SECTION 600-DEFINITIONS
Abrasion Resistance
The ability of a fiber or fabric (media) to withstand surface wears.
ACFM
Actual cubic feet of gas per minute. The volume of gas flowing per minute at the operating temperature,
pressure, elevation and composition.
Air-to-Cloth Ratio
The ratio between ACFM flowing through a dust collector and the square feet of filter area available
(ACFM/Ft
2
). Sometimes referred to as the velocity of air through the cloth.
Blinding
Blockage in a fabric or media by dust that cannot be discharged by the cleaning mechanism, resulting in
a reduced gas flow and an increased pressure drop across the media. Once enough material has built
up, airflow is severely restricted and the bags have to be cleaned or replaced.
Bridging
Material handling problem characterized by the particulate forming a cavity over the discharge or
opening of a hopper or storage vessel. Also, the accumulation of collected dust between two or more
filter elements.
Can Velocity
In a dust collector with the filter elements suspended from the tubesheet, "can velocity" is the upward air
stream speed calculated by dividing the open cross sectional area of the dust collector (less the area of
the filter bottom) into the full volume of the exhaust fan (ACFM/Ft
2
= Feet per Minute),
Ref. Interstitial
Velocity.
Clean Air Plenum
The dust collector area, through which gases are directed, located on the clean side of the filter media.
Collection Efficiency
The measure of a dust collector's ability to remove particulate from the inlet gas, typically expressed in
percent or emission rate (grains per cubic foot).
Dewpoint
The temperature at which condensation begins to form as the gas is cooled.
Diaphragm Valve
A compressed air valve operated by a solenoid valve that opens to allow a pulse to a row of filters.
Differential Pressure
The change in pressure or the pressure drop across a device. The difference between static pressures
measured at the inlet and outlet of a device,
Ref. Pressure Drop.
Dust Cake
A dust build-up on the filter elements that increases the efficiency of the filter media.
Dust Loading
The weight of solid particulate suspended in an air stream, usually expressed in grains per cubic foot (or
grams per cubic meter).
Emissions
Particulate that escapes through or around a dust collector into the atmosphere.
68
Fan
