8 threadedly secured to the nozzle holder 7 numeral 6 designates a valve rod having its front part fitted into the valve body 8 and its rear part fitted into a lever holder 9 thereby supporting it in place numeral 10 designates a rear cap formed with a fluid feed port 15 opening to its rear end face and the lever holder 9 is threaded into its front part thereby fixing it in place numeral 11 designates an operating lever inserted into an opening 29 formed in the lever holder 9 and pivotably attached to the lever holder 9 with a pin 12 numeral 30 designates a forked portion formed at the rear end of the operating lever 11 to hold the valve rod 6 and adapted to be pressed against the front face of a large diameter portion 26 formed at a predetermined position of the central portion of the valve rod 6 also the valve rod 6 is forwardly urged by a spring 13 mounted between the rear face of the large diameter portion 26 and the lever holder 9 the forward end of a conical head 24 at the forward end of the value rod 6 is inserted into a flow passage 19 formed in the valve seat 5 so as to be urged into closed position by the force of the spring 13 the suction nozzle 4 is detachably fitted on a small diameter portion 23 of the nozzle holder 7 and held by seal members o rings 27 and 28 mounted.