Internal fixed ratio type valves available from the South Africa-based Hydro Power Equipment are designed to reduce high upstream pressure to low downstream pressure.
The ratio of the upstream pressure to the downstream pressure is fixed and is approximately constant at all flow rates up to the maximum of the valve.
The HPE internal fixed ratio valves are suitable for mining applications where the upstream pressure is constant due to the head of water in the supply column.
Pressure ratios from 1.5:1 up to 3:1 can be provided in the same valve bodies by changing a small number of interchangeable parts. The wear parts are common across the HPE range of high pressure water control valves with proven superior durability.
HPE’s internal ratio valves operate on the principle of a high inlet pressure acting on a small area of the poppet producing a force that is balanced by an equal and opposite low downstream pressure acting on a large piston.
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’s internal ratio valves:
- Valves are very stable and do not hunt or surge
- Main valve poppet and seat are proprietary labyrinth grooved type offering proven performance in wire drawing erosion, cavitation and dirt resistance applications
- Ratio will remain within ± 0.3 at all flows
- Closer ratios can be provided by other control systems
- Valves work well at differential pressures of up to 15MPa but increasing pressure decreases life
- Internal parts are made of corrosion-resistant materials
- Seals stand up to dynamic water cylinder sealing
- Maintenance can be done in-line requiring access from one side only
- Designed to ANSI B16.34
- Valve body is rated to 25 MPa (ANSI Class 1500), but the valve pressure rating is limited by the flanges fitted
- Valve body pressure rating is reduced to 14 MPa for fatigue life up to 10 million cycles
Hydro Power Equipment is based in South Africa and represented in Australia by Upwey Valve & Engineering .