The pneumatic O-type ball valve is essentially derived from the pneumatic diaphragm control valve, which removes the valve positioner and valve limit switch on the basis of the pneumatic control valve. The stroke of the pneumatic valve can be controlled according to the pressure of the control air source to meet customer needs. Pneumatic O-ring ball valve can adjust and cut off, and is commonly used for two position control. It has a simple flow path, completely forms a straight pipe channel when fully opened, and has small pressure loss. It is especially suitable for high viscosity, suspension, pulp and other fluid occasions. Reliable sealing, small leakage, soft sealing ball valve can achieve bubble level sealing.

Type and selection of compensator
Compensator, also known as expansion joint or expansion joint, contraction joint, is mainly used to compensate for the stretching or thermal expansion and contraction caused by the pressure or temperature change of the pipeline. The compensators used today are mainly divided into natural compensators, square compensators, corrugated compensators, packing compensators, spherical compensators, as well as pull rod type corrugated compensators, hose compensators, fully buried corrugated compensators, external thrust free sleeve compensators, etc. developed from these compensators. According to the complexity of processing and manufacturing and whether it can be manufactured on site, natural compensators and square compensators are classified as pipeline type, while corrugated compensators, packing compensators and spherical compensators are classified as equipment type.
Pipe type compensator
1 Natural compensator
When the pipeline is arranged, the natural bending characteristics of the pipe position shall be used as the compensation method of this section of pipeline, which is called natural compensation. The bending part with compensation ability is called natural compensator. When designing pipelines, natural compensators should be selected as far as possible. When they cannot meet the design requirements, other types can be selected. When the bend angle is less than 150 degrees, natural compensation can be used; No natural compensator is needed to stop compensation when the temperature is greater than 150 degrees. The arm length of the naturally compensated pipeline shall not exceed 20~30m, and the bending stress shall not exceed 80 MPa.
2-square compensator
This is a kind of compensator made of high-quality seamless steel pipes into U-shaped pipe sections. When Dg ≤ 150mm, it shall be manufactured by cold bending method; When Dg>150mm, it is manufactured by hot bending, and the radius of curvature is usually (3-4) Dg. The distance between the guide bracket and the outer arm of the compensator is 40D. There are four types of square compensators, and the compensation capacity is 30~250mm. Most of them are used for ordinary heating pipe network. When they cannot be used on site, other types are selected.