Needle valves have a slender, tapered point at the end of the valve ... While this is the most common form, valves are available that have metal - metal, plastic - plastic, or plastic - metal needles ...

Needle valves have a slender, tapered point at the end of a valve stem. Poppet valves open and close ports with a sealing device and spring. Plug or stop-cock valves are designed for both on/off and ...