV 11)
65–92%
Particle capture efficiency across 0.3–10 μm range (MERV 8–11 equivalent)
12–18%
Energy cost reduction vs. MERV 13 at equivalent operating hours
$107
3-year TCO savings per dehumidifier vs. MERV 13 (filter + labor + energy)

About Deli: 30+ years manufacturing air filtration products for Gree Electric, Freudenberg, Philips, and customers in 50+ countries. ISO 9001:2015 certified since 2005. 53 granted patents. Bureau Veritas Re-Audit PASS, November 2025.

Chapter 1

LGR-Entfeuchter-Herausforderungen verstehen

1.1 Der Arbeitsablauf der Wasserschadensanierung

Water damage restoration — from floods, pipe bursts, hurricanes, and HVAC failures — follows a time-critical 4-phase protocol that determines both project outcomes and insurer liability:

  • Phase 1: Assessment (0–4 hours) — Moisture mapping, category classification (Cat 1–3), scope documentation
  • Phase 2: Water Extraction (4–24 hours) — Submersible pumps, truck-mounted extractors, wet vacuums
  • Phase 3: Dehumidification (24–120 hours) — LGR dehumidifiers, air movers, drying chambers (critical phase)
  • Phase 4: Verification & Monitoring — Moisture readings, documentation, handoff

During Phase 3, LGR (Low-Grain Refrigerant) dehumidifiers must remove moisture to below 40% RH within 72–96 hours while operating continuously in contaminated environments. A single LGR unit typically moves 250–700 CFM depending on model — and that airflow must be maintained throughout the drying cycle.

1.2 Warum Luftfiltration bei der Entfeuchtung wichtig ist

Post-water-damage environments contain elevated concentrations of airborne particulates that standard residential HVAC systems are not designed to handle:

Typical Airborne Contaminant Concentrations — Active Water Damage Site
Dust & Drywall Particles1,200–5,000 μg/m³
Drywall / Construction Dust
Mold Spores500–2,500 μg/m³
Mold Spores (2–10 μm)
General Dust & Debris800–3,000 μg/m³
General Airborne Dust
Bacterial Aerosols (Cat 2/3)300–900 μg/m³
Bacterial Aerosols
Data represents typical Category 2–3 water damage environments per IICRC S500 guidelines.

Without effective filtration, dehumidifiers operating in these environments suffer compressor contamination leading to equipment failure; coil fouling causing 30–40% efficiency loss; cross-contamination and health hazards for restoration personnel; and frequent breakdowns that extend project timelines and increase insurer costs.

1.3 Einschränkungen herkömmlicher Filter

Restoration professionals have historically attempted to use standard HVAC filters in LGR dehumidifiers — with predictable results. Each common filter type fails in a specific way:

Filter TypeInitial Pressure Drop500-hr Pressure DropCFM at 500 hrsParticle Capture
HAF Electrostatic (Deli)0.15–0.20 in. w.c.0.18–0.25 in. w.c.>85% of rated65–92% (0.3–10 μm)
MERV 13 Pleated0.35–0.50 in. w.c.0.80–1.20 in. w.c.~52% of rated85–95%
MERV 8 Pleated0.18–0.30 in. w.c.0.40–0.65 in. w.c.~70% of rated40–70%
Basic Foam0.08–0.15 in. w.c.0.25–0.50 in. w.c.~78% of rated<25% (no electrostatic)
Fiberglass Panel0.04–0.08 in. w.c.0.20–0.45 in. w.c.~80% of rated<15% (coarse only)

Key Insight: A MERV 13 filter starts with acceptable efficiency but reaches unacceptable pressure drop within 200–300 hours — exactly the range when a restoration project is in its critical drying phase. HAF maintains rated airflow across the entire service life.

Chapter 2

HAF-Technologie erklärt

2.1 Was bedeutet "High Air Flow"?

HAF (High Air Flow) is a designation for filter media engineered through three structural principles that together maintain rated CFM throughout the filter's service life:

  1. Open Channel Architecture: 60–70% void space (compared to 40% in standard pleated filters) allows dust to load progressively without causing rapid surface blockage.
  2. Gradient Density Structure: Coarse fibers at the inlet face capture large particles (>10 μm); progressively finer fibers toward the outlet capture smaller particles without concentrating the dust load on one surface.
  3. Low Initial Pressure Drop: 0.15–0.25 inches w.c. at 500 FPM face velocity, compared to 0.40–0.60 inches for MERV 13 — giving the filter a performance advantage that persists even as it loads with dust.

2.2 Elektrostatischer Abscheidemechanismus

HAF filter media is electrostatically charged during manufacturing via corona discharge — a high-voltage process that permanently aligns electrical dipoles within the polypropylene/polyester fiber matrix. This charge creates a secondary capture mechanism that is entirely separate from mechanical filtration:

Capture MechanismHow It WorksParticle Size RangeEffectiveness
Electrostatic (coulombic)Charged fiber attracts oppositely-charged particles0.3–3.0 μmHigh
Inertial impactionLarge particles cannot follow airstream curves>5 μmHigh
InterceptionParticle contacts fiber while following streamline1–5 μmMedium
Diffusion (Brownian)Random particle motion causes contact<0.3 μmLow (not HAF's design target)

⚠️ Critical: Water exposure neutralizes the electrostatic charge permanently. A washed HAF filter loses 60–80% of its particle capture efficiency in the <3 μm range. HAF filters must never be washed or subjected to liquid cleaning.

2.3 Materialwissenschaft: Das mikrostrukturierte Medium

Deli HAF filters use a polypropylene (PP) / polyester (PET) blend optimized for the specific demands of LGR dehumidifier environments:

Spezifikationen des Filtermaterials

Fiber Diameter
5–25 micrometers
Basis Weight
80–120 g/m²
Media Thickness
10–25 mm (customizable)
Tensile Strength
>15 N/cm
Electrostatic Charge Stability
>24 months
Void Space
60–70% open channel
Temperature Rating
Up to 60°C continuous
Humidity Rating
Up to 100% RH (no washing)

Manufacturing follows a 4-stage process: (1) Meltblown extrusion creates the fine-diameter fiber matrix; (2) Corona discharge charging adds the electrostatic capture mechanism; (3) Antimicrobial treatment is applied to the fiber surface; (4) Multi-layer compression optimizes the density gradient from inlet to outlet face.

2.4 Antimikrobielle Oberflächenbehandlung

All Deli HAF filters incorporate an antimicrobial surface treatment applied during manufacturing. In water damage restoration environments — where mold spore concentrations can reach 2,500 μg/m³ — a filter without antimicrobial protection can itself become a source of microbial growth and odor within 48–72 hours of continuous operation.

Test StandardOrganism TestedResultStatus
ASTM G21Mold (Aspergillus, Penicillium)No growth after 28 daysPASS
ISO 846Bacteria (E. coli, S. aureus)>99.9% inhibitionPASS
Service LifeAll organismsEffective for filter service life (500–700 hours)CERTIFIED
SafetyVOC emissionsNon-detectable — no VOC off-gassingCOMPLIANT
Chapter 3

Performance-Vorteile

3.1 Luftstromerhaltung bei Staubbeladung

The most critical performance differentiator for LGR applications is airflow maintenance under progressive dust loading. The following data reflects ASHRAE 52.2 test methodology at 500 FPM face velocity:

       Airflow Retention (% of Initial CFM) vs. Operating Hours
       Test Condition: 500 FPM | ASHRAE 52.2 | Synthetic Dust Load

100% ┤━━━━━━━━ Deli HAF Electrostatic ━━━━━━━━━━━━━━━━━━━━━━━━ 87%
     │
 90% ┤
     │
 80% ┤ ╲━━━━━━ MERV 11 Pleated ━━━━╲
 70% ┤                              ╲━━━━━━━━━━╲
 60% ┤                                            
 52% ┤                                              ━━━━━━━━
 45% ┤ ╲━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ MERV 13 ━━
     └────┴────┴────┴────┴────┴────┴────┴────┴────┴────
     0   100  200  300  400  500  600  700  800  900  1000
                        Operating Hours

Operational Impact: At 500 hours, HAF maintains 87% airflow vs. 52% for MERV 11 and 45% for MERV 13. In a restoration context, this translates to approximately 22% faster structural drying — directly reducing project duration and labor cost.

3.2 Partikelabscheidegrad (MERV 8–11)

HAF is not a high-efficiency filter across all particle sizes — it is optimally designed for the 1.0–10 μm range, which covers the primary biological and construction contaminants found in water damage environments:

Particle SizeHAF (Deli)MERV 13 PleatedFoam FilterTypical Contaminant
0.3–1.0 μm55–65%80–90%<10%Bacteria, smoke
1.0–3.0 μm70–80%85–95%15–25%Mold spores, fine dust
3.0–10.0 μm85–92%>95%40–60%Mold, drywall, pollen
>10.0 μm>95%>98%80–90%Coarse dust, hair

The trade-off is intentional and engineered: HAF sacrifices approximately 15–25% efficiency in the sub-micron range (<1 μm) to achieve the open-channel structure that maintains airflow. For LGR dehumidification — where rated CFM is the primary performance driver — this is the correct engineering trade-off. HEPA-equivalent filtration at LGR airflow volumes would collapse a dehumidifier's moisture removal rate within 50–100 hours of operation.

3.3 Energiekosteneinsparungen

Lower pressure drop translates directly to reduced motor power consumption. The calculation below uses a standard LGR 700-class dehumidifier (1.5 HP fan motor):

Scenario A — Standard MERV 13 Pleated

Operating hours/year (fleet)500 hrs/unit
Average pressure drop0.55 in. w.c.
Average power consumption1,250 W
Electricity rate$0.12/kWh
Annual energy cost/unit$75.00

Scenario B — Deli HAF Electrostatic

Operating hours/year (fleet)500 hrs/unit
Average pressure drop0.18 in. w.c.
Average power consumption1,050 W
Electricity rate$0.12/kWh
Annual energy cost/unit$63.00
Annual savings per unit: $12  |  Fleet of 50 units: $600/year

3.4 Filterlebensdauer & TCO-Analyse

A 3-year total cost of ownership (TCO) analysis per dehumidifier unit, factoring filter cost, labor for replacement, and energy differential:

Cost ItemHAF (Deli)MERV 13 PleatedBasic Foam
Filter unit cost (direct)$18–25$15–22$5–8
Replacements per year2× (every 250 hrs)4× (every 125 hrs)6× (every 80 hrs)
3-year filter cost$108–150$180–264$90–144
Replacement labor (3 yr)$80 (6 changes)$160 (12 changes)$240 (18 changes)
Energy cost differential (3 yr)Baseline+$36+$60 (higher drop loaded)
Equipment downtime riskLowMedium (coil fouling)High (no micro-capture)
3-Year TCO (midpoint)$317$438$534
Savings vs. MERV 13$121 per unit
Chapter 4

Anwendungsleitfaden

4.1 Kompatible Ausrüstung

Deli HAF filters are manufactured to OEM-equivalent dimensions for all major LGR dehumidifier brands:

Equipment BrandModelsDeli Filter SKUFilter Dimensions
Dri-EazLGR 700, LGR 2800i, LGR 3500iDL-HAF-DRIEAZ700Custom to model spec
PhoenixR200S, R200C, TriumphDL-HAF-PHX200SCustom to model spec
AlorAirStorm SLGR 1600X, Sentinel HD55DL-HAF-ALOAIR160Custom to model spec
Dri-EazPhoenix LGR (LGR 2000)DL-HAF-PHXLGRCustom to model spec
Dri-EazDri-Pod, F203DL-HAF-DRIPODCustom to model spec
CustomNon-standard dimensionsDL-HAF-CUSTOMOEM spec — contact us

4.2 Best Practices für die Installation

  1. Pre-installation inspection: Confirm filter dimensions match housing spec to ±1 mm. An improperly sized filter allows bypass airflow around the edges, reducing effective capture efficiency by 30–60%.
  2. Housing inspection: Clean the filter housing with a dry cloth or compressed air before installing a new filter. Mineral deposits or debris in the housing can damage the filter media on installation.
  3. Orientation: HAF filters have a defined airflow direction — the coarser face (slightly rougher texture) faces the incoming airstream (toward the fan intake). Reversed installation reduces efficiency by approximately 20%.
  4. Sealing: Ensure the filter seats flush against all four housing edges. Light finger pressure around the perimeter confirms the seal. Do not force or compress the filter — this compresses the open channels and increases pressure drop.
  5. Initial operation check: After installing a new filter, run the unit for 5 minutes and check for airflow reduction. A properly installed HAF filter should produce no noticeable airflow reduction compared to an unfiltered unit.

4.3 Wartungsprotokoll: Warum man NICHT waschen sollte

The most common field error with HAF filters is attempting to wash and reuse them. This is categorically different from humidifier wick filters (which can be lightly rinsed) — HAF filters must not be washed under any circumstances.

⚠️ Why washing permanently damages HAF filters:
The electrostatic charge that enables particle capture in the 0.3–3 μm range is held by aligned electrical dipoles in the polypropylene fiber. Water — especially with any dissolved minerals, detergent, or surfactant — permanently disrupts these dipoles. A washed HAF filter may look cleaner but has lost its primary capture mechanism for the most critical particle size range (mold spores, bacteria). Testing shows 60–80% reduction in sub-3 μm capture efficiency after a single washing.

Correct field protocol when a filter appears heavily loaded:

  • Remove filter from housing
  • Tap gently against a solid surface 2–3 times to dislodge loose surface debris (outside only)
  • Inspect for structural integrity — if media is torn, compressed, or deformed, replace immediately
  • If airflow from the unit has not recovered (<85% of baseline), replace the filter
  • Never use compressed air directly into the filter face — this embeds debris deeper into the media
Chapter 5

Deli HAF-Filterspezifikationen

5.1 Technisches Datenblatt

Standard HAF-Filter — Technisches Datenblatt (TDS-HAF-2026)

Filter Type
HAF Open-Channel Electrostatic
Media Material
PP/PET Electrostatically Charged
MERV Equivalent
MERV 8–11 (size-dependent)
Initial Pressure Drop
0.08–0.15 in. w.c. @ 250 CFM
Airflow Retention (500 hrs)
>85% of rated CFM
Service Life
500–700 operating hours
Antimicrobial
Standard (ASTM G21 PASS)
Temperature Range
-10°C to +60°C
Humidity Range
0–100% RH (no liquid contact)
Frame Material
Cardboard / Aluminum (custom)
MOQ
300–500 units
Sample Lead Time
7 business days

5.2 Testergebnisse & Zertifizierungen

Certification / TestStandardResultCertificate Holder
Quality Management SystemISO 9001:2015Certified since 2005Nantong Deli
Environmental ManagementISO 14001:2015CertifiedNantong Deli
Factory Audit — ManufacturingBureau VeritasRe-Audit PASS (Nov 2025)MIC-ASR2541690
Mold ResistanceASTM G21No growth / 28 daysOn file
Bacterial InhibitionISO 846>99.9% inhibitionOn file
Hazardous SubstanceRoHS / REACHCompliantNantong Deli
MEI Award 2025Made Excellence InnovationWinner — Industrial Equipmentmeiawards.com

5.3 Anpassungsoptionen

All Deli HAF filters are available in custom configurations for OEM and private-label buyers:

  • Custom dimensions: Any length × width × thickness within manufacturing capability (contact for feasibility). Dimensional tolerance ±0.5–1.0 mm.
  • Media density: Multiple density grades available — select lighter media for maximum airflow (MERV 8 equiv.) or denser media for higher efficiency (MERV 11 equiv.)
  • Frame material: Standard cardboard frame; aluminum frame available for high-humidity environments; frameless roll stock for custom integration
  • Private label: Custom printing on frame/packaging; your brand name and part numbers
  • Bulk packaging: Individual poly bags, multi-pack retail boxes, or bulk carton
Chapter 6

Fallstudien

Case A

Hurrikan-Aufräumarbeiten — Florida, USA

Situation: A regional restoration company deployed 32 Dri-Eaz LGR 700 units following a Category 2 hurricane event affecting 14 residential and 3 commercial properties. Previous seasons had used MERV 8 pleated filters, resulting in multiple compressor failures mid-project.

Solution: Switched fleet to Deli HAF DL-HAF-DRIEAZ700 filters. Replacement schedule maintained at 250 operating hours per filter (vs. previous 80-hour schedule with foam filters).

Results (8-week operation):

0
Compressor failures during project
31%
Reduction in filter replacement labor
$2,100
Estimated cost savings vs. prior-season approach
19%
Faster average drying cycle (maintained CFM)
Case B

Wasserschaden in Gewerbegebäuden — Vereinigtes Königreich

Situation: A 3,200 m² commercial office building suffered a burst pipe affecting 4 floors. The restoration contractor used 18 Phoenix R200S units and initially attempted MERV 13 filters to meet indoor air quality documentation requirements. Within 96 hours, 6 units showed significantly reduced airflow output.

Solution: Switched to Deli HAF DL-HAF-PHX200S at the 96-hour mark. Deli provided material data sheets satisfying the contractor's insurer documentation requirement for antimicrobial treatment and particle capture range.

Results:

100%
Units restored to rated airflow within 2 hours
72 hrs
Time saved on overall project timeline
£3,400
Estimated labor cost saving from faster drying
Appendix A

Zusammenfassung der vergleichenden Testdaten

ParameterHAF (Deli)MERV 13MERV 8FoamTest Standard
Initial ΔP (in. w.c.)0.08–0.150.35–0.500.18–0.300.05–0.12ASHRAE 52.2
ΔP at 500 hrs0.18–0.250.80–1.200.40–0.650.25–0.50ASHRAE 52.2
CFM retention @ 500 hrs>85%~45%~70%~78%Calculated
Efficiency 1–3 μm70–80%85–95%50–65%15–25%ASHRAE 52.2
Efficiency 3–10 μm85–92%>95%70–80%40–60%ASHRAE 52.2
AntimicrobialStandardOptionalOptionalNoneASTM G21
Washable?NoNoSomeYes
Typical service life500–700 hrs200–300 hrs300–400 hrs80–120 hrsField data
Appendix B

Glossar

CFM: Cubic Feet per Minute — volume of air moved by a fan or dehumidifier per unit time. LGR dehumidifiers typically operate at 250–700 CFM depending on model size.

Corona Discharge: High-voltage electrical process used during HAF filter manufacturing to permanently charge polypropylene fibers, enabling electrostatic particle capture.

FPM: Feet per Minute — face velocity of air through a filter. Test standard 500 FPM is used in ASHRAE 52.2 filter efficiency testing.

HAF: High Air Flow — filter media designation for electrostatic open-channel filters engineered to maintain rated CFM throughout service life.

LGR: Low-Grain Refrigerant — dehumidifier technology that pre-cools incoming air to remove additional moisture before it reaches the evaporator coil. LGR units deliver higher pints-per-day output than conventional refrigerant dehumidifiers.

MERV: Minimum Efficiency Reporting Value — ASHRAE standard 52.2 filter efficiency rating scale from 1 to 16. Higher MERV = finer particle capture but higher pressure drop.

Pressure Drop (ΔP): Reduction in air pressure across a filter caused by flow resistance. Measured in inches of water column (in. w.c.) or Pascals. Higher ΔP = more motor work required to maintain airflow.

TCO: Total Cost of Ownership — lifecycle cost analysis including product cost, labor, energy, and downtime over a defined period.

Appendix C

Kontakt- & Bestellinformationen

Nantong Deli Purification Equipment Co., Ltd.
Nantong, Jiangsu Province, China
Website: ntdeli.top/haf-dehumidifier-filter
Email: amanda@ntdeli.top
WhatsApp: +86 138 6296 0263
MOQ: 300–500 units (standard) | Custom dimensions negotiable
Sample Lead Time: 7 business days
Production Lead Time: 15–30 days after order confirmation

To request a quote or technical consultation:
Send your dehumidifier model number and annual volume to amanda@ntdeli.top. Include "HAF White Paper Inquiry" in the subject line for priority routing. Full technical data sheets, material safety data sheets, ISO certificates, and Bureau Veritas audit report (MIC-ASR2541690) available upon request.

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