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.

一般水平管與垂直管的長(cháng)度比為1:3，且不宜少于15M。當垂直高度很高時(shí)，可在垂直管分層中間增加緩沖彎頭利用彎頭中混凝土與輸送管壁間的摩擦阻力來(lái)平衡背壓，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檢驗小型混凝土泵車(chē)的管道壁厚，發(fā)現壁厚磨損較大時(shí)，應立即更換，壓力較大位置的輸送管應一起更換。當垂直向上泵送高度超過(guò)30M時(shí)，應將新的、無(wú)磨損的或管壁較厚的輸送管配置在靠近泵的一端，因為越靠近泵，管道內壓力越大。小型混凝土泵車(chē)液壓閥件的閥芯和閥體材料的不同、熱膨脹的系數也會(huì )不同，閥芯和閥體之間因熱膨脹而導致閥芯卡死的現象，致使小型混凝土泵車(chē)不能正常進(jìn)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.

工作液體的溫度升高之后，導致工作液體的黏度下降，小型混凝土泵車(chē)泵的泄漏增加，泵的實(shí)際流量就會(huì )變得有所下降;小型混凝土泵車(chē)的液壓系統發(fā)熱之后，工作液體的黏度就會(huì )下降，潤滑的性能也會(huì )降低，加快了液壓的元件的磨損，大大地縮短了小型混凝土泵車(chē)元件的使用壽命。

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.

小型攪拌機出現發(fā)熱，溫度升高的情況后，液壓系統及其元件的密封件是非常容易發(fā)生變質(zhì)的，進(jìn)而會(huì )導致其彈性變差，密封性變低，嚴重者會(huì )導致密封失效，增加了泄漏的風(fēng)險;為了保證小型攪拌機送作業(yè)的正常進(jìn)行，在使用的過(guò)程中要避免發(fā)生液壓系統發(fā)熱的現象，因為其危害是比較大的。

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.