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CHAPTER 6: MEASUREMENT OF LIQUID LEVEL ( ms 15 -32 ) - Coggle Diagram
CHAPTER 6: MEASUREMENT OF LIQUID LEVEL ( ms 15 -32 )
INTRODUCTION
To measure the quantity of liquid held in a container or vessel
WHY
affects both pressure and rate of flow in and out of the container
important to a lot of processes in modern
manufacturing plant
CLASSIFICATION
DIRECT
liquid level is directly indicated by a
simple mechanical type of device
METHOD
DIP-STICK
dipping a graduated rod in a
liquid
-Used in levelling oil car
ADVANTAGES
: ECONOMIC
DISADVANTAGES
: NOT ACCURATE
SIGHT GLASS
ADVANTAGES
: SIMPLE
DISADVANTAGES
: MANUAL RECORDING NEEDED
HOOK GAUGE
Determine in a large tank for accurate
measure of a very small changes
ADVANTAGES
: Accuracy up to +- 0.1mm
DISADVANTAGES
: Manually operated
FLOAT GAUGE
usually used are hollow metal spheres,cylindrical ceramic float or disc shaped floats of synthetic
material
ADVANTAGES
: Capable of giving continuous
DISADVANTAGES
: Proper correction is required if there is a change in
the liquid density
INDIRECT
depend on the material having a physical property which can be measured and related to level
TYPES
BUOYANCY
force produced by a submerged body which is equal to the weight of the fluid it displaces
HYDROSTATIC HEAD
force or weight produced by the height of the liquid
FORMULA
P= pgh
SONAR @ ULTRASONIC
affect in a detectable manner high frequency sound signals generated at appropriate locations near the measured material
Requires high degree of experience and skill to operate since the actual instrument is expensive
WEIGHT
force due to weight can be related very closely to level when its density is constant
W=mg
RESISTANCE
reducing overall circuit resistance in an amount proportional to level
AUTOMATIC LEVEL CONTROL SYSTEM
to provide automatic control, thus, machines, electronics or computer replace the operations of the human
