| 摘要 |
A pressure control valve (10) reduces the pressure of a fluid, flowing into its inlet duct (11), to a pre-set and substantially constant value before delivering it from its outlet duct (13). Said valve (10) has a plug member (12) which is made to slide axially, against the adjustable action of a spring (28), by the pressure in the outlet duct (13), to close an aperture connecting the outlet duct (13) to the inlet duct (11) when said pressure reaches the pre-set value. The plug member has an O-ring (21) to seal off a further passage between the outlet duct (13) and inlet duct (11) during normal operation. The groove (22) housing the O-ring has a step (23) on the side facing towards the portion in communication with the inlet duct (11) so as to prevent the seal of the O-ring when the pressure in the outlet duct becomes higher than the pressure in the inlet duct. In this way, whenever a pressure drop occurs in the inlet duct (11), the pressure in the system connected to the outlet duct (13) is automatically relieved. <IMAGE> |
