Retention time in a tank

Question asked by tolisrouf on Mar 4, 2015
Latest reply on Mar 26, 2015 by pthivierge

hello everyone

This time I believe I have something really difficult!!!

There is an in-going flow in a tank and an outgoing flow out of the tank and a level set point (42-xxx.SP) which we change very often.This is our problem.We try to calculate the retention time of a thick liquor in a tank to use it in other calculations.The easiest way to calculate what is the retention time in a certain level of the tank, is to count how much time the tank needs to fill in that level. So in order to know the retention time in the tank when the level is e.g. 60% ,we have to know how much time it was needed to fill the tank to 60% level.

I created a totalizer to calculate the time needed until the tank is filled to  the higher set point (60%).This is 'fillingtime'. What we really want is another tag called 'Retentiontime' to give us the time needed to fill the tank in a different level set point.For example:

If the tank reaches 60% level in 60 minutes the 'fillingtime' totalizer shows 60 minutes.Now, if the level set point is set to 60% we want the 'retentiontime' tag  to show us 60 minutes.

If we change the level set point e.g. to 30% , we want the 'retentiontime' tag to show us how much time needed until the tank is filled to that level)

Or if it is easier we want the 'retentiontime' to show the time needed to fill the tank to the current level (if the level now is 24% to show us the time needed to fill the tank level to 24%)

I tried to make it happen but I can't.It's too difficult for me.

Does anyone have any ideas?Is there any way to do that?

Thank you