Abstract: A valve assembly includes a valve stem having a resilient proximal seal member disposed around the stem and a distal seal member disposed around the stem. The proximal and distal seal members are axially separated from one another along the valve stem. The assembly further includes a housing defining a valve chamber, in which the valve stem is confined so as to be axially displaceable within the valve chamber. The housing defines a first portion of the valve chamber, in which the proximal seal member resides, a second portion of the valve chamber, in which the distal seal member resides, and a cross-bore chamber, which opens into the valve chamber in a third portion between the first and second portions. The third portion has a minimum cross-sectional diameter greater than the cross-sectional diameter of the first portion.

Abstract: A valve assembly (6) comprises a valve stem (21) with a resilient proximal seal member (25) and a distal seal member (28) disposed around the stem. The proximal and distal seal members are axially separated from one another along the valve stem. A housing defines a valve chamber in which the valve stem is confined so as to be axially displaceable within the valve chamber. The housing defines a first portion (41) of the valve chamber in which the proximal seal member resides and a second portion (42) of the valve chamber in which the distal seal member resides. The housing further defines a cross-bore chamber(12) which opens into the valve chamber in a third portion (43) between the first and second portions. The third portion has a minimum cross-sectional diameter greater than the cross-sectional diameter of the first portion, and preferably larger than the uncompressed diameter of the proximal seal member.