I am trying to use a suspended type level transmitter for measuring level of gasoline in an underground tank. The tank is horizontal cylindrical in shape & has a height (dia) of 2.7m & length 10.7m. The suspended type level transmitter basically measures the hydrostatic pressure exerted by the head of gasoline. The level transmitter has a capillary running up to ground level to compensate for atmospheric pressure. Could anyone answer if the shape of the tank has anything to do with the level head calculation?? I understand that the volume vs. level curve will not be linear, but does the shape of the tank have any effect on the linearity of the level itself?

 

While the shape of the tank has everything to do with the volume-level relationship, it has no effect on the level-head relationship.

--
Ken Irving <[email protected]>

 

On May 22, 2003, Vikram wrote:
> Could anyone answer if the shape of the tank has anything to do with the level head calculation?? I understand that the volume vs. level curve will not be linear, but does the shape of the tank have any effect on the linearity of the level itself? <

No, it hasn't. There is a well-known experiment from school physics:
Glass tubes or vessels of different shape are connected together. The level in all vessels is the same or goes to this state after some disturbance. The reason is that hydrostatic pressure depends on the level only, not the
form.

HTH

 

In my opinion, if you are measuring by weight, the shape of the tank should have nothing to do with your reading. It would be the same as putting a scale under the feet of a tank of any shape and weighing it to determine the level.

On the other hand, if you were using a level sensor like our continuous model where the float or contact with the probe determines the level then yes, you need to compensate for the round sides of the tank. We use a modified scale face for such applications or it can be done electronically with higher end models. You can see a picture a modified scale on page 28 at: http://www.almegcontrols.com/Brochure-2000.pdf

Thanks
Bob Hogg

 

I know this has nothing to do with the question, but wouldn't a radar or ultrasonic be better for measuring the tank level, especially since it is an undergound tank.

Mykel