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What I learned after mid-term week 4, 61011195 Anutida Thongchawee -…
What I learned after mid-term week 4
Pressure measurement
Force-balance pressure transmitters
Principle
Balancing a sensed differential pressure with an adjustable air pressure which becomes a pneumatic output signal
Differential pressure transmitters
Applications
Negative (vacuum) pressure
Absolute pressure
Positive (gauge) pressure
Inferring liquid level
Pressure difference
Inferring gas and liquid flow
Principle
Difference of pressure between two ports causes the diaphragm to flex from its normal resting, then translated into output signal
Electrical pressure elements
Resonant element sensor
Principle
The string's resonant frequency will indicate fluid pressure
Differential capacitance sensor
Principle
Differential capacitance
Level measurement
Hydrostatic pressure
Principle
Generating a pressure at the bottom of column owing to the action of gravity on fluid
Bubble system
Purge gas to measure hydrostatic pressure in a liquid containg vessel
Displacement
Principle
Archimedes' principle
Detecting liquid level by continuously measuring weight of object (displacer) immersed in the process liquid
Float
Principle
Reading the float's position
Echo
Principle
Measuring distance from transmitter to surface of a process material located using refleted sound waves
Types
Ultra sonic level measurement
Radar level measurement
Applications
Measuring liquid level
Measuring solid level
Level gauge (sight glasses)
Principle
Equal pressure applied to both liquid column (one column being liquid in the gauge sight glass, the other column being liquid in vessel
Weight measurement
Principle
Using multiple load cells to measure the weight of a storage vessel, the signal must be summed to produce a signal
61011195 Anutida Thongchawee