SF-510
Butterfly for Nom-Slam (DN500)
Functions and Features
- ① The non-return valve can be equipped wirh a counterweight and may have an optional hydraulic damper cylinder with a unidirectional oil flow metering valve. The weight (used only on horizontal line) can be adjusted continuously along the lever and then permanently fixed to provide the minimum torque necessary to properly close the valve.
- ② The closing time of the valve can be controlled, within limits, by metering the hydraulic flow in a damper circuit.
- ③ The unidirectional oil flow control vave on the hydraulic / damper cylinder can be set from full open to full closed by adjusting the external coupling. If required it is possible to furnish an auxiliary unidirectional oil flow metering valve which be used to adjust the opening time.
- ④ The hydraulic cylinder is complete with a by-pass device and safety valve set to permit the free flow of the oil when to oil pressure is higher than 210 Bar. This abnormally high pressure can be reached only if the closing time is set too long or the hydraulic flow metering valve is not functioning. The high return flow in the butterfly valve caused by the valve closing too slowly can generate very high dynamic torque which could exceed allowable stresses if not protected by the relief valve.