Abstract: Gate valve having a primary seal, actuated by fluid pressure in the flow conduit, for preventing leakage along the gate member on the upstream side of the gate valve and a secondary seal actuated by fluid pressure upon leaking of the primary seal and including a self-actuating relief means to prevent build-up of fluid pressure in the valve body in excess of the pressure in the flow conduit.

Abstract: A system for injecting chemicals into a geothermal well near the bottom of the well bore for optimum efficiency. The system includes a spool assembly with a master valve for control of the geothermal flow and a secondary outlet formed of an angle to permit the chemical injection chamber to be lowered into the well. The secondary outlet is attached to the main spool in such a way as to allow internal thermal expansion while permitting the chemical injection chamber to be fed by capillary tube to the bottom of the well bore. The chemical injection device includes an injection chamber through which the chemical is disbursed and a segmented sinker bar to provide the necessary weight to carry the chamber to the bottom of the well against the geothermal well flow. An annular seal assembly in the spool prevents leaking by being pressure energized by the geothermal production fluid. As a result, production can continue during the chemical injection process.