section 81 and an upper smaller diameter section 82 is arranged in a lower valve housing 83 in which a fluid pressure chamber 84 is formed a conduit 85 equivalent to conduit 33 of fig1 is connected to conduit 56 the interior of housing 83 contains seals such as o ring seals 86 which seal off the space between the inner wall of housing 83 and the surface of the lower valve stem section 81 additional seals 87 seal off the inner wall of housing 83 and the upper stem section 82 a passageway 60 fluidly communicates the line pressure downstream of valve member 67 and valve chamber 84 above seals 86 valve stem section 82 is not connected to valve member 67 the operation of the valve system of fig2 and 3 is the same as the operation of the valve system described with respect to fig1 however the larger surface of the valve stem section 81 provides a greater counterbalancing force than the substantially same surfaces for the lower and upper valve stems as described in fig1 would the diameter d l2 of the lower valve stem section 81 is larger than the diameter d u of upper valve stem 50 thus pressure p r or p a acting on the larger cross sectional area d l2 of lower valve stem section 81 exerts a greater upward force on valve member 67 than the downward force exerted on valve member 67 resulting from the pressure p r or p a acting on the smaller.