is received between the wall 76 and a concentric radially inner wall 80 also formed on the lower edge of the sleeve 22 by supporting the seat 52 in this manner it can be appreciated that surface area dedicated to supporting the seat within the center of the regulator flowpath or fluid passage has been kept to a minimum as best seen in fig4 there is an open flowpath of about 340 u00b0 around the seat significantly reducing the potential for obstruction and also minimizing pressure loss through the regulator seat 52 is preferably formed of a rigid plastic material for example a glass fiber reinforced polyphenylene sulfide pps resin preferably the material has a minimum flexural modulus of 1 8 msi astm d790 for one size regulator the seat 52 may have an outside diameter of 0 494 inch and the support ring 58 may have an inner diameter of 0 669 inch the outer diameter of the support ring 58 may be 1 135 inch and the height may be 0 400 inch of course the dimensions may change for different size regulators returning to fig1 adjacent the annular walls 76 and 80 there are seated a pair of inner and outer o rings 82 84 respectively which insure that fluid flowing through the regulator in the direction from inlet 18 to outlet 20 as indicated by the flow arrow f is constrained to flow through the reciprocable plunger 28 and around the seat 52 as described below note that the cap 24 is held securely in place within a counterbore formed in the housing outlet section 14 so that upon assembly of the upper housing section 14 to the lower housing.