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After midterm week 3 - Coggle Diagram
After midterm week 3
Principle of temperature measurement
Electrical
Thermocouple
5 Laws
If a third metal is inserted at one of the junctions, the e.m.f is unchanged given that both of the new junctions are at the same temp.
The law of intermediate metals
The e.m.f is not changed when a ne conductor is into the one of the metals
The law of intermediate temp.
The e.m.f depends on temp at the junction
Types
Precious metal
Type S
use in -50 to1300 Celsius
Type B
use in 1200 to 1800 Celsius
Type R
use in 0-1450 Celsius
Base Metal
Type E
use in -270 to 1000 Celsius
Type K
use in -270 to 1372 Celsius
Type J
use in -210 to 1200 Celsius
Type T
use in -248.6 to 370 Celsius
Type N
use in above 870 Celsius
Components
Metal Sheath
Thermowell
Extension/compensate wire
Plug/Connector/Accessories
Thermocouple wire
Signal conditioning component/ Readout
Resistance temperature detectors (RTDs)
Principle
Range not high as TCs.
Different from TCs because TCs read the dif.temp but RTDs can
read the temp.
The electrical resistance of metal conductors increases with
increasing temperature.
Type
Film type
Wire wound
3-wire
4-wire
2-wire
Thermistor
Semiconductor
Can detect small temperature change
Small size
Fast respone
Temp span must be narrow
Optical & Radiation
Pyrometer
Detect the emission from the object
Non-contact equipment
Less accuracy
Selecting the function depend on range of your IR testing
Follow as thermal target diameter
Thermal expansion
Bimetalic
Helix configuration
Liquid-in-glass
Partial-immersion
Total-immersion
Chemical
Using the color from the metal that changes as function of temp
Flow Measurement
Pressure-based flow meter
Principle
Accelerate flow by pass the fluid through a constriction in the pipe
Deaccelerate by bringing a portion of it to a full stop
Type
Accelerate
Segmental wedge
Venturi
Follow as Bernoulli's equation
V-cone
Orifice plate
Tap locations
Radius
Corner
Vena contracta
Pipe or Full-flow
Flange
Flow-nozzle
Pipe elbow
Deaccelerate
Target
Averaging pitot tube
Pitot tube
Annubar