Transducer List (useful for Match the following)

Sr. No	Variable	Sensor	Remark
1	Temperature	RTD(Resistance Temperature detector / Resistance Thermometer	As temp. increase resistance increase. (mostly linear)
		Thermocouple (Two metals connected together)	Active Transducer, generate voltage depends on temp. difference and material used.
		Thermistor	NTC (Negative temperature coefficient), As temp. increase resistance decrease. Non linear
		Pyrometer	Used for high temperature measurement
		LM 35 (Semiconductor IC)	Most linear Temp. sensor
		Bimetallic Thermometer	Two metal connected with different temperature coefficient
2	Flow	Variable area flow meter (rotameter)	Linear Scale, Float position change with flow, Q α h
		differential pressure (Venturi meter, Orifice plate, Dall tube, Pitot-tube)	Use Bernoulli's equation to measure the flow of fluid in a pipe.

Q α (ΔP)^0.5

Electromagnetic flow meter

Based on faraday's law (work in both direction)

Ultrasonic flow meter

Based on transit time

or Doppler effect

Turbine flow meter

Measurement volumetric flow meter

open channel flow meters

weirs and flumes for flow measurement

3

Pressure

Manometer (U Tube, inclined type, wall type)

Used for static pressure

Elastic Type Pressure gauge

(Bourdon Gauge, Bellows, Capsules, Diaphragm)

Used for static and dynamic pressure. As pressure changes, there is a mechanical displacement.

Piezoelectric Transducer

Dynamic Pressure. Electrical charges (voltage) generated as pressure changes.  

Strain Gauge

Conductor or semiconductor. (gauge factor high for semiconductor) Chang resistance

Dead weight tester

Calibration of pressure gauge

4

Low pressure

(Vaccume Measurement)

McLeod gauge

Modified manometer

Pirani Gauge

Thermal conductivity

Ionization gauge

measuring the electrical ions

knudsen gauge

5

Displacement

LVDT

Linear Displacement (linear variable differential transformer)

Capacitance

Can be used for linear and angular

RVDT

rotary variable differential transformer, angular displacement

Ultrasonic

Based on transit time

6

liquid level

Capacitance

As level changes, dielectrical constant changes

Gamma method

Radar method

7

Humidity

Hydrometer

Resistance hydrometer