Injector-recirculation pump

Claim 1

An injector-recirculation pump adapted to be flow connected to a source of power fluid and further adapted to be flow connected to a source of treatment chemical and to a wellhead so that chemical can be injected into the wellhead and at the same time a portion of the chemical can be recirculated back to the source of chemical; said pump comprising: a housing forming a chamber, a bellows, an over the center actuator, a power fluid valve means adapted to be moved from one to another flow control position, a pump means having a cylinder and a piston with said piston being reciprocatingly received within said cylinder; flow conduit means connected to provide flow path to and from said pump means; check valve means within said flow conduit and located upstream and downstream of said pump means; said bellows being housed within said chamber; a flow conduit means connected to provide a flow path to and from the interior of said bellows, a check valve means located upstream and downstream of said bellows and within the last said conduit means for permitting flow to occur in one direction through said bellows; means connecting said over the center actuator to said power fluid valve means for connecting the power fluid to the housing when the power fluid valve means is in said one position and for connecting the housing to the atmosphere when the power fluid valve means is in said another flow control position; means connecting said piston to said bellows and to said over the center actuator means so that said bellows, when contracted, reciprocates said piston to thereby force fluid within said cylinder to flow along a first flow path while fluid contained within said bellows is forced to flow along another flow path; and means including a valve downstream of said bellows for controlling the rate of response of said piston.