Patent ID: 8349038

Claim:
In a system for injecting a chemical from a chemical supply into a natural gas or liquefied petroleum gas pipeline at a desired injection rate, the system including a chemical storage tank, an injection conduit extending from the storage tank to the pipeline, and flow control apparatus in the injection conduit, the improvement comprising: a hydraulic pressure booster located in the injection conduit upstream for pressurizing the chemical to a pressure above that of the pipeline, the hydraulic booster having a first side communicating with the chemical being injected and an isolated side which is exposed to hydraulic pressure but which is isolated from the chemical being injected; the flow control apparatus being fed by the hydraulic pressure booster and including (a) a motor-controlled flow valve which allows larger volumes of chemical to be injected into the pipeline and (b) a drop-wise flow valve for metering smaller volumes of chemical being injected; a linear thruster controlling the hydraulic pressure booster; and an electronic controller controlling the linear thruster.