3 Torque of pneumatic ball valve The friction force of pneumatic ball valve depends not only on the working pressure of the medium and the diameter of the valve, but also on the form of the pneumatic ball valve, the structure of the sealing and supporting parts, and the nature of the sealing materials. In addition, in each specific structure, the friction force on the seal seat also depends on the rotation angle of the pneumatic ball valve. Torque acting under normal differential pressure: when the pneumatic ball valve is turned to 30, the maximum value appears, and when it is fully opened, it is zero. In fact, when the pneumatic ball valve is turned to 80, the pressure difference is usually much less than the maximum value. When the pneumatic ball valve is closed, the pressure difference is the largest, which gradually decreases with the increase of its opening degree. Therefore, under the condition of constant pressure, the maximum torque generation turns to 30~40; When. The work of pneumatic ball valve can be divided into two main stages.
(1) From the start of the ball to the opening of the pneumatic ball valve, the ball only acts on the friction force generated by the preload in the sealing element and the static pressure of the working medium.
(2) From the beginning of opening the valve to the stage when the ball hole completely coincides with the valve channel, the friction force generated by the static pressure difference in this stage should be added with the force caused by the liquid or gas medium. With the closing of the valve, the ball will block the through hole, so that the fluid action force on the ball will decrease and the differential pressure will increase.

Structure and application method of large and small tie rod transverse compensator
The large tie rod transverse compensator is composed of the receiver, two bellows, large tie rod and other parts. It can absorb the lateral displacement in the arbitrary plane of the pipeline system. The displacement is that the spherical nut on the pull rod rotates around the spherical washer, and the pull rod can also accept the internal pressure thrust.
The fatigue life design can be seen from the failure type and cause analysis of the bellows compensator that the planar stability, circumferential stability and corrosion resistance of the bellows are related to its displacement, i.e. fatigue life. Too low fatigue life will lead to the decline of bellows stability and corrosion resistance. According to the experiment and application experience, the fatigue life of bellows used for heat supply engineering shall not be less than 1000 times.
Bellows cannot bear load and shall be hoisted separately; In addition to the pre deformation amount of pre stretching or cold tightening required by the design, it is strictly prohibited to adjust the device deflection of the pipeline by deforming the bellows; During the installation process, welding slag is not allowed to splash on the surface of bellows and suffer from other mechanical damage; All moving elements of the bellows shall not be blocked by external components or restrict the normal operation of their moving parts.
The failure of most bellows is caused by external environmental corrosion. Therefore, when stopping the structural design of the compensator, we can consider isolating the contact between external corrosion media and bellows. For example, for the external pressure axial type compensator, the packing seal installation can be added between the outlet end ring and the outlet pipe, which is equivalent to the sleeve compensator. It can not only resist the invasion of external corrosive media, but also add a safety barrier to the bellows compensator. Even if the bellows is damaged, the compensator can also play a compensation role and prevent the bellows from failure.
The compensators include metal compensators and non-metallic compensators. According to the use of media, they can also be divided into professional anti-corrosion compensators and high-temperature compensators.
Small tie rod transverse corrugated compensator (JXH type), also known as three-dimensional corrugated compensator for pulverized coal pipeline, is a special compensator specially designed for pulverized coal pipeline. It is composed of two sections of corrugated pipe, middle receiver, small tie rod with limit nut and other parts. The corrugated pipe is made of 1Cr18Ni9Ti or SUS304 material, and adopts multi-layer one-time hydraulic forming process, which can compensate the axial, angular, transverse and synthetic displacement in all directions. The small pull rod cannot accept internal pressure thrust. After the installation of the small tie rod transverse ripple compensator, be sure to loosen the closure on the small tie rod and separate the lugs for a period of time.
Application clarification:
The small tie rod transverse type corrugated compensator can not only compensate the lateral displacement and angular displacement of the curved pipe, but also compensate the axial displacement. The axial compensation amount and the transverse compensation amount (X0, Y0) listed in the sample are used as the maximum value of the axial compensation or the transverse compensation separately. This situation should meet the following relations: X1 ≤ XoY1 ≤ YoX1, Y1 is the practical value used as the axial compensation or the transverse compensation alone. When the compensator has both axial displacement and transverse displacement, the two compensation amounts (X1, Y1) The selection of shall meet the following relationship: At this time, X1 and Y1 are the practical values with both axial displacement and transverse displacement.