Self-optimizing odorant injection system

In a method for odorizing natural gas or liquefied petroleum gas flowing through a pipeline by injecting an odorant from an odorant storage tank through an injection conduit into the pipeline at a desired rate controlled by flow-control apparatus in the injection conduit, the improvement comprising the steps of:

• communicating a pressurized source of inert gas with the odorant storage tank for maintaining the tank at a desired positive pressure above ambient but below the pressure of the pipeline;
• locating a hydraulic pressure booster in the injection conduit for pressurizing the odorant in the injection conduit to a pressure above that of the pipeline, the hydraulic pressure booster communicating with the odorant being injected and having a hydraulic-pressure side which is isolated from the odorant being injected;
• repeatedly supplying hydraulic fluid to the hydraulic-pressure side to thereby cause odorant to flow through the injection conduit and the flow-control apparatus into the pipeline, the flow-control apparatus including a motor-controlled flow valve which allows larger volumes of chemical to be injected into the pipeline and a drop-wise flow valve for metering smaller volumes of chemical being injected, the supply of hydraulic fluid being affected by the action of an electronic linear actuator in response to commands from an electronic controller.