5. • Pascal’s Law
–States whenever an external
pressure is applied to any
confined fluid at rest, the
pressure is increased at every
point in the fluid by the amount
of external pressure.
6.
7.
8.
9.
10.
11. Pascal’s Law defines static fluid
pressure in 3 properties as follows:
•1. Pressure works
vertically to a wall face
12.
13. •2. The pressure at any
given point is the
same in all direction.
14.
15. •3. The pressure applied to
a part of a fluid in a closed
container is transmitted to
other parts of the fluid.
16.
17. Gas Laws
• 1. Boyle’s Law
–States the volume of a gas varies inversely
with the absolute pressure, provided the
temperature remain constant.
V1 = V2
P1 P2
18. • 2. Charles's Law
– At constant volume, the pressure of a gas varies
directly with absolute temperature.
P1 = P2
T1 T2
21. • 3. General Law of Perfect Gas
•Is a combination of Boyle’s and
Charles’s Law
P1 x V1 = P2 x V2
T1 T2
To solve for unknown P2:
P2 = P1 x V1 x T2
T1 x V2
22. •4. Dalton’s Law
–The total pressure of a
confined mixture of gasses
is the sum of the pressure
of each gasses in the
mixture.
32. • The part of the loop or
instrument that senses the value
of a process variable and sends a
corresponding predetermined
output.
• it exists in close proximity to the
process.
PROCESS ELEMENT / SENSOR
33. Pressure Elements
1. Manometers
• It is the simplest, most direct, and most accurate of all
mechanical methods. The tubes are partly filled with the
manometer liquid, which is water (for low pressure),
mercury (for high pressure) and oil (for very low pressure).
PROCESS ELEMENT / SENSOR
35. 2. Bourdon Tube
• is a pressure-sensing
element consisting of a
twisted tube of noncircular
cross section closed at one
end.
• When a process stream is
routed to the open end of the
tube, any increase in the
pressure will cause the tube
to unwind.
PROCESS ELEMENT / SENSOR
42. Pressure Elements
3. Bellows
• It is a one-piece, collapsible, seamless metallic unit that has
deep folds formed from very thin-walled tubing. The diameter of
the bellows ranges from 0.5 to 12 in. and may have as many as
24 folds.
• System pressure is applied to the internal volume of the
bellows.
PROCESS ELEMENT / SENSOR
43. 3. Bellows
• As the inlet pressure to the
instrument varies, the bellows will
expand or contract. The moving
end of the bellows is connected to
a mechanical linkage assembly.
Pressure Elements
PROCESS ELEMENT / SENSOR
45. Pressure Elements
4. Diaphragm
• A diaphragm pressure element is constructed as a
corrugated circular plate, fixed at the rim.
• When pressure is applied to either face, its center moves
but the deflection is almost un-noticeable.
• This basic construction is used for low to high pressure
applications.
PROCESS ELEMENT / SENSOR
