What is a needle valve and what are its applications?

The name needle valve came to existence due to the fact that the valve has a narrow tapered plug and port arrangement. The needle valve manufacturers made it small in size so that the control of the fluid flow can be done accurately. Needle valves can be used if the pressure heads or flow rates must be safely reduced and controlled. The valves supplied are capable to control the pressure and flow. Needle valves are linear motion valves, these valves are used in instrument systems for throttling of small volumes. 

How needle valves are constructed? 

Needle valve manufacturers made sure the valve consists of a valve body that has an orifice and a tapered stem and it can be screwed in and out to vary the orifice opening. The flow in both directions can be restricted by the help of needle valves. The preferred direction of flow is indicated by an arrow in the valve body and when the flow is in this direction then the pressure loss across the valve will be less. A needle valve with an internal check valve allows for restricted flow in one direction and free flow in the other direction. Needle valves use the stem to change the size of the orifice and this would give us the ability to compensate for changes in differential pressure in order to maintain a constant flow rate through the valve and a constant actuator speed. It would also allow establishing the desired flow rate without removing the fixed orifice.

How does a needle valve work? 

The needle valve manufacturers made the valve have spindle ends in a tapered needle, which would move into the valve seat so that it can restrict or prevent the flow of fluid through it. The in and out motion of the needle to and from the valve seat is controlled by the spindle which is operated by hand wheels. The fluid will turn ninety degrees that go through the valve and it will pass through an orifice, the orifice size can be changed by placing the cone according to the seat. 

The needle manufacturers made the needle-shaped plunger on the end of the screw so when the screw is turned the plunger will be retracted, then the flow between the plunger and the seat is possible. The fluid flow will be impeded until the plunger is retracted and the flow rate regulation is possible. Some stems which are properly threaded have slow linear movement so many turns are needed for a full flow section and this makes the needle valve used for low flow. 

Why is the needle valve crucial?

• The flow control at a low rate is very accurate

• Needle valves are smaller in size

• They can be used for throttling purpose

• Flow rates can be adjusted accurately

• Needle valves are used as bleed valves for hot water heating

• These valves can shut off easily

What are the applications of needle valves?

• The manufacturer made the valve to be used on gas bleeder lines

• These valves supplied can be used for sampling lines and for other abrasive services

• Used in Fluid power system

• The valves supplied are used for flow metering applications

• Needle valves are used in automatic combustion control systems in which accurate flow regulation is needed

• Needle valves supplied are used in constant pressure pump governors in order to reduce the effect of fluctuations in pump discharge pressure