The centering shaft of the semi pneumatic ball valve disc adopts the static seal between the adjusting pad and the gland. The valve stem made of stainless steel adopts a double-layer sealing structure (Figure 4), because the valve stem is only 9O. Reciprocating motion makes the packing wear less. Under normal working conditions, the opening and closing times can reach 0.6~10000 times. The valve rod torque is MF valve rod torque, the valve rod torque when N mmM0F is closed N mmMF1r friction torque between packing and valve rod, the friction torque in N mmMZc bearing, and the wall thickness of N mm valve body is calculated according to the calculation formula of ANSI B16.34 wall thickness, or selected by referring to the wall thickness data specified in JB/T 7745.

3 Bluetooth node link process The valve pneumatic device in the industrial field is usually an array. At this time, correctly completing the query and link of the Bluetooth node is the key to establish the communication between the handheld operator and the valve pneumatic device. This process is completed by the handheld operator MCU operating the main Bluetooth module through the adaptation protocol. Since there may be multiple valves with Bluetooth wireless communication function at the same time in the industrial site, the link between the handheld operator and the valve pneumatic device is divided into physical link and logical link. The logical link is a subset of the physical link. The logical link is established only after the physical link is established between the handheld operator and the valve pneumatic device, and the handheld operator receives the command to confirm the link. At this time, the handheld operator will enter the status of operating the valve pneumatic device and displaying synchronously. The valve pneumatic device can only passively receive the search and link of the handheld operator, and its upper program will give a prompt when processing the link status for the operator to judge the link status of the Bluetooth network.