The XSTOU 25P pilot-operated steam pressure reducing valve is a pilot valve diaphragm type, available with flange and threaded connections. Contact our online customer service to request a sample. The Spirax Sarco 25 series pilot-operated diaphragm regulating valve controls steam pressure through diverse combinations of the same main valve with different pilot valves. The XSTOU 25P pilot-operated steam pressure reducing valve incorporates significant improvements over conventional pressure reducing valves. It uses a new diaphragm material and greatly increased working area, enabling subtle changes in upstream pressure or downstream load to be accurately and promptly fed back to the main valve diaphragm. This adjusts the main valve opening to ensure stable downstream pressure.

Structural Features:

■ Pilot valve spring: Springs in three colors provide precise pressure control across a range of 0.2–14 bar g.

■ Temperature adjustment dial: Enables quick and accurate setting of the desired temperature.

■ Temperature sensor: Contains uncompensated fluid within the temperature control element that senses instantaneous temperature changes for accurate control.

■ Every 25 series regulating valve is tested before leaving the factory to ensure trouble-free operation.

Working Principle:

Before startup, when the pilot valve spring is in its free state, both the main valve and pilot valve remain closed. The pilot valve opens under spring force, allowing steam to enter the main diaphragm chamber. Some steam escapes through the control orifice. When inflow from the pilot valve exceeds outflow through the control orifice, control pressure in the main diaphragm chamber increases, opening the main valve. As steam flows through the main valve, the increase in downstream pressure is fed back via the sensing tube to act below the pilot valve diaphragm, balancing the spring force above the diaphragm. This gradually closes and throttles the pilot valve, maintaining pressure in the main diaphragm chamber and controlling the main valve opening to deliver the appropriate amount of steam. Adjusting the spring on the pilot valve diaphragm allows changes to the downstream pressure.