Housing with a gas-extraction device

摘要

In a row of fume-extraction cabinets, each cabinet is closed by a door and is connected by an associated line to a common collecting line which, in turn, leads to an air-extraction fan. Within each line there is seated a rotatable throttle which is connected via a linkage to its associated door, so that when the door is closed, the line is progressively throttled to reduce the flow rate of air which is extracted from this fume-extraction cabinet. A potentiometer is connected such that it rotates together with the respective throttle and the signals generated are fed to a summing amplifier which varies the rotational speed of the extraction fan as a function of the number of open doors, in order to match the demand and performance of the air extraction system.