Relievable check valve for medical lines

Abstract

This invention concerns relievable normally closed check valves for use in conjunction with fluid delivery systems for medical patients, as well as methods for making and using valves. In the medical context, such valves function at very low fluid pressures, and include a multi-part valve body made from upper and lower housings capable of movement relative to each other that, when operably connected, dispose between them a compliant or deformable, resilient valve element normally biased in the closed position against a valve seat present on the inner surface of the upper housing. The upper housing also includes a lower housing seat. The inside surface of the lower housing contains or supports a structure that positions the valve element to engage the valve seat in the absence of fluid pressure above the valve's pre-determined cracking pressure. The valve's flow prevention function may be relieved in the absence of sufficiently pressurized fluid by causing the valve element to disengage from the valve seat, for example, by adjusting the valve body to distance the valve element from the valve seat.

1 . A relievable one-way check valve, comprising:
 (a) a valve housing having a valve seat;   (b) a valve element within the valve housing that is biased against the valve seat in a normally closed position but that opens when exposed to a pressure differential that meets or exceeds a rated cracking pressure for the valve; and   (c) a valve relief feature that, when actuated a user, opens the valve to fluid flow at a pressure that is less than a rated cracking pressure for the valve.   
     
     
         2 . A valve according to  claim 1 , wherein the valve relief feature, when actuated, causes change in a physical relationship between the valve seat and valve element, resulting in fluid flow through the valve even if the pressure differential across the valve element is less than the rated cracking pressure for the valve. 
     
     
         3 . A valve according to  claim 1 , wherein the valve relief feature, when actuated, causes application of a pressure other than fluid pressure to create a sufficient pressure differential between the inlet and outlet sides of the valve element to cause the valve to open and permit fluid flow. 
     
     
         4 . A valve according to  claim 1 , wherein the valve relief feature, when actuated, provides a second flow through the valve that avoids the valve element.