The sealing of the gate valve is limited by the structure, and the sealing pressure is low. It is inevitable to use a Y-shaped pipe to connect the double cylinder of the concrete pump truck and the delivery pipe during construction, and the Y-shaped pipe will cause a large pressure loss. In addition, when the gate valve is used for conveying, it is also required to install a horizontal conveying pipe section in front of the vertical conveying pipeline, and its length is 1/2 of the concrete lifting height. Because the gate is very sensitive to the backflow caused by the fluid pressure generated in the vertical direction of the concrete, forming hydraulic resistance, and this resistance will reduce the conveying height of the concrete, which is why the conveying height of the gate valve concrete pump is limited one of the main factors.
The main advantage of the S-shaped pipe valve is that the swinging nozzle is flat, easy to adjust after wear, and its sealing performance is very good, so the S-shaped pipe valve pump has a higher delivery height than the gate valve pump of the same specification. The design is based on the principle of parabola, which makes the material flow more reasonable and further reduces the resistance, and the AS-shaped pipe valve is the most widely used concrete distribution valve at present. Its main features are simple structure, smooth flow path, and small flow resistance of concrete. Good sealing performance and high pumping pressure: the height of the hopper from the ground is low, which is convenient for the concrete mixer truck to unload to the hopper; the reversing speed is fast and the noise is low.