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 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 needle valve manufacturer 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.
Needle valve type according to different can be divided into sensitive element and structure of piston, diaphragm, spring film type, bellows type and lever type, etc. Piston type needle valve work reliable, small amount of maintenance and decompression range is larger, cover an area of an area small, wide application scope. Diaphragm type needle valve work reliability is poorer, large amount of maintenance, decompression range, small volume, covers an area of big, applies only to low temperature and pressure of water and air as the medium in pipeline. Bellows type needle valve adjusting range is big, is used to working temperature t the 200 degrees of clean medium such as air and steam piping, cannot be used for the liquid pressure, more cannot be used for containing solid particles medium in pipeline. When installation usually have filter in front of the pressure reducing valve, to ensure the pressure reducing valve sensitive and reliable.
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 12 needle valve 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.
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