Needle valve is to press a cone, cone or ball into the center of the valve seat to seal.  Good sealing effect, suitable for working under the conditions of high pressure, small flow and small diameter; large diameter is rare, good flow adjustment performance, easy to block, and easy to lock between the valve core and valve seat under the condition of large changes in cold and heat  .  It is widely used in instruments, meters, and control equipment.

   　　Needle valve is a kind of adjustable valve, which has a wide range of uses, such as the cutting distance for flame cutting, and the knob for adjusting the flame temperature is the needle valve.  The instrument needle valve is an important part of the instrument measurement pipeline system, mainly including stop valve and ball valve, its function is to open or cut off the pipeline passage.  The valve core of the needle valve is a very pointed cone, which is inserted into the valve seat like a needle, hence the name.

    　　The needle valve has good sealing performance and long service life. Even if the sealing surface is damaged, only the wearing parts need to be replaced before it can be used continuously.  When installing the needle valve, the flow direction of the medium should be consistent with the direction of the arrow on the valve body.  Manual shut-off valves and ball valves can be installed in any position of the pipeline.

    1. The working principle of the needle valve is the same as the stop valve, except that it has a small flow cross section, usually not greater than DN10. Choose the model angle according to your needs. When used at a small flow rate, accurately control the flow rate, generally threaded connection  .  Generally speaking, the needle valve is a kind of shut-off valve. The needle valve is used for small instrument pipelines, and the shut-off valve is used for large process pipelines.

    　　2. The valve core of the needle valve is needle-shaped, while the valve core of the shut-off valve is cylindrical, and the pressure of the general needle valve is 3 kinds, 3000PSI, 6000PSI and 10000PSI, the shut-off valve is different.

    　　 Cut-off valve, also known as cut-off valve, is a forced-sealing valve, so when the valve is closed, pressure must be applied to the disc to force the sealing surface to not leak.  When the medium enters the valve from below the disc, the resistance that the operating force needs to overcome is the friction force of the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the valve stem  The diameter of the valve should be large, otherwise the valve stem will bend failure.

     　　 The stop valve is to tightly fit the valve core sealing surface and the valve seat sealing surface by pressure to prevent the medium from flowing.  It is widely used, cheap, and has good adaptability and control performance. Due to the structural characteristics, the lower the pressure, the easier the sealing effect is, so it is more used under low and medium pressure conditions.  Mostly used on process pipelines.

    　　The basis for judging whether it is needle-shaped or cut-off is whether the valve core (disc) is covered on the valve seat or inserted into the valve seat.  (Especially the needle valve of the frustum disc, the shape of the disc is very close to the stop valve)