Backflow-preventing valve

US4518006A · kind A · utility

Assignee

• Lang Apparatebau GmbH · DE

Inventors

• Peter Hoffmann · Korschenbroich, DE
• Walter Evers · Ennepetal, DE

Key dates

• Filing date: Mar 10, 1983
• Grant date: May 21, 1985
• Expiry date: Mar 10, 2003

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T137/3331
• WIPO field: Civil engineering
• WIPO sector: Other fields

Abstract

A backflow-preventing valve for connection between a high-pressure input line and a lower-pressure output line has a valve housing forming upstream and downstream chambers and having an inlet opening into the upstream chamber remote from the downstream chamber, a vent opening into the upstream chamber offset from the inlet, and an outlet opening into the downstream chamber. A check valve in the downstream chamber allows flow only from the upstream chamber into the downstream chamber. A tubular piston sealingly engaged across the upstream chamber upstream of the vent, formed with a throughgoing bore, and having a downstream end engageable with the check valve is movable between an upstream position with its downstream end in the upstream chamber spaced from the check valve and a downstream position with its downstream end engaged sealingly with the check valve. Fluid flow through the bore from the inlet to the vent is only possible in and between the upstream position and an intermediate position of the piston. A spring urges the piston into the upstream position. A valve body fixed in the housing and sealingly engageable in the piston bore in and between the intermediate and upstre…