Introduction to Baghouse / Fabric Filters: Glossary
BLEEDTHROUGH: Dust penetration through the bags.
BLINDING: The flow restriction that occurs in filter bags when dust becomes lodged in the media, causing high differential pressure (a normal condition over time).
BLOWPIPE: A pipe or manifold that is used in a pulse jet baghouse to direct air jets into the tops of the bags for cleaning.
CAGE: A wire structure used to support filter bags in a pulse jet baghouse.
CELL PLATE (TUBESHEET): Internal divider surface that separates dirty from clean gas plenums and where the bags are seated.
CLEAN ON DEMAND: The process of cleaning bags based on differential pressure as opposed to a timer.
COMPARTMENT: A segmented filtering section of a baghouse that can be isolated from the others.
DIFFERENTIAL PRESSURE, ∆P: The resistance to flow across (through) a baghouse, measured in “inches of water” column or “inches H2O.”
FILTER MEDIA: The type of cloth used in filter bags.
FLEX FAILURE: Caused by excessive movement, such as under-tensioning or over-cleaning.
HOPPER BAFFLE: A device located in the baghouse hopper to help evenly distribute the air and dust flow into the bags. May also act to knock out big particles.
IMPINGEMENT: The act of particulate striking the bags and becoming attached.
INSIDE COLLECTION: The collection of dust on the interior side of the bag, as in a reverse air collector.
INTERSTICES: The open voids in the filter bag's cloth where air passes through.
LIFECYCLE: The length of time a bag is in service.
MAGNEHELIC GAUGE: Used to measure differential pressure (in inches of water).
MANOMETER: A water-filled, U-style gauge used to measure differential pressure.
MULLEN BURST TEST: An ASTM rupture test for measuring the strength of filter bag material, using PSI/square inches of material.
NULL PERIOD (SETTLE TIME): A time segment during off-line cleaning when the bags are allowed to relax without any cleaning energy supplied. This allows the displaced dust to fall off the bags and settle below the inlet opening.
OUTSIDE COLLECTION: The collection of dust on the exterior surface of the filter bag, as in a pulse jet collector.
PERMEABILITY: The measurement of air flow in CFM through one square foot of filter bag at 0.5″ H2O ∆P (ASTM standard).
P/J: Pulse jet baghouse.
PLENUM: The baghouse housing area above or below the tubesheet, either dirty or clean.
POPPET VALVE: An efficient sealing valve used on the outlet side of a baghouse to isolate the gas flow.
PRE-COAT: A protective coating added to the filtering surface of bags to aid in start-up and/or collection efficiency.
PREMATURE BLINDING: A flow restriction to filter bags that requires earlier replacement than expected. Typically the result of improper new bag startup or over-cleaning.
PRESSURE DROP, ∆P: see DIFFERENTIAL PRESSURE.
PULSE DURATION: The time a diaphragm valve is open during the cleaning of a pulse jet baghouse.
R/A: Reverse air baghouse.
SELENOID VALVE: An electromagnetic pilot valve used to activate a diaphragm valve on a pulse jet baghouse.
SURFACE FAILURE: Caused by high particulate velocity, sand blasting, or friction rubbing from other source.
TUBESHEET (T/S): see CELL PLATE
VENTURI: A cone-shaped device located in the top of a pulse jet bag to help concentrate the high pressure cleaning air jet.
WEIGHT: Bags are selected based on average weight per square foot.