the valve in the closed state is accomplished by a portion of seal 88 being urged against upstream conical surface 68 on valve body 54 u2014 as indicated by the arrows as p 1 increases with respect to p 2 the force urging seal 88 again upstream conical surface 68 increases seal 88 is an annular ring made of flexible material exemplary materials include natural rubber synthetic rubber and silicon it preferably incorporates mechanical interlocking features to hold it in position in this example a downstream facing protrusion on seal 88 fits into an annular cavity in an upstream facing portion of downstream housing 70 spring retainer 86 compresses a portion of seal 88 against downstream housing 70 to hold it in place spring retainer 86 is clamped in position as threaded engagement 82 is tightened the compressible nature of seal 88 provides a positive retaining force for the assembly similar to the function of a lock washer the reader will note that spring retainer 86 includes features configured to positively locate compression spring 84 spring 84 bears against spring retainer surface 64 on valve body 54 the spring thereby holds valve body 54 in the closed position shown of course as pressure within reservoir 26 builds the closing force of spring 84 will be overcome and the valve will crack open u2014 much like a pressure regulating valve this action is not desired in the present invention one goal of the present invention is.