Oil Pilot Operated Poppet Valves are available from Wandfluh

Although no longer included in the Standard Catalog, high pressure, virtual zero leak, oil pilot operated poppet valves are still offered by Wandfluh.  Available in NG4, NG6, and NG10-NFPA sub-plate mount sizes, with pressure rating to 5000 psi, and flow rating to 21 GPM, this series offers the same operating features as the solenoid operated and air pilot operated poppet valve series. Options such as corrosion resistant coatings or materials, manual over rides, and seal materials, are also available.  See data page 1.11-7140E on the NG6 (D03) size for details and dimensions.  NG4 and NG10 pages are also readily available on our website.  Please call our office for a standard list price. 
Oil pilot operated poppet valves offer many desirable design features, ideal for certain applications such as:
1.  Sequencing Circuits:  pilot pressure will shift valve fully (to open or to close) at any psi signal that is within the catalog pressure range selected.
2.  Where remote pilot control is required, or in hard to fit locations, and where electricity or pneumatic pressure is not available,. (e.g. underground mining)
3.  Where fail safe on loss of power or signal is required.  i.e. poppet valve shuts or opens on loss of pilot signal or loss of main system pressure.
4.  Stored Hydraulic Power Banks, such as accumulators to power Diesels or Turbines for cold start-up, or on remotely located pipeline valves, or to power portable hydraulic rescue tools.
5.  For piloting larger DIN type logic valves or spool valves and virtual zero leak pilot valves are required.
6.  Where different fluids, or fluid conditions are required for pilot fluid & main system fluid.  E.G. separate reservoirs for hot and cooler fluids.

A major application advantage is that the Wandfluh oil pilot operated poppet valves allow selection of a model that will handle the available pilot pressure the system has on hand.  This is, the user does not have to add external valving or a special option to accept the available pilot pressure. He can select the model that is compatible with the pilot pressure he has! See pages 2 & 3 of data page 1.11.7140E. Min-Max curves for a variety of pilot pressures versus system pressure are shown on page 2, Dimensions for each type shown on page 3.

Ed V. Askey