This document summarizes four common types of elastic pressure measurement instruments: bourdon tube pressure gauges, diaphragm pressure gauges, bellows pressure gauges, and capsules. It describes the construction, working principle, characteristics, advantages, and disadvantages of each type. Bourdon tube pressure gauges use an oval cross-section tube that contracts or expands to transmit pressure readings. Diaphragm pressure gauges use a thin circular plate that deflects upwards under pressure. Bellows pressure gauges use an expandable and collapsible bellows element attached to a linkage.

1. Presentation Prepared by :
 Kunj Thummar (140050119517)

2. This type of instruments use primary sensing
element as some elastic material like
bourdon tube, diaphragm, bellows,
capsule,etc.
It senses pressure and converts it into
proportional mechanical signal.
What is a elastic pressure
measurement instrument ?

3. BOURDON TUBE
PRESSURE GAUGE

4. Construction :
• An elastic tube of Oval cross
section bent in a circular arc.
• One end of the end is fixed and open
for pressure sensing.
• Free end is allowed to displace
when tube contracts or expands.
• Sector attached to the free end with
a link.
• Sector is meshed with a pinion for
transmission purpose.
• A pointer is attached to the pinion
to give readings on a graduated
scale.

5. Working :

7. Characteristics
Tube material : Phosphorous – Bronze and
Alloy steel/K- monel tube.
Range : 100-700 kN/m2 for Phosphorous –
Bronze tube and 7000-630K kN/m2 for
alloy steel tube.
Advantages Disadvantages
• Simple construction
• Low cost
• High pressure range
• Good accuracy
• Susceptibility to shock
and vibration
• Gauges are subjected to
hysteresis.

8. DIAPHRAGM
PRESSURE GAUGE

9. What is a diaphragm ?
Is a thin plate of circular shape clamped firmly
around its edges.

10. Construction :
• A thin flexible diaphragm
clamped around its edges.
• One side of it is exposed to the
atmosphere and other to side where
the pressure is to be measured.
• Mechanical linkage for
transmission purpose attached at
the center of the diaphragm.
• Pointer for showing proportional
readings on the graduated scale.

11. Working :
• When the applied pressure below
the diaphragm exceeds the
atmosphere pressure the
diaphragm is deflected upwards.
• The deflection causes the link
attached to diaphragm to deflect .
• The pointer attached to the link
proportionally shows reading on a
graduated scale.

13. • small size and
moderate cost.
• Corrosion
resistant
materials can be
used.
• Good linearity.
• Can withstand
high over
pressure.
Advantages Disadvantages
• It is limited to
relatively low
pressure.
• Repairing work is
difficult.
• Lack of vibration
and shock
resistance.

14. BELLOWS PRESSURE
GAUGE

15. It is a elastic element, longitudinally
expansible and collapsible member.
What is a bellow ?

16. Construction :
• A casing is there which encloses
the bellows and spring .
• Inside the casing below is fitted
inside which there is a spring
attached.
• Bellow has a link attached to it,
which is further connected to the
sector.
• Sector meshes with a pinion,
which also has a pointer attached
to it.
• Pointer gives the reading on a
graduated scale.

17. Working :
• When pressure is sensed the free
end of the bellows compresses
against the spring force.
• This movement is transmitted to
the linkage.
• Linkage transmits it to the sector
followed by pinion.
• Lastly pointer attached to the
pinion gives us the proportionate
reading.

19. Advantages
• Simple and
rugged
construction .
• It can measure
gauge, absolute
and vacuum
pressure.
• Moderate cost.
• Good in the low
to moderate
pressure range.
Disadvantages
• Not suitable for
high pressure.
• Requires
compensation
for ambient
high pressures.
• Not suitable for
dynamic
measurement .

20. BIBLIOGRAPHY
• Text material from Fluid Mechanics by J.P. Hadiya and
H.G. Katariya (Books India Publications)
• Images from Google and Bing.
• Videos from www.youtube.com.