Patent ID: 8636477

Claim:
A chemical supply system for supplying chemical solution provided from a chemical tank, comprising: a chemical supply pump having a pump chamber and a working chamber, the pump chamber being configured to be loaded with chemical solution from the chemical tank, the working chamber being configured to be loaded with working gas, the pump chamber and the working chamber commonly having a volume-changing member configured to actuate the pump chamber to suction and discharge the chemical solution, the volume-changing member being actuated in response to a pressure of the working gas loaded in the working chamber; a pressure adjuster configured to suction the chemical solution into the pump chamber by setting the pressure of working gas to a suction pressure; a switching controller having a discharge-side opening-closing valve provided in a discharge passage connected to the pump chamber, a suction-side opening-closing valve provided in a suction passage connected to the pump chamber, wherein the switching controller is configured to switch the suction-side opening-closing valve to the open state for starting to fill the pump chamber with the chemical solution when the suction-side opening-closing valve and the discharge-side opening-closing valve are in closed state; a pressure detector configured to detect at least one of a gas pressure in a space connected to the working chamber and a gas pressure in the working chamber when the suction-side opening-closing valve is switched to the open state and starts an inflow of the chemical solution to the pump chamber; a suction controller configured to control the suction pressure applied to the working chamber by the pressure adjuster, based on a detection result of the pressure detector; and a position detector configured to detect a position of the volume-changing member, wherein the switching controller is further configured to control the suction-side opening-closing valve to switch from the open state to the closed state in response to a detection result of the position detector corresponding to a complete position of the volume-changing member, the complete position being for the volume-changing member to complete the suction, and wherein the suction controller is further configured to control the suction pressure applied to the working chamber by the pressure adjuster, for obtaining a constant time required for the position of the volume-changing member to move to the complete position in each suction operation.