HPE multistage ratio valves (MRV) are a range of pressure reducing valves where the outlet pressure is a fixed ratio of the inlet pressure.
These valves are designed with several internal stages, allowing them to reduce the pressure over larger ratios than is possible in one or two single-stage valves in series.
A series of paired poppet-seat sets forms the heart of the multistage ratio valves. Up to 8 poppet faces move upwards together on a spindle to open the flow passage, or move downwards together to seal on the mating seat faces.
The valve senses the higher upstream pressure on a fixed area while a piston on the top of the valve senses the downstream pressure and pushes the multi-poppet towards the mating seats.
The upward and downward forces balance ensuring that the valve maintains a fixed ratio determined by the geometrical sizes. An adjustable spring arrangement on top of the downstream pressure sensing assembly allows a small adjustment range of the ratio.
Ratio valves generally require a small flow to control pressure and are generally not tight shut-off valves. For this reason, pressure relief valves are always required to protect low-pressure piping downstream.
Key features of HPE multistage ratio valves:
- Fast reacting, inherently stable with no hunting tendency
- Downstream pressure is determined by the upstream pressure and is not dependent on the characteristics of the downstream system
- Small adjustment of ratio possible with top cap mounted spring adjuster
- Capable of operating at very high pressure ratios; even higher ratios are possible if used in conjunction with a dissipator
- Constant ratio with varying flow, resulting in a stable constant downstream pressure for a fixed inlet pressure
- Cavitation-free operation
- Cast steel valve body rated up to 25MPa
- Available in sizes from 50 to 300NB with any standard of hubs or flanges fitted
- Valves are designed to operate on mine water
Hydro Power Equipment is based in South Africa and represented in Australia by Upwey Valve & Engineering .