Applications of Mirab weight loaded – Hydraulically actuated valves can be classified as follows:
Please note that mentioned applications are the most important usage of valves and this valve can be used for other applications according to the designer’s opinion.
1- Combined pump discharge control & nonreturn valve:
Combined function in one valve Starting pumps in a controlled manner and non-return function the actuator helps to start the pump smoothly. Closing slams of the disk are prevented by means of 2 phase closing characteristics. Also, the valve can be used as an emergency shut-off valve for preventing returning water
to the pump station when a pipe burst has occurred.
2- Overflow control valve:
In this case of application, this valve can be installed at the inlet of the reservoir and can close the inlet water pipe for controlling the water level, also it can prevent water from returning in case of an inlet pipe burst occurred.
3- Turbine inlet safety valve:
Safety valve directly installed at the turbine inlet. It is used as a safety valve for quick closing in case of sudden load rejection, avoiding inadmissibly high speed (runaway speed) of the turbine and water hammer phenomena that might be created there. In a lot of plants, Weight loaded hydraulic actuators are also used in the bypass-acting quick-opening device in order to open synchronously to the closing of the inlet valve in a neutral manner as for as flow rate in concerned
4- Burst control valve:
In water piping systems, pipe bursts can happen due to natural disasters or other reasons like fire, explosion, etc. emergency hydraulic valve can be used in the system for close water flow and to protect buildings, traffic routes, pumping stations, etc.
5- Emergency drain valve (Quick opening valve):
Sometimes water drainage is necessary for the protection of systems for instance in a power plant for any reason cooling tower should be drained (to avoid freezing in winter time) in this situation emergency valve will open and would let to drain all the water.
For applications items 1, 2, 3 & 4 the valve is normally open (when the Weight is up valve is in the open situation).
In application item 5, (emergency opening) the valve is normally closed (when the Weight is up, the valve is closed)