The 25P is a self-actuated pilotoperated pressure regulator. Downstream pressure is fed back through an external sensing line to the pressure pilot,which adjusts the opening of the main valve so as to maintain the set pressure. The main valve can close tight for ANSI/FCI 70-2 Class IV shut off when steam is not required.
Spirax Sarco Pressure Reducing Main Valve, Pilot Operated, 1 in Nominal, NPT, 250 psi, 450 deg F, Cast Iron Body, Media: Steam, 18.9 in H