In order to improve the delivery power of concrete and reduce the waste of resources caused by bagging, the vast majority of concrete is now transported by bulk tank trucks, because the tank trucks use pneumatic conveying to discharge, the discharge speed and discharge remaining rate are the important objectives to investigate the discharge power of tank trucks. It is very important to choose the right way to ensure that the tank of self loading mixer is unloaded as much as possible. Because the tank can not be seen directly during unloading, it is necessary to use some methods to judge the unloading condition. Here are some simple methods to judge whether the concrete has been unloaded

压力表查看法，散装罐车在卸料时，罐内空气压力为1.8～2.4公斤/平方厘米，卸料快结束时，气压快速下降，假如压力表降到0～0.2公斤/平方厘米之间，则证明罐内根本卸完。

According to the pressure gauge, when the bulk tanker is discharging, the air pressure in the tank is 1.8-2.4 kg / cm2. When the discharging is almost finished, the air pressure drops rapidly. If the pressure gauge drops to 0-0.2 kg / cm2, it proves that the tank is completely discharged.

卸料时刻判别法，正常罐卸料速度一般为每分种1～1.2吨，假如装载分量为32吨，则一般需要半小时左右卸完，所以能够依据卸料吨位计算卸料时间，这样前25分钟操作人员比较轻松，没有必要长时刻紧盯压力表或经过其它办法查看是否卸完。

Discharge time discrimination method, the normal tank discharge speed is generally 1 ~ 1.2 tons per minute, if the loading component is 32 tons, it generally takes about half an hour to complete the discharge, so the discharge time can be calculated according to the discharge tonnage, so the first 25 minutes of the operator is relatively easy, there is no need to keep a close eye on the pressure gauge or through other methods to check whether the discharge is completed.

空压机声响区分法，正常卸料时空压机负载大，空压机作业时宣布的声响比较烦闷，罐体卸料结束时，空压机负载变小，作业声响变得洪亮。

According to the method of distinguishing the sound of air compressor, the load of air compressor is large during normal discharge, and the sound announced during the operation of air compressor is boring. At the end of tank discharge, the load of air compressor becomes smaller and the operation sound becomes loud.

击打罐体法，卸料过程中，用手击打罐体，假如声响没有回音，则证明罐体内余料较多，还要卸一段时刻；假如罐体有回音，证明罐体内混凝土快卸完了。

In the method of hitting the can body, during the unloading process, hit the can body by hand. If there is no echo, it proves that there is more material left in the can body, and it needs to be unloaded for a period of time; If there is an echo in the tank, it proves that the concrete in the tank is almost finished.

卸料软管观察法，正常卸料时，卸料软管受流化冲击，软管不断颤动，假如软管不再颤动，也可证明罐内混凝土基本卸完了。

According to the observation method of discharge hose, during normal discharge, the discharge hose is impacted by fluidization, and the hose vibrates continuously. If the hose no longer vibrates, it can also prove that the concrete in the tank is basically discharged.

接纳塔顶扬灰区分法，正常卸料时，耗费的气量相对较少，“料多气少”，接纳塔顶扬灰较少，卸料后期“料少气多”，接纳塔顶扬灰增多。

According to the classification method of accepting the dust lifting from the top of the tower, the gas consumption is relatively small during the normal discharge, "more materials and less gas", less dust lifting from the top of the tower, and "less materials and more gas" at the later stage of discharge, more dust lifting from the top of the tower.