Farr Gold Series, Installation, Operation And Maintenance Manual, Page: 69 / 76

A device for moving air and dust through a ventilation system. If the fan is on the dirty air side of the
collector, it is called a positive system. If the fan is on the clean air side of a collector, it is called a
negative system.
Filter Media
The air permeable material utilized in a dust collector, which provides a barrier to remove dust from the
airstream.
Hopper
The section of a dust collector located below the dust collector housing utilized for the accumulation and
discharge of the collected dust.
Impingement
The physical contact of a dust-laden gas flow against a filter media. Typically referred to the abrasive
wear caused by this impact.
Inches of Water
A unit of pressure equal to the pressure exerted by a column of water one inch high at standard
conditions (70
O
F @ sea level), usually expressed as inches water gauge ("w.g.) or inches water column
("w.c.).
Interstices
The openings or voids in a filter media. In addition, the openings or voids between filter elements.
Interstitial Velocity
Velocity of a gas as it passes between a compartment of filter elements calculated at its highest value,
Ref. "Can Velocity " for formula.
Magnehelic Gauge
An instrument used to measure differential pressure drop.
Manometer
A U-shaped tube filled with a specific liquid. The difference in height between the liquid in each leg of the
tube gives the difference in pressure on each leg of the tube. Used to monitor differential pressure.
Micron (
µ
m)
A unit of length,
1
/
1000
of one millimeter (
1
/
24,000
of an inch).
Negative Pressure System
A system where the fan is located after the dust collector on the clean air side, pulling air through the
system.
OEM
Original Equipment Manufacturer.
Particulate
Any airborne solid material.
Permeability
A measure of fabric porosity of openness, expressed in cubic feet of air per minute per square foot of
fabric at a 0.5" w.c. pressure differential.
Photohelic Gauge
An instrument used to measure the differential pressure drop and to initiate the cleaning system by
means of adjustable "high" and "low" set points for automatic actuation of a sequential timer.
Positive Pressure System
A system with a fan located prior to a dust collector on the dirty side, pushing air through the system.
Precoat
Material added to the air stream at start-up to aid in establishing the initial dust cake on the filter media.
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