What is the different between float and displacer level measurement


Thread Starter


Hi there

I need to know the different between float and displacer level measurement? What is the principle for both of them? And how to calibrate them? And what is the work mechanism for both of them?

A float does just that, it floats on top of a liquid following the surface up and down.

A displacer is usually heavier than the fluid so it doesn't float but as the fluid level rises the weight on it's supporting linkage changes due to the amount of fluid the displacer is displacing. (Archemedies Principle)

This force would be used in a strain gauge or some form of force balance system.

John Longden

Send me your email contact address and I will send you training materials covering the principles of operation and calibration procedures for each instrument.

would u plz send me the training materials and the calibration procedures,my mail id is rkchowdhury1019 [at] gmail.com.

During calibration of these displacer type LTx. we often faced a term called "desired length", Why is this required?

Eng.Abdalhadi Elyan

floats are allowed to move if level or density changes, whereas the displacers don't move or move very little. This means that the float devices follow the changes in level more closely, while the displacer follows the changes in density more accurately.

deepak dalvi

HI i am deepak

just to clear fundamentals of Float & Displacer type level measurement & transmitter on its work principle & calibration. Pls see if u can send the material.

Deepak, [email protected]

>Send me your email contact address and
>I will send you training materials
>covering the principles of operation and
>calibration procedures for each
The comprehensive answer to your question is that both floats and displacers require buoyancy force to operate, but each uses it in a different way.

The buoyancy force of the liquid acting on the float is equal to the weight of the float assembly. Therefore, the float follows the liquid level directly and, with this motion, activates the level control.

The buoyancy force acting on the displacer is much less than the weight of the displacer assembly, so the displacer becomes submerged as the liquid level rises. Since the buoyancy force is equal to the mass of the displaced liquid, as more of the displacer becomes submerged, the buoyancy force acting on the displacer increases while the displacer assembly weight remains constant. The displacer is suspended from a range spring. The result of the moving liquid level is a change in the net force acting on the range spring. With the change in force, the spring compresses or extends creating the motion necessary to activate the level control.
Dear Sir

please if you have any document about field instrument calibration send to me.

Thanking You In Advance

Best Regads
hi dear,

what if our viscosity of fluid changes? is it secure and good accuracy for our displacer?

i mean i have a fluid needs to be measured in level but my range of viscosity is wide. how can i solve this problem?