PRESSURE MEASUREMENT ⭐
Manometer
operating principle
Advantages
types of manometer
Disadvantages
Simple operation and construction
Good accuracy
Good sensitivity
Wide range of fluid can be use
Need of accurate leveling
Smaller operating range about 1000kN/m2
Not portable
Low cost
Suitable for low pressure application
Slow response
Large in size and bulky
The Bourdon tube works on a simple principle that a bent tube will change its shape when exposed to variations of internal and external pressure. As pressure is applied internally, the tube straightens and returns to its original form when the pressure is released.
BOURDON TUBE
Inclined manometer 
U-tube manometer 
STRAIN GAUGE
Basic Principle
Advantages
Disadvantages
Criteria for selecting a good strain gauge
What is it ?
Devices that are commonly used by engineers to measure the effect of external forces on an object.
Each strain gauge is composed of a metal foil insulated by a flexible substrate. The two leads pass a current through the gauge. As the surface of the object being measured stretches or contracts, the change in resistance is measured.
Examples
⁃ fast response
⁃ Simple setup
⁃ Small, accurate, good sensitivity
⁃ Long service life
⁃ Able to measure small placement
Examples
⁃ Temperature sensitive
⁃ Thermoelastic strain causes hysteresis
⁃ Unstable due to bonding material
Required Criteria
⁃ Able to withstand temperature difference
⁃ Hypersensitive to small materials
⁃ Able to withstand high stress
Advantages
Disadvantages
Simple construction
Slow respond to changes of pressure
Low cost
Long life
Sensitive to shocks and vibrations
Available in aide range
High accuracy
criteria required for selecting a good manometer
suitable size of dial
use acceptable range of accuracy
suitable pressure range
The principle behind a manometer gas or liquid pressure gauge is extremely simple. Hydrostatic equilibrium shows that the pressure when a liquid is at rest is equal at any point.
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Criteria
Accuracy
Pressure range
Application and measurement type
Importance of pressure measurement
Required in day-to-day situation such as maintaining optimal pressure in tubes of vehicle tires.
Serves as an indication of flowrate in many flowmeters
Helps to determining the density of liquids
Helps to determining the liquid level in tanks and containers
For ensuring safe operation condition of boiler
It is used almost in all industries.
What is pressure measurement
Atmospheric pressure, Absolute pressure, Gauge pressure, Vacuum pressure, Static pressure, Dynamic pressure, Stagnation pressure
Pressure is typically measured in units of force per unit of surface area.
Is the analysis of an applied force by a fluid on a surface