Seeking help regarding the unloading of pressure tank trucks! ! !
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Gentlemen: When a pressure tank truck loaded with C4 enters the warehouse to unload its cargo, a compressor is used to draw the gas phase from the storage tank into the tank truck, thereby pushing the liquid cargo into the storage tank; once this process is complete, the pressure inside the storage tank equals that inside the tank truck. But during operation, it is often found that after unloading, the amount of cargo unloaded exceeds the net weight indicated on the loading order; originally only 25 tons of C4 were loaded from another location, yet when weighed after unloading, the weight was 25.5 tons, an extra 500 KG. And this issue didn’t occur with just one vehicle; it was initially thought that maybe the cargo hadn’t been completely unloaded before loading it. Unloading is done more thoroughly in our warehouse, so there shouldn’t be such problems. But we always have such concerns; logically, the difference after flattening should not be that large. We would appreciate it if experts could answer this question. If the description is not clear, you can mention it online; I will add the necessary details promptly. Thank you! ! !
Were both weighings conducted internally by this unit? Or it might be brought in by external vehicles, with weighing taking place once at the external factory and once after unloading. If weighing is done at the own facility, the empty vehicle is taken there first for weight measurement, followed by filling; after unloading, another weight measurement is taken, and if there’s an excess of 500 kg, this indicates that the unloading isn’t complete. Another possibility is that the amount of gas in the tank is 500 kg, and you can use the gas law to calculate how many moles of gas are present in the full tank to see if it indeed amounts to 500 kg. I think the most likely explanation is that the unloading isn’t finished. Also, regarding weighing at another location, I’ll let you know once you reply.
We are located in a reservoir area and provide warehousing services to customers. The fully loaded vehicles are all brought in from other places for unloading. Every time the customer gives an explanation, it’s that the goods were not unloaded completely from the vehicle.
When the tank truck arrives, several measurements are taken; after unloading, another measurement is taken to ensure it’s the same as when it entered the factory.
I work in this industry; we unload propane here. Given what the original poster mentioned, the price keeps rising each time. There are several possible explanations: 1. If this happens once or twice, it might be due to high pressure before loading, and after unloading and the pressure levels out, the pressure in the tank is low – in other words, 500 kilograms of gas have been removed. It is recommended not to apply pressure after unloading the vehicle; just leave once the liquid phase has been unloaded. 2. If this happens multiple times with the same vehicle, it is recommended that you mark the scale, as it might have been tampered with.
1. Leveling after unloading is complete. The pressure after the tank truck is depressurized should not be lower than the pressure before unloading; it is not necessary to bring it down to the same level as the pressure in the storage tank. 2. During the actual unloading process, 500 kilograms should correspond to a pressure of 1 kilogram in the tank truck; in other words, the pressure after the tank truck is leveled is 1 kilogram lower than the pressure before unloading. 3. An excess of 500 kilograms was unloaded, which means that 500 kilograms more of C4 were unloaded. Because before loading, the pressure tank truck already contained material inside it. 4. As for the scale, there may also be a certain degree of error; it is recommended to contact the relevant authorities for calibration.
If this situation occurs multiple times, it is very likely due to the pressure being higher before entry into the plant than after unloading, as well as the presence of a large amount of non-condensable gas in the vapor phase of the storage tank.
I’ve counted the pressure and the quantity; it seems that when the pressure remains more or less the same before and after, it doesn’t increase much. Thank you, hero.
1. If this problem occurs with many train services, the accuracy of the weighbridge should be considered first. It is recommended to re-verify. 2. It is possible that when the vehicle was loaded upstream, there was already material inside the vehicle body, meaning it wasn’t unloaded completely. On your end, the unloading of the compressor is relatively clean, which leads to deviations. 3. The tank pressure during loading at the upstream side is much higher than that at the unloading side, but a deviation of 500 kg is a bit large. 2.3. Neither of the two should involve multiple vehicles appearing at the same time, so the most likely issue is still related to the scale.
For the first point, I’ve been doing comparisons recently; I’ve counted the pressure and the quantity, and it seems that when the pressure remains more or less the same from one period to another, it doesn’t increase much. Thank you, hero.
I’ve counted the pressure and the quantity; it seems that when the pressure remains more or less the same before and after, it doesn’t increase much. Thank you, hero.