When the vertical height of pipe laying of small mixer is high or limited by the site, it is difficult to balance the back pressure only by setting horizontal pipe, then it is better to set a cannula (also known as plug valve pipe) between the conical pipe and the straight pipe of the conveying pipe, and close the pipe when the pumping is stopped to prevent concrete backflow. When the vertical height is low, a certain length of horizontal pipe is set between the lower end of the vertical pipe and the small mixer, and the friction resistance between the concrete in the horizontal pipe and the wall of the conveying pipe is used to balance the back pressure.
一般水平管与垂直管的长度比为1:3，且不宜少于15M。当垂直高度很高时，可在垂直管分层中间增加缓冲弯头利用弯头中混凝土与输送管壁间的摩擦阻力来平衡背压，以防止混凝土回流。
Generally, the length ratio of horizontal pipe to vertical pipe is 1:3, and should not be less than 15m. When the vertical height is very high, the buffer elbow can be added in the middle of the vertical pipe layer, and the friction resistance between the concrete in the elbow and the wall of the conveying pipe can be used to balance the back pressure to prevent the concrete backflow.
需要格外注意的是需要定期检验小型混凝土泵车的管道壁厚，发现壁厚磨损较大时，应立即更换，压力较大位置的输送管应一起更换。当垂直向上泵送高度超过30M时，应将新的、无磨损的或管壁较厚的输送管配置在靠近泵的一端，因为越靠近泵，管道内压力越大。小型混凝土泵车液压阀件的阀芯和阀体材料的不同、热膨胀的系数也会不同，阀芯和阀体之间因热膨胀而导致阀芯卡死的现象，致使小型混凝土泵车不能正常进行工作。
Special attention should be paid to the regular inspection of the pipe wall thickness of the small concrete pump truck. When the wall thickness is worn out, it should be replaced immediately, and the delivery pipe at the position with higher pressure should be replaced together. When the vertical upward pumping height exceeds 30m, the new, wear-free or thick pipe wall delivery pipe should be arranged at the end close to the pump, because the closer to the pump, the greater the pressure in the pipeline. The material of valve core and valve body of small concrete pump truck are different, and the coefficient of thermal expansion is also different. The phenomenon of valve core sticking caused by thermal expansion between valve core and valve body causes small concrete pump truck not to work normally.
工作液体的温度升高之后，导致工作液体的黏度下降，小型混凝土泵车泵的泄漏增加，泵的实际流量就会变得有所下降;小型混凝土泵车的液压系统发热之后，工作液体的黏度就会下降，润滑的性能也会降低，加快了液压的元件的磨损，大大地缩短了小型混凝土泵车元件的使用寿命。
When the temperature of the working liquid rises, the viscosity of the working liquid decreases, and the leakage of the small concrete pump truck increases, and the actual flow rate of the pump will decrease; After the hydraulic system of the small concrete pump truck is heated, the viscosity of the working fluid will decrease, and the lubrication performance will also be reduced, which will speed up the wear of the hydraulic components and greatly shorten the service life of the components of the small concrete pump truck.
小型搅拌机出现发热，温度升高的情况后，液压系统及其元件的密封件是非常容易发生变质的，进而会导致其弹性变差，密封性变低，严重者会导致密封失效，增加了泄漏的风险;为了保证小型搅拌机送作业的正常进行，在使用的过程中要避免发生液压系统发热的现象，因为其危害是比较大的。
When the small mixer is heated and the temperature rises, the sealing parts of the hydraulic system and its components are very easy to deteriorate, which will lead to poor elasticity and low sealing. In serious cases, it will lead to seal failure and increase the risk of leakage; In order to ensure the safe and normal operation of small mixer, the phenomenon of heating of hydraulic system should be avoided in the process of use, because its harm is relatively large.
