Glossary of Terms

These terms cover industrial ventilation principles and the features and components of air filtration equipment:

ABORT DAMPER / CARZ DAMPER: A damper used to divert flames outside and away from collection equipment to avoid an explosion / fire.

ACTIVATED CARBON: A form of carbon with small pores that increase the surface area available for adsorption of chemicals and odors.

AIR-TO-CLOTH / AIR-TO-MEDIA RATIO:  This ratio is the volumetric flow rate of air flowing through a dust collector's inlet duct divided by the total cloth area in the filters. The result is expressed in units of velocity.

AIR EXCHANGE RATE: The air exchange rate or air changes per hour is a measure of how many times the air within a factory is filtered and replaced.

AIRLOCK: Rotary vane which prevents air from entering a dust collector while allowing dust to drop out from the collector. A rotary airlock uses a roatating wheel on the dust collector hopper to continuously dump dust while mainting an air seal.

AMBIENT AIR CLEANING: Collecting and filtering the air from an entire room or facility, rathen than capturing pollutants at their source. Also known as General Ventilation.

ASHRAE:  ASHRAE was formed as the American Society of Heating, Refrigerating and Air-Conditioning Engineers. They establish standards for the rating of air filters 

BACKDRAFT HOOD:  A ventilated slotted hood behind a work area that draws particulate backwards and away from the operator

BAGHOUSE: An air filtration device which collects particulate from industrial processes using filter bags instead of cartridges. 

BACKWARD INCLINED (BI) FAN: A fan with backward inclined blades, moves air with high efficienty matching the velocity of air passing through the fan wheel. typically used in high-volume, low-pressure applications.

BLAST GATE: A sliding damper designed to close off ductwork or source capture devices when they are not being used.

BLOWER: An assembly including an AC electric motor attached to a blower wheel.

BREATHING ZONE:  The area around a worker’s mouth and nose. 

CAN VELOCITY: The speed of dust-laden air as it passes in between dust collector filters.

CAPTURE ARM: A self-supporting articulated arm designed to extract dust, fumes and other airborne pollutants.

CAPTURE AT SOURCE / SOURCE CAPTURE: Air filtration equipment designed to remove contaminants at their source rather than cleaning ambient air. Also known as local exhaust ventilation. 

CAPTURE VELOCITY: The air velocity (FPM) around the hood or table opening necessary to overcome opposing air currents to successfully capture contaminated air. 

CARRYING VELOCITY: Air velocity required to prevent particulate from settling in ductwork. To keep contaminants airborne, velocities of 2000 to 5000 ft/min are typical depending on particle size. 

CARTRIDGE FILTER:  A cylindrical air filter with pleated media designed to fit into various air filtration units. 

CFM: Short for cubic feet per minute, a measurement of the velocity at which air flows into or out of a space. 

CARBON IMPREGNATED POLYESTER SUBSTRATE: Cut-to-size sheets of disposable odor and fume filters, compromised of activated carbon impregnated polyester filter media. 

COLLISION AVOIDANCE: Fume Tracker feature which prevents the hood from contacting the welder.

COMBUSTIBLE / EXPLOSIVE DUST: Metallic or non-Metallic airborne dust with a high enough KST value (see below) to cause a fire or explosion.

CSA (Canadian Standard's Association): The CSA provides testing and certification, product evaluation, energy efficiency verification and standards for motors and electrical equipment. 

CYCLONE COLLECTOR: A dust collector using the centrifugal force or a vortex to seperate particulate from an airstream without the use of air filters

DOWNDRAFT TABLE:  A Self-contained filtration unit designed to draw pollutants down into the table, filter them and return clean air into the facility. 

DIAPHRAGM VALVE: Compressed air valve on reverse pulse collectors, controlled by a solenoid valve that opens to allow compressed air from the air tank to pulse cartridge filters.

DUST COLLECTOR:  A self-contained air filtration unit designed to be ducted to multiple extraction points to capture and filter dust and fumes, exhausting clean air back into the facility. 

DUST DRAWER/TRAY/HOPPER AND DRUM: The part of a dust collector or fume extractor where dust settles after filter cleaning for easy disposal. 

ELECTROSTATIC PRECIPITATOR: A collector that captures dust particles from an airstream, using a high-voltage electrostatic charge to generate an ionization field, capturing the particles on charged plates.

ENVIRONMENTAL BOOTH: An enclosed booth ventilated with air filtration equipment to draw dust and smoke away from the operator. 

ETL MARK: The ETL Listed Mark indicates to distributors and customers that a product has been tested by Intertek and found in compliance with accepted national standards.

EXPLOSION VENT / RUPTURE PANEL: A relief port designed vent pressure in the event of an explosion and protect employees and property by directing the blast.

EXTERNALLY ARTICULATED ARM:  A fume extraction arm with joints and hardware located outside of the arm, as opposed to an internally articulated arm for easy maintenance. 

FACE VELOCITY: The velocity of air measured at the face of an exhaust capture hood. 

FAN CURVE: A graph detailing a fan's performance, showing the relationship between the fan's airflow and the static pressure generated at various CFMs. The curves also show horsepower for each quantity of CFM. 

FIRE RETARDANT FILTER MEDIA: A coating treatment that prevents filter media from burning unless combustible dust present on the filter catches fire.

FPM: The air velocity in feet per minute at which air passes through an opening or filter.

FUME EXTRACTOR:  A machine that uses suction to remove from the environment smoke and fumes generated by welding, soldering and other processes. 

FUME TRACKER: A self-positioning fume arm with servo motors, sensors on the hood see the light from the arc and move the arm into position.

FUMES: Small solid particles formed by the condensation of vapors in solid materials.

HEPA FILTER:  A High-efficiency particulate air filter (HEPA) removes 99.97% of at 0.3 micron and is well suited in applications involving the capture of toxic stainless steel welding fumes. 

HEXAVALEANT CHROMIUM: A byproduct of welding on stainless steel, hex chrome fumes are carcinogenic and require the use of a HEPA filter. 

HOOD: A shaped inlet designed to capture contaminated air and direct it into a filtration unit.

HOPPER: A large, pyramidal shaped container used in industrial processes to hold particulate matter that has been collected from expelled air 

KST VALUE:  KST is the dust deflagration index, and it measures the how explosive a dust is compared to other dusts. Any material with a KST value greater than zero is considered to be at risk of an explosion.

INJECTION CLEANING SYSTEM: A patented filter cleaning technology involving a pneumatic rotating air jet which moves up and down a filter cartridge removing dust. 

INLINE CENTRIFUGAL (ILC) FAN: The motor, fan and inlet cone are packaged into a tubular centrifugal housing for improved performance, quieter operation and simplified maintenance. 

LEXAN: A transparent plastic (polycarbonate) material of high impact strength, used for see-through side and back wall on downdraft tables 

LOUVER: A device containing horizontal angled slats, when mounted on an inlet, it alows dirty air in but prevents dust from being ejected from the collector during pulse cleaning..

MAGNETIC NOZZEL BASE: A magnetic base which can be mounted and secured to metal surfaces to properly position the suction nozzle  

MANOMETER:  An instrument for measuring air pressure; the amount of displacement of a liquid indicates the pressure being exerted on the instrument. 

MERV: (Minimum efficiency reporting value), known as MERV rating is a measurement scale designed by ASHRAE  to rate the efficiency of air filters

METAL MESH PREFILTER: A spark arrestor made of aluminum mesh designed to extinguish sparks before they reach the main cartridge filter.

MICRON (µ): A unit of length, the thousandth part of 1 mm or the millionth of a meter.

MINIHELIC / MAGNAHELIC GUAGE: These Gauges are used to measure positive, negative and differential pressures. They measure pressure drop across air filters to establish when it is time for them to be changed 

MIST: Small droplets which are ordinarily liquid at normal temperature and pressure.

MSDS (Material Safety Data Sheet): Data sheet on materials and chemicals from the manufacturer. Includes health and safety details, flash point, health effects, reactivity, disposal and protective equipment guidelines. 

NANO-FIBER: Filter media with microscopic fibers designed capture fine particulate and are surface loading filters, allowing for easy filter cleaning

NFPA: (National Fire Protection Association) is a  trade association which establishes regulations of the proper handling of combustible dust (NFPA 484)

OSHA: The United States Occupational Safety and Health Administration (OSHA) is an agency which regulates indoor air quality and proper ventilation to maintain a safe environment for workers.

PAINT BOOTH: A paint booth is a structure designed to exhaust overspray and clean the air around parts being painted. 

PRE-COATING: Immersing the filter media in a solution to provide the fibers with a coating that will increase filter efficiency on start-up 

RE-ENTRAINMENT: The re-depositing of dust on the filter surface after it has been pulsed off. Re-entrainment is usually caused by turbulence in the hopper or dirty air plenum. 

REPLACEMENT AIR: Air required to replace exhausted air, can require costly air makeup units in heated or air conditioned facilities.

PRESSURE DROP: Resistance to air flow; may refer to pressure differential across the filter media or the pressure drop across the entire system.

REVERSE PULSE FILTER CLEANING: A quick release of pressurized air through a blow tube into a cartridge filter. This filter cleaning process is more effective with offline pulsing rather than online pulsing which prevents re-entrainment. 

PLENUM: A chamber designed to equalize pressure to equally distribute air across the enclosure.

PULSE CYCLE: The interval of time between pulsing cartridge filters typically 30-45 seconds.

PUSH-PULL SYSTEM: A system in which ambient air is blown in circular airflow patterns by air cleaners or where air is pushed then pulled from one side of the room to the other using a ducted system.

REGAIN: The recirculation of exhausted air back to the front of a dust control booth, improving performance and containing dirty air within the enclosure.

SIDESTACK SILENCER: A duct muffler designed to reduce the dB level of an air filtration unit.

SOLENOID VALVE: An electromechancial valve found in reverse pulse systems. The valve opens to intiate a jet of compressed air into dust collector filters.

SPARK COOLER / SPARK ARRESTOR / SPARK TRAP: A spark arrestor or spark cooler is any device which prevents the emission of sparks into a flammable environment. 

SPARK DETECTION AND SUPPRESSION SYSTEM: The system detects a spark or burning material in the ductwork upstream of the dust collector and suppress it with  water before it can travel to the collection equipment.

SPUNBOND POLYESTER FILTER:This filter media composed of polyester permits users to wash the cartridge in water, making spunbond filters ideal for wet, sticky and humid applications.

STATIC PRESSURE: Static pressure, usually expressed in inches water column (iwc), is the pressure exerted on a surface at rest with respect to the air moving in duct. 

TEFC MOTOR: Totally enclosed, fan-cooled motors offer protection against dust and moisture. They are equipped with a cooling fan to prevent overheating.

THROW (AMBIENT UNITS): The distance an ambient unit can blow air from its outlet until air velocity reaches 50 FPM.

TWA (TIME WEIGHTED AVERAGE): Worker's average airborne exposure which cannot be exceeded in any 8 hour shift. OSHA establishes TWA per contaminant by setting the max mg/m.

ULPA FILTER: Ultra Low Penetration Air Filters can collect 99.997% of particles at 0.3 micron.

UPBLAST MODULE: A module designed to redirect the airflow upwards into carbon modules or after filters. 

V-BANK:  A v shaped module designed to hold carbon granules.   

VENTURI: Air pulse jet design which increases the efficiency of a compressed air pulse. The shaped throat of the venturi creates an air pulse with more force than conventional reverse pulse jets.

VOCs (Volatile Organic Compounds): Organic chemicals that have a high vapor pressure at room temperature, causing toxic vapor to evaporate, often with a strong odor. 

WET DOWNDRAFT TABLE: A filtration unit designed to safely handle combustible dust by drawing particulate down into the table, filtering the dust using cascading water and returning clean air into the facility. 

WET DUST COLLECTOR: A dust collector designed to safely collect combustible dust by drawing particulate into an inlet, filtering the dust using cascading water streams and returning clean air into the facility.