open end thereof which bulkhead has a nozzle receiving aperture 20 formed therein in the illustrated exemplary embodiment a closure door 22 is shown with a radially outwardly extending peripheral flange 24 formed thereon which has a plurality of apertures 28 therethrough which may be spaced circumferentially thereabout a flexible annular seal 26 is disposed about the flange and secured thereto as for example by insert molding the seal 26 thereon with portions of the molded seal material passing through the apertures 28 the door 22 may include a one way pressure relief valve not shown which opens to permit flow through central orifice 32 and peripheral slots 34 the nozzle receiving orifice 20 has formed thereabout an annular seating surface 36 which may have a spherical configuration if desired peripheral flange 24 has formed thereon two oppositely disposed downwardly extending brackets 38 40 each of which has spaced apertures denoted respectively 42 44 and 46 48 which are aligned in pairs so as to have received therethrough pins or axles 50 52 which extend outwardly of the brackets 38 40 referring to fig1 through 7 a support structure or housing 54 is disposed on the downstream or undersurface of bulkhead 18 and housing 54 may have a generally u shaped configuration with the legs or sidewalls denoted 56 58 thereof disposed in spaced generally parallel arrangement and may be formed integrally as a one piece member in the.