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FLUID LEVEL MEASUREMENT

Presented byAbhishek Gupta

Bachelor of Technology [ Electronics and Instrumentation Engineering]

IET L!"#$% &&'(&)

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INTRODUCTION

Level sensors detect the level of liquids and other uids and uidized sslurries, granular materials, and powders that exhibit an upper free surfac

The level measurement can be either continuous or point values

There are many physical and application variables that aect the selectioptimal level monitoring method for industrial and commercial processes

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OLD TECHNOLOGIES

1.Sight Glass

*ight glass is the oldest and the simplest le+el measurement technology used in industrial en+ir

&, Floats

A mechanical de+ice to record its position

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DISPLACERS

The column displaces a volum

to a rise in the process uid. A buoyant force, whose magn

the product of the displaced vprocess uid density, exerts athe displacer, which brings dorequired to support it against force

This change is monitored by tlined to the transmitter, and change in force to level.

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BUBBLER

The bubbler method is used in vunder atmospheric pressure

!ry nitrogen is used. The product of the process uid

depth from the end of the dip tusurface is equal to the pressuremonitored by a pressure transdto the tube.

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-I..E/E#TIAL PRESSURET/A#*0ITTE/

The dierence between the total

bottom of the tan and the head pressure in the vessel is indicativ

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MAGNETICLEVELGAUGE

The oat in this case is a set o

permanent magnets The oat is laterally con"ned

remains close to the side wall #or this technology to wor th

and the auxiliary column shounon$magnetic materials

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CAPACITANCELEVELTRANSMITTER

%apacitance transmitters are based on the dierence in

constants & ' of process uid The basic operating principle

variance in capacitance whichthe variation in the liquid leve

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MODERN TECHNOLOGIES

Time$of$ight &T(#' measurements are used by current liquid$level

measurement techniques. The distance between the liquid level and a reference point at a senso

a transmitter placed near the top of the vessel is measured. The total travel time is measured by the electronic timing circuit Technologies lie microwaves, ultrasound and light are extremely ee

for such measurements

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ULTRASONICLEVELTRANSMITTER

)ased on the time taen by the

to travel from the uid surface toand bac

(perational frequency of these ttens of ilohertz and the transit tapproximately * ms+m.

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LASER LEVEL TRANSMITTER

!esigned for level measurements oopaque liquids and bul solids.

These sensors measure the speed olevel measurement, instead of the ssound.

ince lasers are virtually beamless false echoes, they can be directed t

spaces as small as - inches.

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RADAR LEVEL TRANSMITTER

n radar systems, the microwav

directed downward from a hornplaced at the top of a vessel.

/iquids with 0r values of 1.2 anmeasured by this method

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CONCLUSION

The use of sophisticated digital electronics is increasing the usefulness oflevel measurement and other sensors

3odern level sensors produce reliable results and are easy and lessexpensive to setup.

/evel measurement can be integrated into existing control systems thansto the enhanced communication