04527953 is referenced by 27 patents and cites 2 patents.

An improved pump unit for sampling air that operates at a constant air flow rate in the range of 5-5000 cc/min. having a filter for removing particles or vapors from the air stream, an air accumulator, a variable drive pump optionally with a bypass, an electric motor for driving the pump, an optional air reservoir, an orifice which creates a pressure drop in the air stream, an optional bypass for the orifice and a pressure switch connected in parallel to the orifice which monitors a change in the air pressure drop; the improvement in the pump is the use of a digital circuit electrically connected to the pressure switch and a closed loop control means electrically connected to the digital circuit and motor; a digital signal determines the open or closed position of the switch and the control means and allows current to flow or not flow to the motor driving the air pump to provide a constant flow of air through the unit; the pump unit is worn by a worker or is placed in a work area and at the termination of a period of time, such as a work day, the filter is removed and the contents collected are analyzed by conventional techniques such as gas chromatography to determine a level of exposure of the individual or the level of exposure of people working in that area.

Pump unit for sampling air
Application Number
Publication Number
Application Date
October 12, 1984
Publication Date
July 9, 1985
Harry E Betsill
W Barry Baker
Hilmar L Fricke
E I Du Pont de Nemours and Company
F04B 11/00
F04B 39/16
F04B 49/06
F04B 49/00
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