Needle valve is a throttling valve, adjusting precision is higher. Valve needle, along the flow direction of movement, change the flow area, to truncate or flow adjusting valve. Needle valve is a kind of fine-tuning valve, the valve plug for needle, mainly used for adjusting the gas flow. Fine-tuning require valves open mouth increases gradually, from closed to open for finely adjusted.
Needle valve plug after quenching is commonly used in steel needle, and the seat is made of tin, copper and other soft materials. Asked needle valve and valve seat sealing work closely rely on the cone. Needle valve with the taper 1:50 and cone Angle of 60, cone surface after fine grinding. The valve stem and valve seat asked seal are realized by bellows.
Ball valve, evolved by the cock. It has the same rotated 90 °, the different is the cock body is ball, a round hole or channel through its axis. Spherical and opening ratio should be such, that is when the ball rotated 90 °, should all 12 needle valve present in the inlet and outlet sphere, thus cutting fluid flow.
The size of the needle valve can adjust flow, ball valve can not adjust flow; Needle valve fully open need to turn the screws round and round the handle, and only turn 90 ° to ball valve. On the shape difference is more apparent, needle valve handwheel, ball valve has a hand. In liquid, air pressure control for flow adjusting the needle valve in the pipeline, if quick truncation flow ball valve.
Any action of the valve is a kind of to cutting fluid. Depending on the valve core, can be divided into cut-off valve, gate valve, plug valve, ball valve, butterfly valve, needle valve, and so on. Pneumatic pipe type needle valve than other types of valves that can tolerate more pressure, sealed performance is good, so is generally used for small flow, high pressure gas or liquid medium sealing. Pneumatic pipe type needle valve and pressure gauge used is appropriate. The general pneumatic threaded pipe type needle valve. Nominal needle valve manufacturer pressure: PN2.5 PN4 PN6.4 PN16 PN32Mpa: nominal diameter DN5 ~ DN25 applicable medium: oil, water, gas and so on many kinds of non corrosive or corrosive medium applicable temperature: - 20 ℃ ~ + 440 ℃ -- 70 ℃ ~ 240 ℃ 540 ℃ 570 ℃ or less or less manufacturing materials such as: 20 #, 1 cr18ni9ti, 304, 316, 316 l, 12 cr1mov, etc.