AVM - Needle Valve
In many cases, to regulate the flow, the only thing we can adjust is the section area of the valve passage, which can be called throttling. Altought it might sound easy, throttling is a very difficult task. Water wants to keep the same flow rate through the throttled zone, which cause local water jets and cavitation. Coping with such extreme conditions need a high tech designed anti-cavitation valve. Inline version of this premium valve type is called needle valve.
The only possible way to reduce the capacity of the water coming out under differential pressure is to restrict the flow area.
This restriction is not easy because of created water jets, cavitation conditions and the high amount of energy, which needs to be transformed.
In general all NV`s have a fixed ported zone to reach maximum flow when valve is fully open and have a balanced cylindrical throttling element which allows to reduce the flow in a controlled manner.
The cylinder is open in both ends, which enable very low operation forces, compared with the work done.