Indutech

Baghouse Air-to-Cloth Ratio, Bag Count & Can Velocity

The ratio that sizes a baghouse is a velocity: cubic metres a minute over square metres of cloth.

Gas Design flow & target
m³/h

Actual flow at the filter temperature and pressure, not standard conditions.

m/min

What your cleaning type, dust and fabric allow, from the supplier or your own units. Pulse-jet cleaning runs higher ratios than shaker or reverse-air cleaning.

Bags & Housing From the drawing
mm
m
bags
compartments

Isolated sections cleaned one at a time. Enter 1 for an online-cleaned unit with nothing taken offline.

m²

Plan area of the bag compartment, the tube-sheet area, through which the gas rises between the bags.

Air-to-Cloth Ratio

— m/min

Gas flow per minute over the total cloth area; also the filtration velocity through the fabric

Sizing

Air-to-Cloth Ratio
— ft/min
Cloth Area per Bag
— m²
Total Cloth Area
— m²
Ratio with One Compartment Offline
— m/min
Bags Needed for the Target Ratio
— bags
Bags Short of the Target
— bags
Can Velocity between the Bags
— m/min
Free Area between the Bags
— m²
Gas Flow
— m³/min

The US EPA fact sheets for fabric filters (EPA-452/F-03-025, pulse-jet; EPA-452/F-03-026, reverse-air) define the air-to-cloth ratio as the ratio of volumetric air flow to cloth area and make it the number that sets baghouse size; its selection depends on the particulate loading and characteristics and on the cleaning method, a heavy loading needing a larger baghouse to avoid an excessive dust cake and pressure drop. Pulse-jet units clean online, row by row, and so achieve higher gas-to-cloth ratios than the compartmented types; they use felted (nonwoven) fabrics because they do not rely on a dust cake. Typical fabric filter pressure drop is 100 to 250 mm of water column (AWMA, 1992, as cited in the sheets). The target ratio here is yours: the tool prints no typical values. Cloth per bag is the cylinder wall only; pleated bags and cartridges carry more area per metre. Can velocity is the gas rising through the free area between the bags; too high and dislodged dust is carried back onto the cloth instead of falling to the hopper. **Choose the ratio from your dust and cleaning type; this sizes the cloth that delivers it.**

Baghouse Air-to-Cloth Ratio, Bag Count & Can Velocity — free, with the formula and a worked example, at Textile School.