This document discusses pressure measurement using manometers. It provides examples of how differential U-tube and inverted U-tube manometers work to measure pressure differences. The document explains that differential manometers can measure the pressure difference between two pipes or points, while inverted manometers use a light fluid as the manometric fluid. It also gives examples of calculation problems involving these types of manometers. The purpose is to help students understand how to use manometers to measure pressure.

1. Unit 1
Introduction, Pressure &
Pressure Measurement
Hydraulics Sem 3
Diploma Civil Engineering, GP Palanpur
Lecturer : Mr. Nihar V. Prajapati
niharprajapati1992@gmail.com

2. Lecture 6
▫ Examples of Simple Manometer
▪ Differential U-tube Manometer
▪ Inverted U-tube Manometer
▫ Examples of Differential & Inverted Manometer
Lecture Outcome
After completion of this lecture, students will be able to -
Explain the working and use of Differential and Inverted U-tube Manometer
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3. Examples on Simple Manometer
1. A simple mercury manometer is attached to a pipe carrying oil with specific
gravity 0.8. Height of the oil in the left limb is 100 mm. Difference in height of
mercury in both the limbs is 150 mm. Find the pressure in the pipe.
2. A simple mercury manometer is attached to a pipe carrying oil with specific
gravity 0.7. Height of the oil in the left limb is 120 mm. Level of mercury in the
right limb is 60 mm higher than the level of the pipe. Find the pressure in the
pipe in kilopascal.
3. Water rises to 100 cm when a pipe is attached to a piezometer. At the same
point when a simple manometer is attached, mercury level in the left limb
falls to 60 cm below pipe level. Find out the deflection in mercury.
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4. Manometers
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Differential U-tube
Manometer
Inverted U-tube
Manometer

5. Differential U-tube Manometer
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It is used to measure the difference in
pressure in two pipes/liquids or at two
different points in a same pipe.
Total Pressure in left side =
= Pressure at A + Pressure Head of liquid in pipe A in Left column
= PA + w.s1.h1
▪ Considering pressure at A in terms of height of water
= w.hA + w.s1.h1 … … (1)

6. Differential U-tube Manometer
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Total Pressure in right side =
= Pressure Head of manometric fluid + Pressure Head of liquid in pipe
B in right column + Pressure at B
= w.s.x + w.s2.h2 + w.hB ... (2)

7. Differential U-tube Manometer
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For equilibrium,
Total Pressure in left side = Total Pressure in
right side
Hence from (1) & (2)
w.hA + w.s1.h1 = w.s.x + w.s2.h2 + w.hB
hA - hB = s2.h2 - s1.h1 + s.x … m of water
▪ Pressure difference, P = PA - PB = w.(hA - hB)

8. Inverted U-tube Manometer
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Light fluid is taken as manometric fluid.
▪ Total Pressure in left side = w.hA - w.s1.h1 … … (1)
▪ Total Pressure in right side = - w.s.x - w.s2.h2 + w.hB ... (2)

9. Inverted U-tube Manometer
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For equilibrium,
Total Pressure in left side = Total Pressure in
right side
Hence from (1) & (2)
w.hA - w.s1.h1 = - w.s.x - w.s2.h2 + w.hB
hB - hA = s2.h2 - s1.h1 + s.x … m of water
Pressure difference, P = PA - PB = w.(hA - hB)

10. Examples on Diffferential Manometer
1. A differential U tube manometer is attached to two pipes A and B. In pipe
A, a liquid having 1.6 specific gravity is flowing with 120 kPa pressure.
While In pipe B, a liquid having 0.8 specific gravity is flowing with 200 kPa
pressure. Centre of pipe A is 2.5 m higher than the centre of pipe B.
Mercury level in the left side is at the same level as the centre of pipe B.
Find out the deflection in Mercury level.
2. A differential U tube manometer is attached to a pipe at two points A and
B which are at the same level. An oil of 0.8 specific gravity flows in the
pipe. If the difference of height between two surfaces of mercury is
200mm, then find the pressure difference between two points.
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11. Example on Inverted Manometer
1. Inverted differential manometer is attached to two pipes A and B
both carrying water. An oil of 0.75 specific gravity is used as
manometric fluid. Level of manometric fluid in the right Limb is 100
mm lower than that of the left limb And 50 mm higher than the
centre of pipe B. If the pressure in pipe A is equivalent to 1.5 m water
column head, find out the pressure in pipe B in kPa.
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12. Thanks!
Any questions?
You can find me at:
▪ niharprajapati1992@gmail.com
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