Packless valve with anti-frost means

Claim 1

A DIAPHRAGM-TYPE VALVE COMPRISING A VALVE BODY PROVIDED WITH INLET AND OUTLET PORTS IN COMMUNICATION WITH EACH OTHER THROUGH AN INTERPOSED VALVE SEAT, A VALVE ELEMENT IN SAID VALVE BODY INCLUDING SEALING MEANS MOVABLE INTO ENGAGEMENT WITH SAID VALVE SEAT TO INTERRUPT FLUID COMMUNICATION BETWEEN SAID PORTS, A VALVE BONNET JOINED TO SAID VALVE BODY, A VALVE STEAM THREADEDLY MOUNTED IN SAID VALVE BONNET FOR ROTATIONAL AND RECIPROCATING MOVEMENT WITHIN SAID VALVE BODY, SAID VALVE STEM AT ITS INNER END BEING ENGAGED WITH SAID SEALING MEANS TO MOVE THE SAME TOWARD AND AWAY FROM SAID VALVE SEAT, SAID SEALING MEANS INCLUDING DIAPHRAGM MEANS SUB-DIVIDING THE INTERIOR OF SAID VALVE BODY INTO A STEM RECEIVING AREA AND A FLUID FLOW AREA WHEREIN SAID VALVE SEAT IS LOCATED, A FLEXIBLE IMPERVIOUS CUP-LIKE SEAL CAP MEANS HAVING AN ENLARGED OPEN END FLUIDTIGHTLY RECEIVED AROUND A PORTION OF SAID VALVE BONNET, AN OPENING IN SAID CUP-LIKE SEAL CAP MEANS THROUGH WHICH SAID VALVE STEM FLUIDTIGHTLY EXTENDS, SAID DIAPHRAGM MEANS AND SAID CUP-LIKE IMPERVIOUS SEAL CAP MEANS DEFINING WITH SAID BONNET A VOLUME WHICH REMAINS SUBSTANTIALLY CONSTANT REGARDLESS OF THE POSITION OF SAID VALVE STEM.