3. • DEFINITION
Pressure sensor is a electronic device
senses or monitorize the pressure in
input(gases or liquids) and converts the
data into an electronic signal
4. HISTORY:
• Galileo Galilee have been trying to measure pressure,for next three hundred
years scientists would make discoveries of pressure measurement.
• 1930-Roy Carlson- first unbonded wire Strain gauge to measure strain
inside a concrete structure
• 1954- Capacitive pressure transducer-Carl spausing. This sensor provide a
way to measure very small pressure with sufficient accuracy
• 1960-The first thin film transducer with good stability and Low hysteresis
Were developed,this technology remains today for high pressure
measurement
• 1973-William Polye-Capacitive tranducer using quartz For low pressure
ranges
6. STRAIN GAUGE
• Uses a metalwork or semiconductor
to Measure in changes in pressure
• Commonly used in Wheatstone bridge
Change in Measured voltage
Merits: small in size
stable device with Fast response
Good over-range capability
Demerits: unstable due to bonding material
sensitive temperature
7. PIEZOELECTRIC SENSOR
• When pressure is applied to crystal they
are elasticated deformed.It involves the
measurement of such deformation.
• Quartz commonly used as a sensing
crystal as it is inexpensive stable and
insensitive to temperature variation
• Merits: very high pressure Measurement
self generated signal
• Demerits: Dynamic sensing only
Temperature sensitive
8. CAPACITANCE
• This sensor is energized Electrically with high
frequency oscillation.
• Accurate pressure measurement and wide
operating range
• Commonly used in determining the level in
vessel and tank
• Merits:inaccuracy 0.01-0.2%
Linearity
• Demerits:limited over pressure capability
vibration
9. MANOMETERS
• Good example for pressure
measuring instrument
• ‘U tube manometers’ consists of U
shaped glass tube Partially filled with
a liquid
• When there are equal pressure on
both sides,the liquid level will
corresponds to zero Point on scale
10. C BOURDON TUBE
• It works on simple principle that a bend tube will
change it shape When exposed to variation in internal
and external pressure.
• Pressure applied internally,Tube straightains and
Returns it original form,when pressure is released
• Merits:Inexpensive,good sensitivity
wide operating range
• Demerits:non linear transducer
limited life when subject to Shock and
vibration
11. APPLICATIONS:
• Sensing printer ink levels
• Air flow rate in equipment
• Computer cooling systems
• Semiconductor Process equipment
• Laser measurement
• As well as clean room monitoring devices
