1. UNIT-3 PRESSURE MEASUREMENT RAISED WELL MANOMETER (ENLARGED LEG MANOMETER)

2. As the liquid displaces the float also changes its position which is indicated by the pointer and scale arrangements
P1-P2 = ρm h(1+a/A)

3. MANOMETER WITH SEAL POTS

4. INCLINED TUBE MANOMETER

5. RING BALANCE MANOMETER

6. MICROMETER

7. ELASTIC TYPE PRESSURE MEASURING DEVICE
BOURDON TUBE
3 Types
1. C type
2. Spiral type
3. Helical type
BELLOWS
DIAPHRAGMS
1.Flat type
2. Corrugated type
3. Capsule type
a) Convex type
b) Nested type

8. Brass, Alloy steel, Stainlesssteel,Bronze
MATERIALS USED
Brass, Alloy steel, Stainlesssteel,Bronze
Phosphor Bronze, Berillium copper, Monel and Nickel
FACTORS TO BE CONSIDERED FOR BOURDON TUEB
Sensitivity, Non-linearity,Hysterisis,Static errors, Elevation errors,Response time, Power rating,Torque gradient constant.

9. BOURDON TUBE C-TYPE

10. Displacement of tip is
a = 0.05ap/E (r/t)0.2(x/y)0.33(x/t)3
a-Cross sectional area
p-Pressure applied
t-Thickness of tube
E- Modulus of elasticity

11. SPIRAL TYPE

12. HELIX TYPE

13. High over range capability and ratio is 10:1
HELIX TYPE
ADVANTAGES
It is stable for fluctuating pressure and it is adaptable for high pressure.
High over range capability and ratio is 10:1
By increasing the number of helical coil we can increase the range of the pressure to be measured.

14. BELLOWS

15. BELLOWS The displacment of bellow element is given by
d= 0.453pbnD21-2/Et3
p- pressure
b-Radius of each corrugations
n- No of semicircular corrugations
D-Mean diameter
-Poissions ratio
E – Modulus of elasticity

16. SPRING LOADED BELLOW

17. Deflection of bellows
d= pAb /kb+ks
p-pressure
Ab- Effective area of the bellows
Kb,Ks – Stiffness constant of bellows and spring

18. DOUBLE BELLOW DIFFERENTIAL PRESSURE GAUGE

19. DISADVANTAGES 1. It is not suited for dynamic pressure measuremnt.
2. It is required temperature compensator to reduce error due to change in ambient temperature
ADVANTAGES
It is very suited for measuring vacuum and low pressure,medium and high pressure.

20. DIAPHRAGMS
PRINCIPLE
The pressure to be measured is applied to the diaphragms depending upon the pressure deflection occurs in the surface of the diaphragms.
Deflection depends upon the thickness and diameter of the diaphragms.

21. DIAPHRAGMS

22. Pressure measurement using diaphragm

23. CAPSULE

24. ELECTRO MECHANICAL PRESSURE MEASUREMENTY (POTENTIOMETRIC TRANSDUCER)

25. POTENTIOMETRIC TRANSDUCER
ADVANTAGES
Simplicity, Ruggedness
DISADVANTAGES
-Longer size, poor frequency response, Problem on account of noise due to the movement of wiper.

26. INDUCTIVE TRANSDUCER

27. INDUCTIVE TRANSDUCER

28. Reluctance of upper = R0+k(D+d) Reluctance of lower = R0+k(D-d)
If P1>p2 – diaphragm deflects downwards
Reluctance of upper = R0+k(D+d)
Reluctance of lower = R0+k(D-d)
Inductance of the upper coil (L1) = N2/ R0+k(D+d)
Inductance of the lower coil(L2) = N2/ R0+k(D-d)
The bridge become unbalanced
e0 = ei[ R/(R+R) L2/(L1+L2)]
e0 = ei kd/2(R0+ kD)

29. LVDT TRANSDUCER

30. LVDT TRANSDUCER ADVANTAGES
1. Good sensitivity, stiff primary sensor helps to
reduce environmental effects.
2. Good frequency response, frequency
greater than 0.1MHZ
3.Linearity is good for very small
displacement.

31. DISADVANTAGES
1. Limited dynamic response
2. If displacement is high the response
becomes non-linear.

32. STRAIN GAUGES

33. STRAIN GAUGES

34. STRAIN GAUGES
ADVANTAGES
1. Good frequency response used for both static and dynamic response.
2. Good resolution even for small displacement.
3. Not affected by stray electromagnetic fields and the compensation for temperatures.

35. STRAIN GAUGES DISADVANTAGES
1. They are relatively complex to fabricate.
2. It has low output, requires signal conditioning circuit.

36. CAPACITANCE TYPE PRESSURE GAUGE

37. PIEZO ELECTRIC TRANSDUCER