In order to improve the transportation efficiency of cement and reduce the waste of resources caused by bagged cement, at present, the vast majority of cement is transported by bulk cement tanker. Because the cement tanker adopts pneumatic transportation for unloading, the unloading speed and unloading residual rate are important indicators to assess the unloading efficiency of cement tanker. It is very important to adopt correct methods to ensure that the cement in the tank is discharged as much as possible. Since the cement in the tank cannot be seen visually during unloading, some methods are needed to identify the cement unloading. Here are some simple methods to judge whether the cement is discharged or not:

1.压力表检查法，散装水泥罐车在卸料时，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，如果压力表降到0～0.2公斤/平方厘米之间，则证明罐内水泥基本卸完。

1. Pressure gauge inspection method: when the bulk cement tank truck is unloading, the air pressure in the tank is 1.8 ~ 2.4 kg / cm2. When the unloading is almost over, the air pressure drops rapidly. If the pressure gauge drops to between 0 ~ 0.2 kg / cm2, it proves that the cement in the tank is basically unloaded.

2.卸料时间判别法，正常水泥罐卸料速度一般为每分种1～1.2吨，如果水泥装载重量为32吨，则一般需要半小时左右卸完，所以可以根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，没有必要长时间紧盯压力表或通过其它方法检查是否卸完。

2. Judgment method of unloading time: the unloading speed of normal cement tank is generally 1 ~ 1.2 tons per minute. If the loading weight of cement is 32 tons, it usually takes about half an hour to complete the unloading. Therefore, the unloading time can be calculated according to the unloading tonnage. In this way, the operator is easier in the first 25 minutes. It is not necessary to keep a close eye on the pressure gauge for a long time or check whether the unloading is completed by other methods.

3.空压机声音辨别法，正常卸料时空压机负载大，空压机工作时发出的声音比较沉闷，罐体卸料结束时，空压机负载变小，工作声音变得清脆。

3. Air compressor sound discrimination method: during normal unloading, the load of the air compressor is large, and the sound generated during the operation of the air compressor is relatively dull. At the end of tank unloading, the load of the air compressor becomes smaller and the working sound becomes crisp.

4.敲打罐体法，水泥卸料过程中，可以用手敲打罐体，如果声音没有回音，则证明罐体内水泥余料较多，还要卸一段时间;如果罐体有回音，证明罐体内水泥快卸完了。

4. Knock on the tank. During the cement unloading process, you can knock on the tank by hand. If there is no echo, it proves that there is a lot of cement residue in the tank and it will take some time to unload; If the tank has an echo, it proves that the cement in the tank is almost discharged.

5.卸料软管观察法，正常卸料时，卸料软管受流化水泥冲击，软管不断抖动，如果软管不再抖动，也可证明罐内水泥基本卸完。

5. Unloading hose observation method: during normal unloading, the unloading hose is impacted by fluidized cement and the hose continues to shake. If the hose no longer shakes, it can also prove that the cement in the tank is basically unloaded.

6.水泥接收塔顶扬灰辨别法，正常卸料时，水泥消耗的气量相对较少，“料多气少”，接收塔顶扬灰较少，卸料后期“料少气多”，接收塔顶扬灰增多。

6. Identification method of ash lifting on the top of cement receiving Tower: during normal unloading, the gas consumption of cement is relatively small, "more materials and less gas", the ash lifting on the top of receiving tower is less, and the ash lifting on the top of receiving tower is more in the later stage of unloading.