The Stainless Steel needle valve plunger has a tapered end that rises and falls as the handle rotates to open or close the orifice. Figure 2 shows a cross-sectional view of the needle valve, its design, and various components. The handle (marked A in Fig. 2) is connected with the plunger, which is called the valve stem (marked B in Fig. 2). When the handle is turned, the plunger moves up or down through the thread (marked C in Figure 2). The locknut (marked D in Figure 2) prevents the plunger from loosening completely. When the plunger moves downward, the pointed (tapered) end (marked E in Figure 2) contacts the valve seat to completely seal the orifice (marked F in Figure 2). Normally, the valve seat is also tapered. This allows precise flow control.
There are a number of options and sizes for connecting needle valves to pipes or hoses via port connections on the inputs and outputs (marked G in Figure 2). For example, threads, flanges, or welds. The bonnet is connected to the valve housing (marked H in Figure 2), and the valve housing can be made of different materials such as brass or stainless steel.

Figure 2: Needle valve cross-section view and components: handle (A), stem (B), threads (C), packing nut (D), tapered end (E), orifice (F), port connection (G), and valve housing (H).

Applications:


Automatic combustion control systems

For precise flow regulation is necessary.

Most constant pressure pump governors have needle valves to minimize the effects of fluctuations in pump discharge pressure.

Used in situations where the flow must be gradually halted

Needle valves can also be used as on/off valves or for throttling service.