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We have a 300 Ton Liquid Chlorine Tank. There is a strange behavior in the loadcell output. The device can calibrated by the zero calibration, and by the load calibration. I believe both were done correctly during loadcell installation(I wasn't there that time). I suppose that due to pressure changes inside the tank, the zero had shown non-zero values when it was empty,so multiple zero calibrations has been done with time. At some point, I believe the load calibration has been done by mistake instead of zero calibration, thus overriding the initial load calibration.
Due to the fact that it is chlorine tank, it is not safe to fill water due to possible damage to tank. I don't have much experience with external weight/pressure method, but due to the fact that the tank has isolation, and cracking risk, I am unsure that it may be the right solution(perhaps pressure on the legs of the tank may work). So, until now the load calibration has been done with a man standing on the tank leg and entering his weight as a load.
Now the behavior that we observe is following:
The devices measures small weigths correctly right after the calibration with human weight. But after several minutes, the nominal output starts to decrease. Example:
1) I do the zero calibration once the tank is empty.
2) I stand on the tank leg(my weight is 60kg).
3) I enter 60kg as the load during load calibration
4) Then another person stands on the tank leg (lets say 100kg weight)
5) The device measures this weight correctly.
6) After few minutes the device value starts to fall down. The zero goes to negative values. It decreases by few kgs per minute.
7) Even when the zero is negative, the tank measures human weight correctly again.
I want to understand the following:
a) What might be reason of the constant decrease with time?A leakage inside the piping is possible, but I doub't it. Can cabling electrical problems lead to this kind of behavior?
b) Given that the small weights are measured correctly, can we state that the measurements would be correct at 50+ tons too?
What do you think? I would appreciate your help.
Due to the fact that it is chlorine tank, it is not safe to fill water due to possible damage to tank. I don't have much experience with external weight/pressure method, but due to the fact that the tank has isolation, and cracking risk, I am unsure that it may be the right solution(perhaps pressure on the legs of the tank may work). So, until now the load calibration has been done with a man standing on the tank leg and entering his weight as a load.
Now the behavior that we observe is following:
The devices measures small weigths correctly right after the calibration with human weight. But after several minutes, the nominal output starts to decrease. Example:
1) I do the zero calibration once the tank is empty.
2) I stand on the tank leg(my weight is 60kg).
3) I enter 60kg as the load during load calibration
4) Then another person stands on the tank leg (lets say 100kg weight)
5) The device measures this weight correctly.
6) After few minutes the device value starts to fall down. The zero goes to negative values. It decreases by few kgs per minute.
7) Even when the zero is negative, the tank measures human weight correctly again.
I want to understand the following:
a) What might be reason of the constant decrease with time?A leakage inside the piping is possible, but I doub't it. Can cabling electrical problems lead to this kind of behavior?
b) Given that the small weights are measured correctly, can we state that the measurements would be correct at 50+ tons too?
What do you think? I would appreciate your help.