TEMP. AND PRESSURE MEASURING DEVICES

1. PRESENTED BY:
ZAINA HASAN 2021-GE-08
NIMRAH ASGHAR 2021-GE-06
SADIA KHAN 2021-GE-23
INSTRUCTED BY: SIR BASIT ALI WAJID

2. PRESSURE AND TEMPERATURE
MEASURING DEVICES

3. PRESSURE MEASURING
DEVICES:
 Barometer
 Piezometer or Pressure
Tube
 Manometers
 The Bourdon Gauge
 The Diaphragm Pressure
Gauge
 Micro Manometer

4. TEMPERATURE MEASURING
DEVICES:
 Thermocouples
 Pyrometers
 Thermistors
 Thermometers
 RTD (Resistance Temperature Detector)
 Langmuir Probes

5. Heat sensitive Resistors
Measures temperature of a device
Parts:
 Protective coating
 Ceramic disc (dielectric)
 Electrode
 Hold-off-kink
 Connecting wires
THERMISTORS:

6. Washer thermistor
Construction:
Made by heating under high pressure
 Semi-conductor ceramic made from
mixtures of metallic oxides of Mn, Ni, Co,
Cu, Fe etc.
 Pressed into desired shapes
 Then baked at high temperature
Different Forms:
They are in the form of:
 Beads
 Discs
 Rods
 Washers

7. Types:
 NTC (Negative Temperature Coefficient)
Resistance decreases with increasing temperature.
 PTC (Positive Temperature Coefficient)
Resistance increases with increasing temperature.
Thermistors with high
NTC are very accurate
for measuring low
temperature especially
near 10K.
10K ≈ -263°C

8. Applications:
To monitor the temperature of:
 Motherboard of computer
 Inside incubators
 Appliances like
toasters, coffee
maker, microwave
oven etc.

9. THERMOMETER:
(Comes from Greek word “thermos” meaning
“hot” and “meter” means “to measure”)
It’s a device that measures the
temperature of a body.
History:
 Thermoscopes, the earliest
thermometers were developed by
an astronomer Galileo Galilei. It
works mainly on the Buoyancy
Principle.
 It is used to determine the capability
of an object to either sink or float.

10. Construction and Working:
It consists of glass spheres that move up and down
as the temperature changes. A rising glass sphere
indicates a fall in temperature, whereas a rise in
temperature is indicated by a falling glass sphere.

11. Parts of Thermometer:
Bulb (Temperature sensor)
Stem
Capillary tube
Scale (means of converting
this change into a numeric
value)
 Expansion chamber
MODERN THERMOMETER:
Clinical thermometer is the modern
Thermometer.
Mercury or alcohol are used as liquid.

12. MODERN THERMOMETER:
Working principle:
A thermometer works on the principle
that solids and liquids tend to expand
with temperature.
Temperature range:
It measures temperature
of a body from 35°C - 42°C

13. Different Types of
thermometer:
 Clinical Thermometer
(mercury or alcohol)
 Strip-type Thermometer
 Tympanic Thermometer
 Digital Thermometer
 Infrared Thermometer
(non-contact).

14. Other Uses:
 In Medical Field
Allows healthcare professionals
to provide accurate diagnosis
 In Meteorology
weather forecasting
 In Kitchen

15. (RTD), is a thin film device made of
platinum, which is used for measuring
temperature by measuring the resistance
of an electrical wire.
RTD (Resistance Temperature Detector):

16. Working:
When a low amount of current is passed
through the element, voltage, which is
proportional to the resistance, is
measured and converted to temperature
calibration units. The temperature is
directly proportional to the resistance of
RTD. This means when the temperature
rises, the resistance of RTD also rises and
vice versa.
RTD (Resistance Temperature Detector):

17. Applications:
 Used in automobiles to measure
the engine’s temperature.
 In communication and
instrumentation for sensing the
temperature of amplifiers.
 Also used in electronics,
military and aerospace.
RTD (Resistance Temperature Detector):

18. Langmuir Probes:
Invention:
It was invented by an American physicist Irving Langmuir.
Purpose:
A Langmuir probe is a device
that measures the temperature
of an ELECTRON.
Moreover it can also measures:
 Electron Density
 Ion Density

19. LANGMUIR PROBES:
Construction and Working:
Probe consist of an electrode with
an applied potential.
It works by inserting one or more
electrodes into a plasma, with a
constant or time-varying electric
potential between the various
electrodes or between them and the
surrounding vessel.