Airvate Blog

  Three sections in this blog: Push-pull ventilation system and its advantages Disadvantages of general ventilation and side exhaust systems Methods to design a push-pull ventilation system Push-pull ventilation system and its advantages Open surface tanks used in industrial processes often need ventilating to remove harmful pollutants (vapors, fumes or aerosols) from the working environment. One method of removing pollutants is the so-called side push-pull ventilation system, in which a jet of air is blown (or pushed) from one side of the tank and collected (or pulled) by an exhaust hood on the opposite parallel side. This system is particularly useful for large tanks where access requirements preclude the use of an overhead canopy, and the size of the tank makes side (or rim) exhaust systems prohibitively expensive. Most agree that a push-pull ventilation system can yield air savings of up to 50% compared to a side suction only hood. An illustration of a push-pull system for an o...

Introductory Air balancing, trouble-shooting, and system evaluation in dust collection and industrial ventilation systems all require accurate measurements of air flowrates. Normally, the Pitot tube and magnehelic gauge (or manometer) are used to measure the velocity pressure and static pressure inside of a duct (round or rectangular), and then the air flowrates are calculated based on the measured values. This article talks about 5 kinds of uncertainties that always happen in field measurements using Pitot tube, the estimated maximum errors with some of them, and how to avoid some uncertainties with recommendations from manuals and standards ( ISO 3966 and NF X 10-113).   Uncertainties, maximum errors, and how to avoid some of them In addition to the inherent errors from Pitot tube and gauges themselves (calibration, resolution, drift, etc., sometimes with the correction factor of Pitot tube involved), there are other errors we have to...

  In a dust collecting system, the duct, fan, and dust collector are all susceptible to abrasion from dust particles, high-velocity gas flow, and chemical corrosion. The elbows are most vulnerable to abrasions. Air leakage around an access-door or hopper and loose flange isn’t uncommon either. Many times, these holes on ductwork, fans, and dust collectors are not repaired and left alone, so they grow bigger and bigger and air leakage becomes an even worse problem. Airvate did some calculations to estimate sucked-in air volume through a hole based on available data regarding the hole’s area and gauge pressure inside of a duct or dust collector. The calculations are listed in the table below. Along with the sucked-in air volume, moisture volume is also listed in the last column for an 8-hour shift assuming that the sucked-in air is saturated with water vapor, like what would happen on a rainy day. 4 hole-sizes are selected: 3 round holes of sizes 7/16”, ½”, and 1” in diamet...