Needle valve is a high pressure valve which consists of a body, cylinder, piston, flow regulators, shaft and gears. It cannot be used in sewage media, but can be used for any purpose as long as it is clean water media. However, main area of usage is the conditions where butterfly valve or gate valve cannot be used.
Needle valves are used where,
– Accurate flow control is required.
– Differential pressure is 16 bars or greater.
– Highly pressurized water is released to open atmosphere like dams.
– Cavitation is a problem.
– Throttling is required.
| Pressure Class | : PN10 / PN16 / PN25 / PN40 |
| Inlet and Outlet Body Material | : Ductile / SS316 |
| Cylinder Material | : Ductile / SS316 |
| Bolts & Nuts Material |
: SS316
|
| Gasket Material |
: EPDM / NBR
|
| Piston Material |
: Ductile / SS316 / Aluminum Bronze
|
| Coating |
: WRAS approved fusion bonded epoxy. 300 microns dft as standard.
|
As a parameter of geometric design, there is a water-drop shaped chamber in the middle of needle valve. As flow travels around that chamber, section of flow turns into a ring. As it continues, flow is forced to be directed at centre at outlet side of valve. Cavitation occurs and finishes inside the flow and does not create any damage on valve or other equipment. Operation of Needle Valve, By means of a mechanism, piston moves forwards and backwards inside the cylinder. When piston moves into the cylinder, flow begins through the space between body and cylinder. Valve is open at that position.
As piston approaches to body, section area of flow is reduced, velocity is increased. When piston contacts with body, valve closes and flow stops.
