bellows meets with the fixed housing the configuration of a fixed component in one side of the fluid coupling mating to a movable component on the other side of the fluid coupling provides reliable opening of the valves and sealing around the valves even with relatively loose tolerances this configuration avoids the problem of uncontrolled positioning that can occur in a configuration having fixed to fixed and movable to movable components mating in the case of uncontrolled positioning the mated movable to movable components can u201c float u201d as a pair if the mating fixed to fixed components are not in full engagement e g due to tolerance issues in the configuration described in u s application ser no 10 861 285 for example in some cases the mated poppet valves may u201c float u201d axially resulting in one valve remaining closed due to factors such as differential pressure or unmatched spring forces the fluid coupling is also designed to be easily assembled in addition to stem 22 stem member 16 includes a rear portion 18 and a central portion 20 rear portion 18 includes a barbed end 24 to allow it to be connected to a conduit not shown defining the flow path of the device for example a flexible tubing can be press fit onto the barb 24 the central portion allows the stem member to be attached to shoulder 26 and possibly side wall 27 of first housing portion 12 the central portion 20 also captures the base 56 of bellows seal 30 sealing the base 56 against surface 54 of the first portion 12 fig2 the resulting sub assembly of first housing portion 12.