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Measuring the height of the solutions in tanks through diffrential pressure (DP) Transmitter using bubbler method.

Now problem is I have only seen the DP mounted at the base of the tanks to measure the height of the solution in the tank (open or close) and knows the theory behind it.

But now I am confronted with a setup where Bubbler type method is being used to measure the height of the liquid in tank. In this setup the air is passed to the Dip tube immersed inside the tank as well as to transmitter. So the corrosive liquid does not come in contact with the transmitter in this method.

Now in this method is it necesary to calibrate the Transmitter, or its simple enough to match the liquid height inside the tank with that of transmitter by adjusting the air flow through rotameters?

Also how to calibrate the transmitters(if required) to measure the interphase level.(By interphase level I mean, that there are two liquids inside the tank of diffrent densities, so I want to measure the the boundry of these two liquids)


Hope I am clear on my explanation ;-)
Tanks in advance

Manmeet

I think you are out of luck, the interference of two different liquids is not possible with a bubbler. You will always read the additive effect of the total head, so unless you know the level of one of the parts and can subtract from the total.........

you need a different arrangement.

Oh and yes you use the roto meter to adjust until the bubbles just start, at that point the air pressure will be equal to the head pressure.

Manmeet,

The theory and limitations of measuring level using dP and bubblers is the same. You have to assume a density of the liquid to calculate a level. As long as the density doesn't change, as might be associated with temperature change or change in the constituents in the liquid, you will be fine.

Measuring interface level using differential pressure is possible only if the total level is constant. Enter the densities of the upper and lower fluids as constants (with the same limitations as above) and the resulting calculation will yield interface level. Consider Magnetostrictive or Guided Wave Radar technologies if your total level changes. Other technologies to consider if your overall level does not change that might be more effective in your application include Rf Capacitance and Displacement.

Regards,
Bill