Glossary

Average Airflow: During the course of the year, the volume of air passing through the filter will change with temperature, heat load, and other factors. The overall average for the year is the average airflow.

Concentration: Amount of dust in the air. Usually expressed in terms of micrograms/cubic meter of air.

Dust: Small solid particles created by the breaking up of larger particles by processes such as crushing, grinding, drilling, explosions, combustion, etc.

Dust Holding Capacity: Amount of dust that the filter can capture before the pressure drop of the filter exceeds design limits

Dust Loading: The quantity of dust in the gas stream, usually expressed as micrograms of dust per cubic meter of air.

Filter Life time: The time between when the filter is installed and it reaches its design limit on pressure drop

Filter Media: The permeable barrier employed in the filtration process to separate the particles from the fluid stream.

Filtration: A process by which particles are separated from a fluid stream by use of a permeable barrier.

Filtration Efficiency: A measure of the ability of filter media to separate out particles in the airstream. There are many different standards and methods to measure efficiency, making it almost impossible to compare the efficiency of two filters using different standards. Gore Cooling Filters are tested according to DIN 1822 that measures efficiency based on discrete particle count, not mass.

Humidity, Absolute: The weight of water vapor per unit volume, pounds per cubic foot or grams per cubic centimeter.

Humidity, Relative: The ratio of the actual partial pressure of the water vapor in a space to the saturation pressure of pure water at the same temperature.

Hydrophobic Membrane: A thin porous film that has a high surface energy causing water to bead and not pass through.

Micron (µm): A unit of length, the thousandth part of I mm or the millionth of a meter (approximately 1/25,000 of an inch).

Peak Airflow: The maximum volume of air passing through the filter at any given time during the year.

Permeability: A measure of fabric porosity or openness, usually expressed in cfm/ft2 at a 0.5" H20 pressure differential.

PM10: total mass of all particles < 10 µm in diameter.

Pressure Drop: Resistance to air flow; may refer to pressure differential across the cloth, across the baghouse or the pressure drop across the entire system.

System Pressure Loss: Loss in pressure caused by air flowing through louvers, electronic racks or plenums (Pascal or inches of H2O).