Types of level measurement

 INDIRECT LEVEL MEASUREMENT 

1.Displacement level device

    a. torque tube

    b.flexible 

    c.spring balanced 

   d. force balanced

2. interface measurement

3.air blubbers

4.d/p cell 

5.float type 

    a. direct float operated controllers 

    b.pilot operated device

c.direct float operated valve 

e.float switches

DIRECT LEVEL MEASUREMENT

1.bob and tape 

2.sight glass

3.floats

4.gauge glass

   a. reflex glass

   b.plain glass

indirect level measurement method depends on the material having a physical property which can be measured and related to level and producing proportional out put signals for remote transmission.

Buoyancy principal.

the force produced by a submerged body which is equal to the weight of the liquid it displaces.

Hydro static head 

the force of weight produced by the height of the liquid.

Radiation 

the material measured absorbs radiation energy.

Weights 

the force due to weight can be related very close to level.

Archimedes principle.

displacement level device.