inst presentation
TRANSCRIPT
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Parameters measured
- Temperature
- Pressure
- Flow
- Level
- pH- Brix
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Temperature
- Temperature Gauges
- Thermocouples
- Resistence Temperature Detectors
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Temperature Gauge
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Thermocouple
- Quick response and comparitively small time lag
- A wide range of 0 - 2300 Deg C can be measured
- Less expensive
- Low maintenance cost
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Thermocouple
Type Combination Ranges
KChromel - Alumel 0 - 1000 Deg C
J Iron - Constantan 0 - 750 Deg C
R Pt 13% & Rh - Pt 0 - 1600 Deg C
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Temperature
Resistance Temperature Detector :
This is made from a piece of Platinum ( Pt ) which , atstandard test conditions , has a resistance of 100 ohms at
zero degrees centigrade temperature.
That is the reason why it is also called as a Pt 100 element.
Resistance of an RTD raises by 3.9 ohms per 10 degC raise
in temperature.
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Temperature
RTD ( Field ) Control Room
If the temp. is 40 degC, the resistance of the RTD
is nearly 3.9 x 4 + 100 = 115.6 ohms.
10 ohms
10 ohms
115.6 ohmsTotal =
135.6 ohms
( 40 Deg C ) ( 90 DegC )
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Pressure
- Pascals Law states that a confined
fluid transmits externally applied pressure
uniformly in all directions
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Pressure Measuring Elements
- Pressure Gauges
- Manometers
- Pressure Transmitters
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Pressure
Transmitter
Local LCD display
Sensor Housing
Valve Manifold
Cable entry
Rosemount SMART transmitter ( 3051 )
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Pressure
Diaphragm seal
Oil fill
Sensor
Capacitor plates
Lead wire
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Differential Pressure
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Pressure
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Flow
Rate of change of velocity of a Fluid or Gas
Q = VA
Where Q is Volumetric Flow
V is Velocity of Fluid
A is Area of Cross section
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Flow Measuring Elements
-Flow Transmitters
-Flow Switch
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Flow Transmitters
-Electro Magnetic
-Vortex
-Mass Flow
-Differential Pressure
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Flow
Root isolation valve
Impulse lines
Orifice plate
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Flow
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Flow
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Flow
High pressure Low pressure( - ) = Diff. Pr.
As per Bernoullis eqn. Flow is proportional to the sq. root
of Differential pressure
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Flow
Flow straightener
Strainer
Gas
separator
Turbine flowmeter
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Level
100
0A vessel which is
open to atmosphere.
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Level
100
0 A closed vessel with
atmospheric pressure.
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Level0 100
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Level
Pressure of the
vessel = x
X + hdh = Height
d = density
Transmitter measures (X + hd ) - X = hd mmWC
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Level
Pressure head
= h x d
Pressure head
= h x d
Resultant Diff. Pr. = zero
Seal pot
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Level
If ,for example, the range of a level transmitter is
0 to 100 mm WC .
Then, after the introduction of a seal pot , the new rangewill be
0 - Hd to 100 - Hd ie., - Hd to 100 - Hd .
Where H = the distance between the upper and lower
tappings.
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Control path
JB
DCS
JB
Transmitter Input
OutputI/P Converter