Control valve changes the face of water hydraulics

Edited by the Engineeringtalk editorial team May 29, 2003

The novel Janus control valve offers directional flow and pressure control for hydraulic system pressures up to 200bar - not just for water but for any corrosive low-viscosity fluid.

Over the past 15 years there have been many articles written, vast development undertaken and overwhelming levels of funding absorbed in the pursuit of equipment that will operate on water as the hydraulic fluid.

To date there are a number of companies who supply such products, but in general the designs are borne of the equivalent oil industry standards, featuring comparatively expensive material specifications and tighter manufacturing tolerances.

The result is an expensive product that restricts water hydraulics to the niche application where contamination or fire risk are the major considerations and cost is not the over riding criteria.

The Water Hydraulics Company assisted by a DTI Smart Innovation Award has succeeded in reducing the cost differential of the ranges by design.

A new range of patent-protected valves that offer both pressure and flow control are now available for general sale.

The unique Janus control valves offer directional flow and pressure control for system pressures up to 200bar - not just for water but any corrosive low-viscosity fluid.

The operating principle is a hydrostatically balanced face valve that mimics the function of a spool arrangement.

Functions not commonly available from a single valve, such as a 4/3 directional control can now be supplied.

A bolt-on pilot operated check in both single- and double-acting versions is available for load-holding applications.

Manufactured in 316 stainless steel and polymer as standard, many suitable bearing material combinations can be offered, from polymer to ceramic.

The appropriate selection is made with respect to operating pressure, system fluid, temperature and fluid contamination level.

The design is very tolerant to fluid contamination: the sealing forces generated by the operating pressure produce submicron clearances that restrict entry of contamination to the bearing interfaces.

Direct valve actuation via solenoid, pilot, hand and spring ensures that contaminants cannot clog or destroy designed pressure balances.

The ability to generate appropriate actuation forces without small pilot feed galleries ensures that contamination or scale build up will not affect the actuation of the valve.

The valve can also be configured to offer pressure control in terms of relief, reducing, unloading and overcentre.

A major feature of the design is that the section of the valve that controls the pressure differs from the surface that offers the seal.

The efficiency of the valve is not affected even if the specially selected materials are eroded due to the exceptionally high fluid velocities.

Manifold versions containing both pressure and flow control functions are available for volume applications, this offers a further cost reduction and minimises the use of expensive fittings and pipe work.

Allied with the previously developed axial piston pumps and motors and range of standard cylinders ensures that full water hydraulic system requirements can now be offered.