Piezometer U-Tube Manometer Single Column Manometer Inclined Single Column Manometer Differential Manometer U-Tube Differential Manometer Inverted U-Tube Differential Manometer

1. PRESSURE MEASURMENT
DEVICES
•Topics Covered:-
•Piezometer
•U-Tube Manometer
•Single Column Manometer
•Vertical Single Column Manometer
•Inclined Single Column Manometer
•Differential Manometer
•U-Tube Differential Manometer
•Inverted U-Tube Differential Manometer

2. PIEZOMETER
 It is a one of the simplest form of manometer used for measuring
gauge pressures. One end of this manometer is open to atmosphere
and another end is connected to the point where pressure is to ne
measured as shown in Fig. The rise of liquid gives the pressure
head at that point gives pressures head. Then pressure at A can be
measured with the help of height of liquid say h in piezometer tube
by applying following equation:-
Fig1

3. U-TUBE MANOMETER
 It is a type of manometer which consists of a glass
tube bent in U-shape on one end which is
connected to a point at which pressure is to be
measured and on the other end it remains open to
the atmosphere as shown in Fig2. This tube
generally contains liquid whose specific gravity is
greater than the specific gravity than the liquid
whose pressure is to measure.
Fig2

4. Cont....
 For Gauge Pressure – Let ‘B’ be the point at which pressure is to be
measured, whose value is p. (Datum line A-A)
Let h1 = Height of liquid above the datum line
h2 = Height of heavy liquid above the datum line
S1 = Specific gravity of light liquid
ρ1 = Density of light liquid = 1000 x S1
S2 = Specific gravity of heavy liquid
ρ2 = Density of heavy liquid = 1000 x S2
 Equation used to measure pressure:

5. Cont...
 For Vacuum Pressure – To measure
vacuum pressure, the level of level in
the manometer will be observed as
shown in Fig2 and following will be
equation to calculate pressure:

6. SINGLE COLUMN
MANOMETER
 It is a modified version of U-Tube manometer in
which a reservoir of large cross sectional area is
connected to one of the limbs of the manometer as
shown in Fig3. Reason for large reservoir is to
neglect any variation in pressure because the
change in the liquid level in the reservoir will be
very small. The height of liquid in the limb will be
used to pressure. The limb may be vertical or
inclined, thus there are following two types of
single column manometer:-
◦ Vertical Single Column Manometer
◦ Inclined Single Column Manometer

7. VERTICAL SINGLE COLUMN
MANOMETER
 Fig3 is a presentation of vertical single column manometer. Let X-X be the datum line in
the reservoir and in the right tube of manometer, when it is no connected to the pipe.
When manometer is connected to pressure, due to high pressure at A, the heavy liquid
in the reservoir will be pushed down and level will rise in the right tube.
 Let Δh = Fall of heavy liquid in reservoir
h2 = Rise of heavy liquid in right limb
h1 = Height of centre of pipe above X-X
pA = Pressure at A, which is to be measured
A = Cross sectional area of the reservoir
a = Cross-sectional area of the right tube
S1 = Specific gravity of liquid in pipe
S2 = Specific gravity of heavy liquid in reservoir
ρ1 = Density of liquid in pipe
ρ2 = Density of liquid in reservoir
 Formula for calculating pressure at point A after accumulating data from above points:
Fig3

8. INCLINED SINGLE COLUMN
MANOMETER
 It is a type of manometer which is more sensitive. Fig4 represents the inclined single
column manometer. Sensitivity in inclined single column manometer is more due to
inclination of right tube as now heavy liquid can move at more distance.
 Let L = Length of heavy liquid moved in right tube from X-X
Θ = Inclination of right tube with horizontal
Δh = Fall of heavy liquid in reservoir
h2 = Vertical rise of heavy liquid in right tube from X-X = L*sinΘ
h1 = Height of centre of pipe above X-X
pA = Pressure at A, which is to be measured
A = Cross sectional area of the reservoir
a = Cross-sectional area of the right tube
S1 = Specific gravity of liquid in pipe
S2 = Specific gravity of heavy liquid in reservoir
ρ1 = Density of liquid in pipe
ρ2 = Density of liquid in reservoir
 Following is the equation used for calculating :
Fig4

9. DIFFERNTIAL
MANOMETERS
 This type of manometers are used for
measuring the difference of pressures
between two points in a pipe or in two
different pipes. It also contains U-tube
whose ends are connected to the point
whose pressure difference is to be
measured. U-tube contains heavy liquid.
Following are two types of differential
manometer commonly used:
◦ U-Tube Differential Manometer
◦ Inverted U-Tube Differential Manometer

10. U-TUBE DIFFERENTIAL
MANOMTER
 Situation (a), two points where pressure is to be measured, A & B are at
different level and also has different specific gravity. Point A & B are
connected to a U-Tube differential manometer. Let pA and pB be the
pressure at point A & B.
 Let h = Difference of mercury level in the U-Tube
y = Distance of centre of B, from the mercury level in the right tube
x = Distance of centre of A, from the mercury level in the left tube
ρ1 = Density of liquid A
ρ2 = Density of liquid B
ρ3 = Density of heavy liquid or mercury
 Equation to calculate pressure difference between point A & B:
Fig5

11. Cont...
 Situation (b) two points A & B at same level and
contains the same liquid density ρ1. Then
following equation will be use to calculate pressure
difference between point A & B:

12. INVERTED U-TUBE
DIFFERENTIAL MANOMETER
 It is similar to U-Tube difference manometer but only difference is it consist of an
inverted U-tube, containing light liquid instead of heavy liquid. This type of
manometers are used to measure low pressure. Fig6 represents inverted u-tube
differential manometer connected to the two points A & B. Let the pressure at A is
more than pressure at B.
 Let h1 = Height of liquid in left tube below the datum line X-X
h2 = Height of liquid in right tube
h = Difference of light liquid (h1 – h2)
ρ1 = Density of liquid at A
ρ2 = Density of liquid at B
ρs = Density of light liquid
pA = Pressure at A
pB = Pressure at B
 Equation for calculating pressure difference between point A &B:
Fig6

13. THANK YOU
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