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7.How to Select Low-Pressure, Medium-Pressure, and High-Vacuum Dust Collectors?Complete Guide to Airflow, Static Pressure, Applications, and Engineering Differences (2025 Edition)

1｜Key Terms and Ranges

  • Static Pressure (Pa / mmAq / kPa): Required pressure to overcome system resistance.
    Conversion: 1 mmAq ≈ 9.81 Pa; 1 in.wg ≈ 249 Pa ≈ 25.4 mmAq.

  • Air Volume (Q, CMM = m³/min): Air handling capacity per minute.

  • ΔP (Pressure Drop): Differential pressure across filter chambers; used to trigger cleaning and determine filter replacement.

  • Equivalent Distance (Leq): Horizontal + (Vertical × factor) + elbows/branches; used for pressure loss estimation.

Common Industrial Ranges (Starting Point for Selection):

Category

Static Pressure (approx.)

Typical Airflow per Point

Low Pressure (HVLP)

0.5–3 kPa (50–300 mmAq)

10–80+ CMM/point

Medium Pressure

3–10 kPa (300–1000 mmAq)

4–30 CMM/point

High Vacuum

10–40 kPa (1000–4000 mmAq)

1–10 CMM/point

Rule of Thumb:

  • Large airflow → Low Pressure (HVLP)

  • Long piping, high suction force → High Vacuum

  • Complex piping or mid-range needs → Medium Pressure

2｜Engineering Differences, Pros & Cons

2.1 Low Pressure (High-Volume, Low-Pressure – HVLP)

Applications: Large hoods, open operations, high dust load but not ultra-fine.

  • ✅ Pros: Energy efficient (low pressure head), simple design, easy maintenance.

  • ❌ Limitations: Requires larger ducts; loses efficiency over long distances or many elbows.

  • Duct Velocity: General powders 14–18 m/s; metal dust 18–22 m/s.

2.2 Medium Pressure

Applications: Mid-distance, multiple bends/hoses, machine enclosures, space-limited retrofits.

  • Pros: Smaller duct size, high flexibility, ideal for production line upgrades.

  • Limitations: Higher energy consumption; requires stronger fans and precise cleaning strategies.

  • Duct Velocity: 16–22 m/s depending on dust type.

2.3 High Vacuum (Central Vacuum / Tool Extraction)

Applications: Long hoses (>10–30 m), multi-floor systems, tool-mounted extraction, cleanup, precious dust recovery.

  • Pros: Strong suction, long-distance capability, central system can serve multiple points.

  • Limitations: Higher energy consumption, louder noise, requires premium filtration and sealing; combustible dust requires isolation/venting/suppression.

  • Filtration: High-vacuum filters + HEPA H13/H14 for cleanroom/indoor recirculation.

  • Vacuum Source: Roots, multi-stage centrifugal, claw-type, side-channel depending on flow-pressure curve.

3｜How to Define the Right “Operating Point”

  • The intersection of fan curve and system curve defines the operating point.

Airflow Calculation (at source):

Q(CMM)=Vf(m/s)×A(m2)×60Q (CMM) = V_f (m/s) × A (m²) × 60Q(CMM)=Vf​(m/s)×A(m2)×60

  • Weighing/charging hoods: 0.5–0.8 m/s face velocity.

  • Grinding/cutting: Adjust based on dust energy.

Equivalent Distance Estimation:

Leq≈LH+(2–3)×LV+Σ(elbows/branches)Leq ≈ L_H + (2–3) × L_V + Σ(elbows/branches)Leq≈LH​+(2–3)×LV​+Σ(elbows/branches)

Power Concept:
Higher static pressure × higher airflow = higher OPEX.
➡ Use VFD + ΔP control to optimize energy.

4｜6 Signs You Chose the Wrong Pressure System

  1. High vacuum but low airflow → Duct too small or high resistance.

  2. ΔP keeps rising, filters blind → A/C too high, wrong media, or dust peaks.

  3. Long hoses with poor suction → Need High Vacuum or shorten ducting.

  4. Using high vacuum for large hood → Poor capture efficiency.

  5. Excessive energy bills → Wrong pressure class or poor duct design.

  6. Dust leakage/odor → Wrong HEPA position, poor sealing, or air recirculation setup.

5｜Application Reference Table

Industry / Scenario

Pollutant

Distance / Network

Recommended System

Airflow per Point

Filtration / Safety

Woodworking

Sawdust / chips

Short-mid, open hood

Low Pressure

20–80 CMM

Bag / Cartridge, spark isolation

Metal Grinding

Heavy dust + sparks

Mid, many bends

Medium Pressure

8–30 CMM

Cartridge + spark arrestor, possible HEPA

Semiconductor / Electronics

Fine dust (<5 µm)

Mid, cleanroom

Medium → HEPA

8–20 CMM

ePTFE cartridge + H13/H14 HEPA, ESD safe

Food / Pharma Powders

Fine sticky dust

Long hose, multi-floor

High Vacuum

2–8 CMM

High-vacuum filter + HEPA, ESD/explosion-proof

Central Cleaning / Recovery

Mixed powders

Long network, multi-station

High Vacuum

1–6 CMM

Isolation valve + venting, wear-resistant piping

Welding Fumes / Mist

Fine particles

Large hood, extraction arm

Low–Medium Pressure

10–30 CMM

Cartridge + secondary filter, noise control

6｜Filter Media and A/C Matching

  • Low Pressure: Bag or cartridge; for fine/sticky dust → ePTFE/nano membrane + hydrophobic/oil-repellent.

  • Medium Pressure: High-efficiency cartridge / pleated bag; use inlet deflectors + pre-separation.

  • High Vacuum: High-pressure cartridges, reinforced end-caps, HEPA as final stage.

ΔP Reference:

  • Initial: 600–900 Pa → Normal: 1000–1500 Pa → Alert: ≥1700 Pa → Intervention: ≥2000 Pa.

7｜Safety: ESD / Explosion Protection / HEPA

  • Combustible Dust: Conductive hoses & filter media, grounding, equipotential bonding, isolation valves, explosion venting/suppression.

  • HEPA: For indoor recirculation / sensitive applications → H13/H14 after fan; validated by PAO/DOP test.

  • Spark / Hot Particles: Spark detection, extinguishing, or water curtain pre-treatment.

  • Noise Control: Silencers, acoustic enclosures, vibration isolation.

8｜Case Study – Choosing the Right Pressure Class

Scenario: Four weighing stations + one charging hood, simultaneity factor 0.7. Medium distance, many elbows, fine/sticky dust.

  • Airflow: 4 × (0.6 × 0.5 m × 0.6 m/s × 60) = 43.2 CMM + 18 CMM = 61.2 CMM.
    After simultaneity factor (0.7) → 42.8 CMM.
    Add 20% margin → 51.4 CMM.

  • Network Resistance: High due to elbows/hoses → Medium Pressure chosen.

  • Filtration: ePTFE cartridge, ΔP-triggered cleaning, optional HEPA.

  • Safety: Anti-static media, full grounding, isolation venting if combustible.

9｜Common FAQs

  • Q1: Only 1–2 points, short distance – do I need High Vacuum?
    → Usually not. Low Pressure is more energy efficient.

  • Q2: Is High Vacuum always better?
    → No. High vacuum = high pressure, low airflow, high noise/energy. Not ideal for large hoods.

  • Q3: When should I upgrade to Medium Pressure?
    → When long hoses/elbows reduce airflow too much, or local capture speed must be higher.

  • Q4: Do I need HEPA?
    → Yes for fine dust, indoor recirculation, cleanrooms, or sensitive products (H13/H14 + PAO/DOP test).

  • Q5: Which pressure system is best for combustible dust?
    → Depends on the process, not pressure class. All systems must use anti-static media, grounding, explosion venting/suppression.

10｜Selection Checklist (RFQ Template)

  • Inlets: Size, face velocity, simultaneity, estimated airflow (CMM).

  • Ducting: Horizontal/vertical length, elbows, flexible hoses, floors.

  • Dust Properties: Particle size, stickiness, oil/moisture, abrasiveness, combustibility (Kst/MIE).

  • Site Conditions: Indoor/outdoor, noise limits, space/power, recirculation needs.

  • Filtration: Media (ePTFE, anti-static, hydrophobic), HEPA requirement.

  • Control: ΔP-triggered cleaning, VFD, monitoring & alarms.

  • Safety: Grounding, spark detection, flame isolation, explosion venting/suppression.

  • Acceptance (SAT): Airflow, ΔP, leakage, noise, HEPA integrity, runtime.

  • TCO: Energy, consumables, spare parts, SLA/warranty.

11｜Common Pitfalls (Mistakes to Avoid)

  • Choosing by motor horsepower, ignoring fan/system curves.

  • Using high vacuum for large hoods → poor capture efficiency.

  • Ignoring worst-case branch resistance → commissioning failures.

  • Wrong filter media for sticky/fine dust → runaway ΔP.

  • High vacuum without explosion venting/grounding.

  • No ΔP baseline, alarm levels, or inspection protocol → reactive maintenance only.