Rotary (Spherical) Valves

Through Rotary Valves, Fouress has brought to India over 50 years of Boving experience in design of these valves for hydro schemes the world over. Over this period the Rotary valves have undergone a lot of design changes to cope up with the water heads up to 795 meters or the lower heads associated with water distribution scheme. Used at the inlet of hydro turbines, these valves perform the function of isolating water turbines and emergency closure against turbine trips. One of the prominent advantages of these valves is that they have a clear bore when in open condition, thus offering a negligible friction head loss. While the low-pressure rotary valves are supplied with resilient rubber seals, metallic seating surfaces are provided for higher pressures. A combination of metal and resilient seals can also be specially designed. Our manufacturing range includes sizes between 400 mm to 2600 mm and operating pressure up to 80 kg/cm2 with the operation accomplished by one or two double acting hydraulic cylinders. Depending on the working parameters, we can also offer valves with alternative drive mechanism namely Electrical and Pneumatic.

Features

Design & Construction Features

The body and rotor of the valve are normally made out of Cast Carbon Steel material confirming to ASTM A 216 Gr. WCB. The valve body is made of two halves in which the spherical rotor provides through passage in open position. The sliding metallic seat is made up of high strength stainless steel casting. Metallic seat provided with sliding mechanism, renders totally free movement of rotor during operation and the seat is engaged in full closures of the valve, automatically by penstock pressure through water hydraulic control system. Penstock water pressure is applied through an operating valve on receipt of appropriate signal from turbine governor whereby sliding metallic seat travels by about 10 mm along the axis of the valve and engages with the seal on the rotor. Depending on the size of the valve, flow, working pressure etc., the seal on rotor can be offered either with a nitrile rubber or with stainless steel seal ring. Also, these valves are offered with twin seal arrangement. Wherein for normal operation, one set of seal and seat are provided on the don-stream side of the valve facing the turbine inlet. For emergency / maintenance requirements, another set of sliding seat and seal is provided on the upstream side both the seats operate on the same principle of water hydraulics and are actuated by control system when appropriated signal is given. Leak tightness and other characteristics of both the seals are identical.

Normally, these valves for turbines inlet applications are offered with hydraulic actuation through a servomotor. The actuation of this servomotor can be done by applying penstock water pressure on one side. Alternatively, the servomotor can also be actuated by the oil pressure available for the turbine governor system. Turbine inlet valve is a critical emergency device in hydro power stations, whose operation is integrated with many systems and controls. Hence this valve should render faultless response to emergency signals. If you have any requirement of this high technology product, you can count on our technical backup, manufacturing excellence and design capabilities added to the long standing experience of our principals in this field.

Material Specification