Needle valve
A needle valve is a valve for the precise adjustment of a fluid flow. The needle valve contains a type of needle that can be rotated in a seat to regulate the flow. Needle valves are available in various materials such as stainless steel, steel, brass or plastic. The stainless steel needle valves are available up to very high pressures.
Ebora has manually operated, pneumatically operated and electrically operated controlled stainless steel, brass and steel needle valves.
The spindle of the needle valve can slowly increase or decrease the needle valve opening through the thread. This is because a relatively large amount of twisting is required for an adjustment. The needle of the needle valve often has a conical shape. Due to the so-called Vernier effect, it is possible to regulate accurately.
Gasketed valves are dynamically closed valves. Dynamic sealing means that a relative movement between the sealing body (spindle/ball/plug/needle) and the sealing material is possible.
Typical sealing materials are Teflon or O-rings from Perbunan, Viton, EPDM or Kalrez for standard valves, PEEK or graphite for valves for higher temperatures. These valve types are factory lubricated with silicone. This extends the life of the gasket, minimizes valve wear and reduces the required drive torque.
Applications
- laboratories
- industrial gases
- Installation and process technology
- Research and development
- aerospace industry
In these applications, precise control of liquid or gaseous media is often required and therefore this type of valve is often used.
Needle valves are typically used in flow metering applications, especially when a constant, calibrated, low flow rate must be maintained for some time, such as the stationary fuel flow in a carburettor.
Because the flow rate of the needle valve is low and many turns of the plug stem are required to fully open or close the plug stem, needle valves are not used for easy shutdown applications.
Because the opening is small and the strength advantage of the fine threaded rod is great, the needle valve is usually easy to close completely, with just "finger-tight" pressure. The spindle and/or seat of a needle valve, especially one made of brass, are easily damaged by excessive rotational force at the end of the flow.
Small, simple needle valves are often used as bleed valves in water heating applications.
