Temperature Measurement

Question 1

Who invented the liquid-in-glass thermometer

when:

Answer 1

• Galileo Galilei

- 1592

Question 2

Galileo Galilei invented what in 1592

Answer 2

liquid-in-glass thermometer

Question 3

who invented the first mercury thermometer

when:

Answer 3

Athanasius Kircher

1643

Question 4

what did Athanasius Kircher invent in 1643

Answer 4

First Mercury Thermometer

Question 5

Who invented both the mercury and the alcohol thermometer with Fahrenheit scale

when:

Answer 5

Daniel Gabriel Fahrenheit

1714

Question 6

what did Daniel Gabriel Fahrenheit invented in 1714

Answer 6

mercury and alcohol thermometer with Fahrenheit scale

Question 7

He proposed a centigrade scale

when:

Answer 7

Anders Celsius

1742

Question 8

what did Anders Celsius proposed in 1742?

Answer 8

Centigrade scale

Question 9

He postulated the existence of an absolute zero

when:

Answer 9

William Thomson (Lord Kelvin)

1800’s

Question 10

He discovered the principle behind the thermocouple and the existence of the thermoelectric current

when:

Answer 10

Thomas Seebeck

1821

Question 11

He noted the temperature dependence of metals

when:

Answer 11

Sir Humphry Davy

1821

Question 12

He built the first Resistance Temperature Detector (RTD)

when: 1932

Answer 12

C.H. Meyers

1932

Question 13

what did C.H. Meyers build in 1932

Answer 13

first Resistance Temperature Detector (RTD)

Question 14

• sometimes called “Thermodynamic Temperature”
• a measure of how hot or cold something is: specifically, a measure of the average kinetic energy of the particles in a system

Answer 14

Temperature

Question 15

the minimum temperature at which all molecular motion stops

Answer 15

Absolute Zero

Question 16

Temperature measurement is also known as

Answer 16

Thermometry

Question 17

describes the process of measuring a current local temperature for immediate or later evaluation

Answer 17

Temperature Measurement

Question 18

*Categories of Temperature Measurement

Answer 18

• Thermometers
• Probes
• Non-Contact

Question 19

the basis of most present-day temperature measurements.

Answer 19

International Practical Temperature Scale

Question 20

Because of it’s toxicity and the strict governing laws, the use of mercury-in-glass thermometers has declined

Answer 20

MERCURY

Question 21

Temperature range of Mercury

Answer 21

-40 to 700 F

Question 22

If we bond these two strips of metal together, this differential growth will result in a bending motion that greatly exceeds the linear expansion. This device is called

Answer 22

Bi-metal Strip

Question 23

exploit the principle of fluid expansion to measure temperature

Answer 23

Filled-Bulb System

Question 24

4 TYPES OF FILLED BULB TEMPERATURE USED IN INDUSTRIAL APPLICATIONS

Answer 24

• Liquid Filled Systems Temperature Sensors (Class I)
• Vapor Filled Systems Temperature Sensors (Class II)
• Gas Filled Systems Temperature Sensors (Class III)
• Mercury Filled Systems Temperature Sensors (Class V)

Question 25

Here, the volumetric expansion of the liquid drives an indicating mechanism to show temperature as shown. The steel bulb, stem and indicator are completely filled under pressure with a liquid

Answer 25

Liquid Filled Systems Temperature Sensors (Class I) Temperature Range: -125F to 600F

Question 26

Filling fluid which is usually an inert hydrocarbon used in class I systems

Answer 26

XYLENE

Question 27

- uses a volatile liquid/vapor combination to generate a temperature dependent fluid expansion - this form of measurement is based on the vapor-pressure curves of the fluid and measurement occurs at the transition between the liquid and vapor phases

Answer 27

Vapor Filled Systems Temperature Sensors (Class II) Temp. Range: -40F to 32F and/or 32F to 600F

Question 28

- the change in pressure with the temperature allows us to sense the bulb’s temperature - provides a faster response than other filled devices, and as it converts temperature directly into pressure it

Answer 28

Gas Filled Systems Temperature Sensors (Class III) Temp. Range: -450 F to 1400 F

Question 29

commonly used in gas filled systems

Answer 29

NITROGEN

Question 30

- different from other liquid filled systems because of the properties of the metal - provides the widest range of operation (-40 C to 650 C)

Answer 30

Mercury Filled Systems Temperature Sensors (Class V) Temp. Range: -40 F to 1200 F

Question 31

toxic and can affect some industrial processes and is used less in filled systems

Answer 31

MERCURY

Question 32

- these low cost non-electric sensors are made from heat-sensitive fusible crystalline solids that change decisively from a solid to a liquid with a different color at a fixed temperature depending on the blend of ingredients - they are available as crayons, lacquers, pellets or labels over a wide range of temperatures from 100 to 3000 F (38 to 1650 C)

Answer 32

Bistate / Phase Change Sensors

Question 33

an assembly of two wires of unlike metals joined at one end designated the hot end. At the other end, referred to as the cold junction, the open circuit voltage is measured

Answer 33

THERMOCOUPLE

Question 34

this voltage (electromotive force) depends on the difference in temperature between the hot and cold junction and the Seebeck coefficient of the two metals

Answer 34

SEEBECK VOLTAGE

Question 35

If the junctions of a thermocouple are at the same temperature and a current is passed through the circuit of the thermocouple, HEAT is produced at one junction and ABSORBED at the other

Answer 35

PELTIER EFFECT

Question 36

the absorption or evolution of heat when current is passed through an unequally heated conductor

Answer 36

THOMSON EFFECT

Question 37

proponent of Peltier Effect

Answer 37

Jean Charles Athanase Peltier

Question 38

originally discovered the Seebeck Effect

Answer 38

Alessandro Volta

Question 39

he rediscovered the Seebeck Effect; hence its name

Answer 39

Johann Seebeck (1821)

Question 40

when two dissimilar metals with different temperatures and they’re touching, they produce an emf or voltage

Answer 40

Seebeck Effect

Question 41

the junction of two different metals of a thermocouple behaves like a ______________

Answer 41

Temperature-sensitive battery

Question 42

3 LAWS THAT APPLY TO THERMOCOUPLES

Answer 42

* Law of Intermediate Metals * Law of Homogenous Materials * Law of Intermediate Temperature

Question 43

this law is interpreted to mean that the addition of different metals to a circuit will not affect the voltage the circuit creates

Answer 43

Law of Intermediate Metals

Question 44

this law states that a thermocouple that is made with a homogenous wire cannot generate an emf, even if it is at different temperatures and thickness through out In other words, a thermocouple must be made from at least 2 different materials in order to generate a voltage

Answer 44

LAW OF HOMOGENOUS MATERIALS

Question 45

this law allows a thermocouple that is calibrated with a referende temperature to be used with another reference temperature. it allows extra wires with the same thermoelectric characteristics to be added to the circuit without affecting its total emf

Answer 45

LAW OF INTERMEDIATE TEMPERATURE

Question 46

Chromel composition

Answer 46

10% Chromium | 90% Nickel

Question 47

Constantan composition

Answer 47

55% Copper | 45% Nickel

Question 48

a temperature sensor which measures temperature using the principle that the resistance of a metal changes with temperature

Answer 48

Resistance Temperature Detector (RTD)

Question 49

the constant factor that is the basis of RTD’s

Answer 49

Temperature Coefficient of Electrical Resistance

Question 50

also a resistive device that changes its resistance predictably with temperature its benefit is a very large change in resistance per degree change in temperature, allowing very sensitive measurements over narrow spans

Answer 50

THERMISTOR

Question 51

Thermistors are devices made of ___________ . RTD’s are devices made of _____________ .

Answer 51

- metal oxide | - pure metal (usally platinum or copper)

Question 52

non contact temperature sensors that measure temperature from the amount of thermal electromagnetic radiation received from a spot on the object of measurement also called as Radiation Thermometers

Answer 52

PYROMETERS

Question 53

he invented the pyrometer

Answer 53

Josiah Wedgwood

Question 54

2 TYPES OF PYROMETERS

Answer 54

a. Radiation Pyrometers | b. Optical Pyrometers

Question 55

a noncontact radiant energy detector that measures the intensity of radiant energy and produce a signal proportional to the target temperature also referred as Infrared (IR) Thermometer

Answer 55

Radiation Pyrometers

Question 56

the physics behind radiation pyrometry is called

Answer 56

Planck’s Law of Thermal Radiation

Question 57

work on the basic principle of using human eye to match the brightness of the hot object to the brightness of the calibrated lamp filament inside the instrument

Answer 57

Optical Pyrometer