The pneumatic conveying system mainly consists of several major parts such as the feed hopper,conveying pipeline, valves,sending tank and receiving silo. The feed hopper and sending tank are connected by a series of valves with different functions. Figure shows an application example of the slide gate valve and ceramic rotary disc valve combination in the simple pneumatic conveying system.

The pneumatic ceramic rotary disc gate valve is an essential component as feeding valve in pneumatic conveying system. During material transfer, the feeding valve must shut off and provide complete sealing to isolate the sending tank from the feed hopper while maintaining internal pressure in the sending tank. The expansion joint compensates for thermal expansion and contraction and facilitates equipment disassembly. As shown in the figure, combining manual slide gate valves, pneumatic slide gate valves and ceramic rotary disc gate valves achieves the desired process functions.

1.Manual slide gate valve as maintenance valve in combination with ceramic rotary disc gate valve.
Manual slide gate valve as maintenance valve is installed between the feeding hopper and the ceramic rotary disc feeding gate valve. Its functions are as follows:①During maintenance of pneumatic conveying equipment‌: Close the manual sliding maintenance gate valve to prevent medium in the maintenance hopper from entering the conveying system or damaging the sealing parts of ceramic rotary disc gate valve .②When performing equipment maintenance or repair‌: Close the manual sliding maintenance gate valve to prevent sudden discharge of material from the maintenance hopper, facilitating maintenance and ensuring operator safety.During normal operation, the manual sliding maintenance gate valve remains open and does not require high sealing performance.
When selecting the valve model, consider the medium temperature and corrosiveness. If the medium is corrosive, both the valve body and disc should be made of stainless steel; if the medium temperature exceeds 400°C, heat-resistant steel materials should be considered.
 
2.The manual slide gate valve is used as the ash discharge valve or isolation valve.
Typically, the feeding hopper is equipped with both a discharge port and a side emergency ash discharge port. The ash discharge valve is installed at this emergency port to allow manual ash removal in case of excessive medium accumulation or equipment failure.During normal operation, the ash discharge valve remains closed and is only operated for emergency ash discharge or slag removal, hence also known as the emergency ash discharge valve.
The selection of ash discharge valves should be based on the same criteria as Manual slide maintenance gate valve, requiring consideration of media temperature and corrosiveness.

3.Pneumatic slide gate valve used as high temperature protection valve in combination with ceramic rotary disc gate valve
When selecting Pneumatic rotary disc gate valve for the pneumatic conveying system, if the material temperature is around 400°C, the feeding valve with tungsten carbide sealing surface is chosen to ensure high-temperature resistance. However, to ensure absolute reliability of the swing disc gate valve, pneumatic slide gate valve is often installed in front of the high-temperature swing disc gate valve. This setup aims to protect the sealing material of the swing disc gate valve, extends service life of feeding valve, and reduce overall equipment costs.

4.Summary
Pneumatic rotary disc gate valves have become better choice as feeding valves with advantages of pressure resistance, temperature resistance, good air tightness and long service life in pneumatic conveying systems.However, with increasingly complex application requirements and conveying materials diversify, higher demands are placed on the application of swing disc gate valves. The combined use of slide gate valves and swing disc gate valves can not only expands the application range of swing disc gate valves and extends their service life but also effectively reduces equipment costs. This analysis of the combined application of slide gate valves and swing disc gate valves is hoped to provide to provide some assistance to technical personnel in the pneumatic conveying industry.