VARISTEP, an extrapolation of LIMIPHON design, has been engineered by PARCOL in order to better prevent cavitation phenomenon, without limiting the capacity at regimes not subject to cavitation.
Main features are a radial section expansion designed both to minimize the pressure drop at last stage (the most sensitive to cavitation) and, at the same time, to limit the pressure drop at first stage.
Less stages from bottom to top of the stack, resulting in an increase of the incremental Cv along the travel. Capability to comply with the pressure drop decrease at high flow rates, usually occurring in boiler feed water applications.
The plug end close to the seating surface is labyrinth-shaped (CCF design) to provide the best pressure distribution in the clearance flow passage between plug and cage. This to prevent damage at the seat and on guiding surfaces.
All the above features make VARISTEP the ideal solution for start-up and main feedwater combined control valves.
