Fluid-driven shutoff valve

A fluid-driven shutoff valve including:

• a main body formed with an inlet passage and an outlet passage;
• a valve seat formed in the main body;
• a valve element movable into or out of contact with the valve seat;
• a drive part integrally connected to the valve element;
• and
• a pilot opening/closing valve configured to supply compressed fluid to drive the drive part,
• wherein the pilot opening/closing valve includes:
• (a) a first needle valve, a first motor configured to change an opening degree of the first needle valve, and a first check valve configured to allow the compressed fluid to flow only from the pilot opening/closing valve side to the drive part side, and
• (b) a second needle valve, a second motor configured to change an opening degree of the second needle valve, and a second check valve configured to allow the compressed fluid to flow only from the drive part side to the pilot opening/closing valve side,
• wherein each of the first and second needle valves includes a needle valve element and a needle valve seat, and
• the shutoff valve further includes a vertically-moveable member placed between the first motor and the first needle valve, and a vertically-moveable member placed between the second motor and the second needle valve, each of the vertically-movable members being to be moved by driving of the corresponding first and second motors to relatively move the respective needle valve elements with respect to the needle valve seats.