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

壓力表查看法，散裝罐車在卸料時，罐內空氣壓力為1.8～2.4公斤/平方厘米，卸料快結束時，氣壓快速下降，假如壓力表降到0～0.2公斤/平方厘米之間，則證明罐內根本卸完。

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.

卸料時刻判別法，正常罐卸料速度一般為每分種1～1.2噸，假如裝載分量為32噸，則一般需要半小時左右卸完，所以能夠依據卸料噸位計算卸料時間，這樣前25分鐘操作人員比較輕松，沒有必要長時刻緊盯壓力表或經過其它辦法查看是否卸完。

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.

空壓機聲響區分法，正常卸料時空壓機負載大，空壓機作業時宣布的聲響比較煩悶，罐體卸料結束時，空壓機負載變小，作業聲響變得洪亮。

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.

擊打罐體法，卸料過程中，用手擊打罐體，假如聲響沒有回音，則證明罐體內余料較多，還要卸一段時刻；假如罐體有回音，證明罐體內混凝土快卸完了。

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.

卸料軟管觀察法，正常卸料時，卸料軟管受流化沖擊，軟管不斷顫動，假如軟管不再顫動，也可證明罐內混凝土基本卸完了。

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.

接納塔頂揚灰區分法，正常卸料時，耗費的氣量相對較少，“料多氣少”，接納塔頂揚灰較少，卸料后期“料少氣多”，接納塔頂揚灰增多。

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.