Title: Method and device for controlling fluid pressure

Abstract: The fluid forced by a pump 1 through a conduit 2 towards a point of use such as a spraying bar 6, passes through a gate valve 7 which generates a pressure drop. The higher pressure P0 and the lower pressure P1 thus determined act on a diaphragm 10 which carries a flap valve member cooperating with a seat 18 formed at the inner end of a discharge tube 15-5 which returns the liquid to the tank from which it is pumped. An auxiliary diaphragm 17 acts in the reverse direction. As soon as the pressure difference P0 - P1 exceeds a given value, the flap valve member 14 closes. It is easily demonstrated that under such conditions the delivery pressure P1 is proportional to the pressure drop P1-P0, irrespective of the flow rate through the nozzles of the sprayer bar 6. If 1 is driven at a constant speed, P1 therefore remains constant. The invention is particularly applicable to agricultural sprayers.

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Inventors: Volat, Jean-Pierre (Merseille, FR)
Berthoud, Fernand (Belleville-sur-Saone, FR)
Berthoud, Guy (Belleville-sur-Saone, FR)

Application Number: 496732
Filing Date: 1974-08-12
Publication_date: 1976-01-20
Assignee: Berthoud, S.A. (Belleville-sur-Soane, FR)
Primary Class(es): 222/627 137/115.16, 222/318, 417/299
Other Classes:
US Patent Ref:

2459000	Jan, 1949	Morris	417/300.
2594689	Apr, 1952	Sharp et al.	137/117.
3450223	Jun, 1969	Jones	222/178.
3773222	Nov, 1973	Fiebiger	222/57.

Other Refs: 832,854

Oct, 1938	FR

Primary Examiner: Knowles, Allen N.
Assistant Examiner: Lane, Hadd
Attorney: Dowell & Dowell