1、 Pneumatic ball valve is a common pneumatic valve. Advantages:
1. The pneumatic ball valve is composed of a pneumatic actuator (single acting, double acting, AW type and GT type) and a ball valve. Compressed air enters the cylinder to drive the piston to rotate, and then drives the opening and closing of the ball valve through the connecting shaft, so as to cut off and adjust the medium. The pneumatic actuator is relatively fast and does not need workers to do it by themselves, which saves human resources and time to a large extent.
2. The pneumatic ball valve is evolved from the stop valve. It has the same 90 degree rotation and lifting action, but the difference is that the cock body is a sphere with a circular through hole or channel passing through its axis. The proportion of the sphere and the passage opening should be such that when the sphere rotates 90 degrees, the inlet and outlet should be all spherical, so as to cut off the flow. This type of valve can be installed at any position in the pipeline. It can be adjusted (with locator) and used for opening and closing (optional accessories). There are also many types of ball valves, which are classified according to different connection methods and materials. The details will be introduced in the article.

Analysis of the benefits of TIG welding with PTFE compensator and fixed support
The fixed support is a kind of support often used in HVAC. It plays a role in fixing and supporting the pipeline in the system. Generally, the designer sets the detailed position according to the demand. There are few rules in various standards. The compensator is used to absorb the length increase caused by the contraction of the pipeline due to the increase of temperature. Yes“ г” Type and "Z" type natural compensators and square, corrugated pipe, sleeve compensators, etc. are selected by the designer according to the expansion amount, pipe diameter and other conditions during design. However, many designers do not pay attention to this, or omit painting, or deal with it in a random way, and the location and quantity have not been carefully considered, which is not very reasonable. Gong Yi Huafeng, based on years of experience, summarized a set of methods for quickly setting fixed supports and compensators in the design of indoor 95/70 ℃ hot water heating systems. The separation examples are detailed below, hoping to play a role of throwing a brick to attract jade.
The setting of fixed supports in the design calculation system shall be after the end of pipe diameter calculation. At this time, the layout of system pipes has been completed, the pipe diameter of each section of the system has been calculated and confirmed, and the fixed supports can be arranged at the beginning.
1. Calculation of pipe thermal elongation
2. Definitely can be used without compensator“ г” Type and "Z" pipe segments are naturally compensated. As for the system described in this paper, the maximum length of straight pipe section without compensator is 33m for civil buildings and 42m for industrial buildings from the fixed point. (Pipe elongation is 40mm and 50mm respectively). In practical design, the arm length of each section is not more than 20-30m and not less than 2m. A fixed support is arranged at the top of the two natural compensation arms. “ г” Type A compensator is generally used for pipes below DN150. "Z" type compensator can be regarded as two“ г” Type compensator.
3. It is certain that the thermal elongation of local pipeline can not be stopped by natural compensation. It is certain that the PTFE compensator and the compensator set according to the calculation result can stop the natural compensation of local pipeline. Other parts are the parts where the compensator should be set. Calculate the local elongation. If multiple compensators are required for a long time, pay attention to the average setting; A fixing bracket is arranged between the two compensators. When selecting, pay attention to the sleeve compensator, which is easy to leak water and air. It is suitable to be installed in the trench, but not in the upper part of the building; The bellows compensator can be highly corrosion resistant, but the cost is high and the guide bracket is required; Square compensator requires large space for installation, but it is widely used for reliable operation. It can be selected according to the detailed conditions of the project during design.
Tungsten inert gas maintenance arc welding is a welding method that uses the arc generated between the tungsten electrode and the workpiece to heat condense the base metal and fill the welding wire under the maintenance of inert gas. It is called "TIG" welding for short.