Characteristics of temperature sensors

From ASHRAE 1997, with permission

Category

Measurement Means

Application

Approximate Range

Uncertainty

Limitations

°F

°C

°F

°C

Liquid-in-glass thermometers

Mercury-in-glass

Temperature of gases and liquids by contact

-36/1000

-38/550

0.05 to 3.6

0.03 to 2

In gases, accuracy affected by radiation

Organic

Temperature of gases and liquids by contact

-330/400

-200/200

0.05 to 3.6

0.03 to 2

Gas thermometer

Primary standard

-456/1200

-271/665

< 0.02

< 0.01

Requires considerable skill to use

Resistance thermometers

Platinum

Precision; remote readings; temperature of fluids or solids by contact

-430/1800

-259/1000

< 0.0002 to 0.2

< 0.0001 to 0.1

High cost; accuracy affected by radiation in gases

Rhodium-iron

Transfer standard for cryogenic applications

-460/-400

-273/-243

0.0002 to 0.2

0.0001 to 0.1

High cost

Nickel

Remote readings; temperature by contact

-420/400

-250/200

0.02 to 2

0.01 to 1

Accuracy affected by radiation in gases

Germanium

Remote readings; temperature by contact

-460/-400

-273/-243

0.0002 to 0.2

0.0001 to 0.1

Thermistors

Remote readings; temperature by contact

Up to 400

Up to 200

0.0002 to 0.2

0.0001 to 0.1

Category

Measurement Means

Application

Approximate Range

Uncertainty

Limitations

°F

°C

°F

°C

Thermocouples

Pt-Rh/Pt (type S)

Standard for thermocouples on IPTS-68, not on ITS-90

32/2650

0/1450

0.2 to 5

0.1 to 3

High cost

Au/Pt

Highly accurate reference thermometer for laboratory applications

-60/1800

-50/1000

0.1 to 2

0.05 to 1

Types K and N

General testing of high temperature; remote rapid readings by direct contact

Up to 2300

Up to 1250

0.2 to 18

0.1 to 10

Less accurate than thermocouples listed above

Iron/Constantan (type J)

Same as above

Up to 1400

Up to 750

0.2 to 10

0.1 to 6

Subject to oxidation

Copper/Constantan (type T)

Same as above, especially suited for low temperature

Up to 660

Up to 350

0.2 to 5

0.1 to 3

 

Ni-Cr/Constantan (type E)

Same as above, especially suited for low temperature

Up to 1650

Up to 900

0.2 to 13

0.1 to 7

 

Beckman thermometers (metastatic)

For differential temperature in same applications as in glass-stem thermometer

10°F scale, used 32 to 212°F

0 to 100

0.01

0.005

Must be set for temperature to be measured

Bimetallic thermometers

For approximate temperature

-4/1200

-20/660

2, usually much more

1, usually much more

Time lag; unsuitable for remote use

Category

Measurement Means

Application

Approximate Range

Uncertainty

Limitations

°F

°C

°F

°C

Pressure-bulb thermometers

Gas-filled bulb

Remote testing

-100/1200

-75/660

4

2

Caution must be exercised so that installation is correct

Vapor-filled bulb

Remote testing

-25/500

-5/250

Liquid-filled bulb

Remote testing

-60/2100

-50/1150

Optical pyrometers

For intensity of narrow spectral band of high-temperature radiation (remote)

1500 and up

800 and up

30

15

 

Radiation pyrometers

For intensity of total high-temperature radiation (remote)

Any range

 

  

  

Seger cones (fusion pyrometers)

Approximate temperature (within temperature source)

1200/3600

660/2000

90

50

  

Triple points, freezing/melting points, and boiling points of materials

Standards

All except extremely high temperature

Extremely precise

For laboratory use only