Air to cloth ratio. Simplified.

Air filtration experts talk about air to cloth ratios a lot. Air to cloth ratio is the amount of air in CFM (cubic feet per minute) per square foot of filter media. Technically, the formula for Air Cloth Ratio is Volumetric air flow rate divided by Total cloth area. It's the single most important measure in dust collection. If your air to cloth ratio is off, a set of filters that normally last 2 years, might only last two months. Some deceptive dust collection salesmen will try to squeeze the numbers or cheat standard air to cloth ratios to beat a competitor's price. The best defense against buying a dust collector that doesn’t cut-it is to educate yourself on air to cloth ratios. Recommended Air to Cloth Ratios A few common air to cloth ratios are listed below: Wood dust 3.5:1 on spunbond, 2:1 on paper media. Ambient Welding Smoke 2.5:1 Robotic Welding smoke 1.5:1 Laser/plasma dust 1:1 Pharmaceutical 2:1 Grinding 2:1 Buffing/Polishing 1.5:1 Take weld smoke for example. Weld smoke is made up of very small particles typically ranging from 0.3 to 1 micron in size. In an ambient setting (factory air), the parts per million or density of smoke in the air will be fairly light. So with the recommended air to cloth of 2.5:1.Say we need 5000 CFM of airflow. We would take 5000 and divide by 2. So we need 2500 Square foot of cartridge media. A common size filter cartridge is 250 square feet. So if we need 2500 square foot of media, that equates to a 10-cartridge dust collector (2500/250). If you were sold a 4-cartridge unit that only has 1000 square foot of media but still draws 5000 CFM, that units filters might last 1-2 months. If you are sold a 10-cartridge unit, the filters will last 1-2 years. If you are sold a 16-cartridge unit, the filters might last 3 years and you might overpay for a system.Take the same smoke, but in a robotic hood application. The smoke is packed into a much more dense airstream with a very high parts per million. The recommended air to cloth ratio is 1.5:1 because the smoke is so much more concentrated. If you were to take the same unit recommended above(10 cartridges), the filters might only last 6 months. The proper dust collector in this robotic application would require 13.3 filters(5000 cfm/1.5 air to cloth/250 SF per filter).Bottom line, if you have questions regarding air to cloth ratios, we would be happy to assist. Call, or send us a message, today.