6. WHAT IS TEMPERATURE?
• Temperature is one of the
most commonly used and
measured engineering
variables.
• Temperature is a thermal state of body which
distinguishes a hot body from cold body
• Scalar quantity
• Degree of hotness or coldness
7. WHAT ARE THE SCALES OF
TEMPERATURE?
Celsius
Fahrenheit
Kelvin
8. WHAT IS TEMPERATURE
MEASUREMENT?
• Temperature measurement, also
known as thermometry, describes
the process of measuring a current
local temperature for immediate or
later evaluation. Datasets consisting
of repeated standardized
measurements can be used to
assess temperature trends.
9. Historical Background
– Guillaume Amontons (1663–1705), a
French scientist, was one of the first
to explore the thermodynamic nature
of temperature. His efforts examined
the behavior of a constant volume of
air that was subject to temperature
changes.
10. – Galileo (1565–1642), who
attempted to use the volumetric
expansion of liquids in tubes as a
relative measure of temperature.
Unfortunately, this open tube
device was actually sensitive to
both barometric pressure and
temperature changes.
11. – A temperature scale proposed
by Gabriel D. Fahrenheit, a
German physicist (1686–
1736), in 1715 attempted to
incorporate body temperature
as the median point on a
scale having 180 divisions
between the freezing point
and the boiling point of water.
12. – In 1742, the Swedish
astronomer Anders
Celsius(1701–1744)
described a temperature
scale that divided the interval
between the boiling and
freezing points of water at 1
atm pressure into 100 equal
parts. The boiling point of
water was fixed as 100, and
the freezing point of water as
0.
13. The Kelvin temperature scale
was the brainchild of Belfast-
born British inventor and
scientist William Thomson —
also known as Lord Kelvin.
The Kelvin scale is
an absolute thermodynamic
temperature scaleusing as its
null point absolute zero, the
temperature at which all thermal
motion ceases in the classical
description of thermodynamics.
17. CALIBRATION
• A Calibration applies a known
input value to a measurement
system for the purpose of
observing the system output value.
• It establishes the relationship
between input and output values.
• The known value for the
calibration is called standard.
18. There are two type of
calibrations in case of
thermometers:
Melting Ice Calibration And Boiling
Water Calibration
Calibration Using a Reference
Thermometer
19. CALIBRATION OF A THERMOMETER
It involves the marking of two fixed
points:
Lower Fixed Point
Upper Fixed Point.
27. INTRODUCTION
• A liquid-in-glass thermometer is the simplest
and most commonly employed type of
temperature measurement device.
• It is one of the oldest thermometers available
in the industry.
• The principle used to measure temperature is
that of the apparent thermal expansion of the
liquid.
28. CONSTRUCTION
• 1.Bulb:
• The reservoir for containing most of the
thermometric liquid (mercury).
• 2.Stem:
• The glass tube having a capillary bore
along which the liquid moves with changes
in temperature.
• 3. Scale:
• A narrow-temperature-range scale for
reading a reference temperature .
29. Immersion Types
Total immersion:
Thermometers are designed with scales which indicate
actual temperature when the bulb and the entire liquid
column are exposed to the temperature being measured.
Partial immersion
Thermometers are designed to indicate the actual
temperature when a specified portion of its stem is
exposed to the temperature being measured.
32. ADVANTAGES
• They are comparatively cheaper than other
temperature measurement devices.
• They are handy and convenient to use.
• Unlike electrical thermometers, they do not
necessitate power supply or batteries for charging.
• They can be frequently applied in areas where there is
problem of electricity.
33. Disadvantages
1) Can not used for automatic recording.
2) Time lag in measurement.
3) Fragile construction
