2. PRESSURE MEASUREMENT:
• Pressure is a crucial measurement must be made
when operating many processes.
• Industrial and lab equipment are designed to
withstand a specified work pressure.
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3. Why we need to measure the pressure ?
•In fermenter pressure influence the solubility
of gases and contribute to the maintenance
of sterility when positive pressure is present
•Factor of safety
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5. Bourdon tube pressure gauge:
•One of the standard pressure measuring
sensor
•Used as direct indicating gauge
•Relatively inexpensive
•Used for measuring the gauge pressure of
both gaseous and liquid fluids
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6. Construction and working:
• The partial coil has an elliptical cross-
section (A-A) which tends to become
circular with increasing pressure
• Because of the difference between the
internal and external radii
• Connected to fixed socket
• Pinion movements which actuates an
indicator pointer
Fig 1 : Bourdon tube pressure gauge
Courtesy: principles of fermentation technology, P.F.
STANBURY A.WHITAKAR S.J. HALL
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7. 14-09-2019 DEPARTMENT OF BIOTECHNOLOGY (BIOPROCESS ENGINEERING) 7
Construction of bourdon tube pressure gauge
8. Different type of coils:
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9. Diaphragm-type pressure sensor:
• Diaphragm pressure sensor is used for low pressure
measurement
• They cover 10mbar to 40bar
• When a vessel or pipe is to be operate under a aseptic
condition a diaphragm pressure gauge is used
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11. Working of diaphragm:
•Changes in the pressure causes the movement of
the diaphragm capsule
•The movements are monitored by a
mechanically levered pointer
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12. 14-09-2019 DEPARTMENT OF BIOTECHNOLOGY (BIOPROCESS ENGINEERING) 12
Working and difference between bourdon and diaphragm
13. Pressure control:
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Why we should control pressure inside the fermenter?
• Different working pressure are required in different
parts of a fermentation plant
• During normal operation a positive head pressure of
1.2 atmospheres is maintained in a fermenter to assist
in the maintenance of aseptic conditions.
• This pressure will obviously raised during a steam
sterilization
14. Controlling
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•The correct pressure is maintained in the
different components should be maintained by,
regulatory valves controlled by associated
pressure gauge
15. Pressure control valves:
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1. Pressure reduction valve.
2. Pressure retaining valve.
16. Pressure-reduction valves
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• Pressure reduction valves are incorporated into
pipelines when it is necessary to reduce from higher
pressure to a lower pressure
• Able to maintain the lower pressure in the downstream
side within defined limits irrespective of changes in
the inlet pressure or changes in demand for gas, stream
or water
17. Pressure-retaining valves:
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• It maintain the pressure in the pipeline upstream of
itself, and the value of itself, and the valve is designed
to open with a rising upstream pressure.
• It is constructed with a reverse action of the pressure
reduction valve
