What is air-to-cloth ratio in a baghouse?

Air-to-cloth ratio (A/C) is the airflow loading on filter media, calculated as ACFM divided by total filter cloth area. It is commonly expressed as feet per minute (FPM) and helps guide preliminary sizing and performance checks.

What is interstitial velocity and why does it matter?

Interstitial velocity is the air speed in the spaces between filter bags. If it is too high, pulsed dust can remain suspended and be re-entrained, leading to unstable differential pressure and poor hopper drop-out.

What is can velocity in a baghouse?

Can velocity is the vertical gas velocity in the lower plenum of the baghouse. Higher can velocity can keep dust suspended, reduce drop-out to the hopper, and increase wear or re-entrainment risk.

How do you calculate total filter cloth area for bag filters?

Total cloth area is calculated from bag geometry and quantity. For round bags, a common estimate is (π × bag diameter × bag length × number of bags) divided by 144 to convert from square inches to square feet.

How do you estimate leak testing powder quantity?

A quick field estimate is powder (lb) = total fabric area (sq ft) ÷ 1,000. Actual dosage may vary based on method, distribution, and acceptance criteria.

How do you estimate precoating powder quantity?

A quick estimate is powder (lb) = cloth area (sq ft) × 0.042. Precoating helps form a stable dust cake and can reduce blinding for fine or sticky dust.

How do you calculate duct air velocity from CFM and duct diameter?

Duct air velocity (FPM) is calculated as CFM divided by duct cross-sectional area (sq ft). For round duct, area = π × (D/24)^2 where D is diameter in inches.

How do you calculate duct diameter from CFM and target velocity?

First compute required area as Area (sq ft) = CFM ÷ FPM. For a round duct, diameter in inches is D = 24 × √(Area/π). Final duct design should also consider layout, elbows/branches, pressure losses, and abrasion.

Baghouse System Design Calculators | Air-to-Cloth, Duct Velocity & Duct Size (CFM/FPM)

Baghouse Design & Troubleshooting Tools

Use these calculators as a reference for preliminary design and quick field checks. Actual performance depends on dust characteristics, moisture, temperature, cleaning system, and gas distribution.

1) Air-to-Cloth Ratio Calculator

Airflow loading on filter media: ACFM ÷ Cloth Area. Output shown in FPM and m/min.

A/C

Airflow (ACFM)

Filter Cloth Area (sq. ft.)

Air-to-Cloth Ratio

— FPM / — m/min

Formula: FPM = ACFM ÷ Area

Note: Use as a reference only—dust loading, temperature, humidity, and chemistry may require a more conservative A/C.

2) Interstitial Velocity Calculator

Air speed between bags. Helps identify re-entrainment risk and poor settling after pulsing.

Airflow (ACFM)

Number of Bags

Baghouse Side Length (inches)

Baghouse Side Width (inches)

Bag Diameter (inches)

Interstitial Velocity

— FPM

Net area = (L×W − π×(D/2)²×Bags) ÷ 144

Note: If IV is too high, pulsed dust can stay aloft and get re-captured, causing unstable DP and poor hopper drop-out.

3) Baghouse Can Velocity Calculator

Vertical gas velocity in the lower plenum (“can”). Helps prevent dust re-entrainment.

Airflow (ACFM)

Baghouse Side Length (inches)

Baghouse Side Width (inches)

Can Velocity

— FPM

Formula: ACFM ÷ ((L×W) ÷ 144)

Note: High can velocity can keep dust suspended, reducing collection efficiency and increasing wear.

4) Baghouse Filter Cloth Area Calculator

Total cloth area (all bags). Used for A/C ratio, leak testing powder, and precoating powder sizing.

Bag Diameter (inches)

Bag Length (inches)

Number of Bags

Total Filter Cloth Area

— sq ft / — m²

Formula: (π×D×L×Bags) ÷ 144

Note: Larger cloth area generally supports lower A/C ratios, lower DP, and longer bag life.

5) Leak Testing Powder Calculator

Quick estimate: Powder (lb) = Fabric Area (sq ft) ÷ 1,000.

Total Fabric Area (sq ft)

Leak Testing Powder Required

— lb / — kg

Formula: Area ÷ 1000

Note: Leak testing is a quick, low-cost way to confirm bag/seal integrity and prevent bypass emissions.

6) Precoating Powder Calculator

Quick estimate: Powder (lb) = Cloth Area × 0.042 (≈ 0.042 lb per sq ft).

Filter Cloth Area (sq ft)

Precoating Powder Required

— lb / — kg

50-lb bags (estimate): —

Rate: 0.042 lb/sq ft

Note: Precoating helps protect media from fine/sticky dust, forms a stable dust cake, and often extends bag life.

7) Air Velocity Calculator (Duct)

Duct conveying air speed: Velocity = CFM ÷ Area. Output shown in FPM.

Airflow (CFM)

Duct Diameter (inches)

Air Velocity

— FPM

Area = π×(D/24)², so FPM = CFM ÷ Area

Note: Keep duct velocity above the minimum conveying velocity for your dust to prevent settling and plugging.

8) Duct Size Calculator

Solve duct diameter from airflow & target velocity. Output shown in inches.

Airflow (CFM)

Target Velocity (FPM)

Duct Diameter

— in.

D(in) = 24×√((CFM/FPM)/π)

Note: Final duct design must consider layout, elbows/branches, static pressure, erosion, and fan capability.

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