Flow control valves

Claim 1

A FLOW CONTROL VALVE COMPRISING A CASING HAVING A BORE THERETHROUGH, SAID BORE HAVING A PAIR OF SPACED ANNULAR RETAINER MEMBERS THEREIN, EACH HAVING AN ANNULAR GROOVE ON ITS INNER SURFACE, A SEAL RING POSITIONED IN EACH OF SAID ANNULAR GROOVES, ONE OF SAID RETAINERS DEFINIG A PARTITION, THE SPACE BETWEEN SAID RETAINERS ON ONE SIDE OF THE PARTITION DEFINING A LOW PRESSURE CHAMBER AND THE PORTION OF SAID BORE ON THE OTHER SIDE OF SAID PARTITION DEFINING A HIGH PRESSURE CHAMBER, EACH OF SAID CHAMBERS HAVING A PORT, A POROUS TUBE IN SAID HIGH PRESSURE CHAMBER, SAID PARTITION HAVING A PASSAGEWAY FOR MOVEMENT OF SAID POROUS TUBE THERETHROUGH, A STEM EXTENDING LONGITUDINALLY IN SAID CASING BORE AND HAVING A CYLINDRICAL PORTION EXTENDING THROUGH SAID ANNULAR SEALS, SAID STEM HAVING AN ENLARGED PORTION WITH EXTERNAL THREADS THEREON, SAID BORE HAVING A PORTION WITH INTERNAL THREADS COACTING WITH THE THREADS ON SAID STEM WHEREBY UPON ROTATION OF SAID STEM THE LATTER WILL BE LONGITUDINALLY MOVED IN SAID CASING BORE, SAID POROUS TUBE BEING SECURED AT ONE END TO THE INNER END OF SAID STEM AND EXTENDING LONGITUDINALLY THEREOF FOR MOVEMENT OF SAID POROUS TUBE THROUGH SAID PASSAGEWAY, SAID POROUS TUBE BEING MOUNTED SO THAT PORTIONS THEREOF MAY BE IN COMMUNICATION WITH BOTH OF SAID CHAMBERS FOR FLOW OF FLUID THEREBETWEEN, AN ABUTMENT IN SAID BORE FOR THE ENLARGED PORTION OF SAID STEM TO LIMIT THE INWARD MOVEMENT OF THE LATTER, SAID POROUS TUBE, WHEN SAID ENLARGED PORTION IS AGAINST SAID ABUTMENT, BEING ISOLATED FROM THE SPACE BETWEEN SAID ANNULAR SEAL RINGS.