• Parker Hannifin India Private Limited

Accumulators for Ball & Butterfly Valves

Ball valves and butterfly-type valves can range in size from just a few millimetres in diameter to well over one metre – and sometimes larger – and are used throughout industry. Because of the force required to reposition the valve opening, a valve actuating mechanism is required. This actuating mechanism can be a hydraulic cylinder, a pneumatic cylinder, air/oil tandem cylinder, electric motor or manual operator, depending on the application and the force required. However, in automated systems where the valve may be mounted in inaccessible locations, e.g., submerged under water, a remotely-operated hydraulic cylinder mounted directly onto the valves is often the best option. In such applications, an accumulator should be incorporated into the hydraulic circuit to ensure emergency closure of the valve in the event of power failure or hydraulic pump malfunction. The accumulator not only acts as the emergency power source, but also facilitates the unloading of the pump to conserve energy when the unit is not calling for fluid. Parker Hannifin offers an extensive range of piston and bladder accumulators for ball valve and butterfly-type valve operation. Both types operate on the hydropneumatic principle and use a dry, inert gas such as nitrogen, as the compressive medium. Accumulators are precharged with the gas to a specified pressure, typically 90% of minimum hydraulic pressure in the case of bladder accumulators and 7 bar below minimum system pressure in the case of piston accumulators. Both piston and bladder accumulators are identical in their operating principle but use different mechanisms to separate the gas from the fluid. It is this difference – and the resulting performance – which determines their suitability for different applications.