How to use check valve correctly

Selection of check valve structure

Ordinary check valve is mainly composed of spool, valve seat and spring.

Spool

Most spools are either ball valves or poppet valves.

The difference between these two structural forms is mainly reflected in the tightness, the complexity of the structure and the stability of the work.

a steel ball type b cone valve type

Steel ball type:

The structure of the straight-through check valve is simple, but the sealing is not as good as the cone valve type, and because the steel ball does not have a guide part, it is easy to generate vibration and noise during work. It is generally used in occasions where the flow rate is small.

Cone valve type:

It has the most applications. Although the structure is more complicated than the steel ball type, it has good guidance and reliable sealing.

Seat

There is always a large contact stress in the contact area of ​​the one-way valve port pipeline, so when the valve body material is lost, the steel valve seat should be added. The contact between the valve seat and the one-way valve core should be at an acute angle to ensure that the pipeline contacts. In fact, the sharp corners will deform after the force is applied, but they will deform after the force is applied and become very small surface contact, ensuring good sealing performance. Under normal circumstances, when the nominal flow is small, the contact surface of the valve seat and the one-way valve core is at a right angle, and when the nominal flow is large and the nominal pressure is high, in order to improve the oil flow and stress at the valve port, the valve seat The contact surface with the one-way spool is obtuse.

spring

The choice of spring is the choice of opening pressure

The springs are all universally designed, that is, springs of the same nominal diameter are universal.

The choice of spring only needs to consider two functions, one is to allow the oil to pass freely in the positive direction, and the other is to cause a certain pressure loss when flowing in the forward direction, that is, it is used as a back pressure valve.

The first kind of opening pressure is generally 0.03~0.05MPa; the second kind is generally 0.3-0.5MPa.

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