Spirax-Sarco 25P Pressure Reducing Valve

Cougar USA is the Spirax Sarco rep in the Houston area. Spirax Sarco provides a broad range of fluid-control products, engineered packages, steam systems expertise and site services for its diverse range of over 100,000 industrial and institutional customers. They help their customers optimize production capacity, reduce energy costs and emissions, improve product quality and enhance the safety of their operations. Spirax Sarco has strategically located manufacturing plants around the world including one near Houston in Pasadena, Texas.

What is a Spirax Sarco 25p?

The Spirax Sarco 25-Series regulators are a versatile family of self-acting pressure regulators with control pilots and interchangeable main valves for most steam applications. Options include pressure reduction (25P), combined pressure reduction with electrical on/off override (25PE), pressure reduction with air loaded pilot (25PA), and as a back pressure regulator (25BP). Designed with the user in mind, the 25-Series offers versatility and simplicity. Color coded, interchangeable springs allow quick and easy change of downstream pressure range eliminating the need to isolate the valve or break the steam line.

Spirax Sarco Pressure Reducing Valve, Pilot Operated, 3/4 in Nominal, NPT, 250 psi, 450 deg F, Cast Iron Body, Media: Steam

Components of the Spirax Sarco 25p

Body Material	Cast Iron
End Style	NPT
Manufacturer	Spirax-Sarco Inc
Manufacturer #	55223
Media	STEAM
Nominal Size	3/4 in
Pressure Rating	250 psi
Temperature Rating	450 degF
Type	Pilot Operated

Operation of the Spirax-Sarco 25P Pressure Reducing Valve

The Spirax-Sarco 25P series pilot-operated reducing valve is widely used in steam systems. Accurate and stable pressure control can be realized irrespective of a change in upstream steam pressure or fluctuation of downstream load.

The Spirax-Sarco 25P series pilot-operated reducing valve is unique in that one, or several, pilot valves can be installed or exchanged on the same valve. Besides being stable and reducing pressure, it can also control the temperature, the upstream pressure or the remote switch.

Operation

Normal positions before start-up are with the main valve closed and the pilot valve held open by spring force or air pressure.

Entering steam passes through the pilot valve into the main diaphragm chamber and also out through the control orifice. As flow through the pilot valve exceeds flow through the orifice, control pressure increases in the diaphragm chamber and opens the main valve. As steam flows through the main valve, the increase in downstream pressure feeds back through the pressure sensing line to the underside of the pressure diaphragm.

When the force below that diaphragm balances the compression force of the spring above it, the pilot valve throttles. The control pressure maintained in the main diaphragm chamber positions the main valve to deliver just enough steam for the desired delivery pressure. Adjustment of the spring or air pressure above the pressure diaphragm changes the downstream pressure set point.

When steam is no longer required, the sensing line pressure increases closing the pressure pilot and the control pressure bleeds back through the control orifice. This allows the main valve to hold the desired reduced pressure, and it may close tight for a dead-end shutoff.

Advantages of Spirax Sarco 25p

Combination of pilots allow for different types of control in one regulator
Patented self scrubbing guide for long, trouble-free service
Fatigue-tested diaphragm designed without a piston to prevent danger of sticking
Stainless steel internals for excellent durability and resistance to corrosion

Typical Installation of Spirax Sarco 25p

The regulator should be installed in a horizontal line with suitable bypass and isolating valves. A steam trap should be installed upstream to prevent condensate from reaching the regulator. The trap and regulator should both be protected with a strainer. The pressure sensing line should be located in a straight section of the downstream piping at least 10 pipe diameters from the nearest fitting. Complete installation instructions are given in IMI3.000

Maintenance of Spirax Sarco 25p

Complete installation and maintenance instructions are given in IMI 3.000, a copy of which is supplied with each regulator. Available spare parts are shown on TIS 3.027 & 3.0271.

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