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SIP Series

For intermediate pressures

The AR Valve of our SIP series is a pump protection device particularly developed to cover applica­tions up to
250 bar with frequent plant operation at minimum flow conditions with open bypass, i.e. split flow to process and bypass line.


The most relevant application for this valve type is the boiler feed water cycle of combined cycle power plants (CCPP). In these power plants the bfw-pumps operate frequently at minimum flow conditions with pressures of 100–250 bar. The reason is the technical concept of a CCPP – for example gas turbine cooling with bfw – as well as its purpose to cover load peaks or the natural load fluctuation of renewables in the energy grid.

Operating principle

The bypass of the SIP valve is controlled by a multistage piston providing a near cavitation-free operation at any time thanks to the multistage pressure reduction at all flow rates. The piston also ensures a modulating flow control from 100 %–10 % bypass flow rate. An accelerated shut-off (1–2 sec.) at <10 % opening avoids most wear critical operation range. The wear-intensive extreme partial load range is deliberately overridden. The piston seat is separated from the pressure reduction and located at the high-pressure side. Thus, the shut-off function is optimally protected against cavitation attack. Even if cavitation would occur in the last throttle stages, the shut-off function would not be affected leaving the valve fully functional.

Advantages at a glance

  • accelerated shut-off to avoid cavitation by critical operation
  • intergrated non-return function in the bypass
  • no additional back-pressure regulation required

SIP Dimensional drawing:
main spare- and wear parts. Also available with DN4 branch with functions as for the SSV series.

Advice for a long pump and valve life

Download the brochure

Schroeder Valves is a global specialist in designing and manufacturing reliable pump protection valves.

Find out more about our AR Valves and download the PDF brochure.