Techrite Controls Australia...
The B34S is a spring-loaded, self-operated regulator available with or
without internal relief. It combines the B31 8 diaphragm case with the
B34 valve assembly for an economical solution to mid-range commercial
and industrial applications. Among its attributes are an adjustable
loading ring for controlled boost at high flows, precision breather
opening to ensure proper stability under all conditions, and in the R
model, a high capacity internal relief valve. All critical parts are
either steel or aluminum, not plastic, to ensure reliability.