Flow-sensitive sensing and shut-off device

Claim 1

A flow-sensitive sensing device responsive to flow differences between two fluid lines to detect abnormal flow in one line without fluid intercommunication between the two lines by way of the sensing device and without controlling flow to compensate for such flow differences comprising a housing; entirely separate first and second fluid lines in fluid flow connection to and from the housing; first and second chambers in the housing; first channels in the housing connEcted with the first chamber and constituting a first fluid flow path for the first fluid line through the housing; second channels in the housing connected with the second chamber and constituting a second fluid flow path entirely separate from the first fluid flow path for the second fluid line through the housing; there being no fluid flow connection between the first and second fluid flow paths in the housing; a first flow-responsive member in the first chamber having surfaces exposed to upstream and downstream fluid pressure in the first fluid flow path, reciprocably movable between first and second positions, and disposed across the line of flow in the first fluid flow path; and a second flowresponsive member in the second chamber having surfaces exposed to upstream and downstream fluid pressure in the second fluid flow path and disposed across the line of flow in the second fluid flow path, linked to the first flow-responsive member and reciprocably movable therewith between first and second positions; each flow-responsive member having a laminar flowrestricting passage disposed thereacross carrying all normal fluid flow in the fluid flow path across which the flowresponsive member is disposed, each flow-restricting passage producing a normal pressure differential across said flowresponsive member between the upstream and downstream surfaces, to urge it towards one of its two positions, the flow in each fluid line creating opposing differential pressures across the first and second flow-responsive members in the first position under normal flow, and moving the two flow-responsive members to the second position whenever under abnormal flow in one fluid line a predetermined flow differential between the two lines is reached or exceeded, such movement being without compensation for such abnormal flow.