7/31/2019 Inst Presentation

1/29

7/31/2019 Inst Presentation

2/29

Parameters measured

- Temperature

- Pressure

- Flow

- Level

- pH- Brix

7/31/2019 Inst Presentation

3/29

Temperature

- Temperature Gauges

- Thermocouples

- Resistence Temperature Detectors

7/31/2019 Inst Presentation

4/29

Temperature Gauge

7/31/2019 Inst Presentation

5/29

Thermocouple

- Quick response and comparitively small time lag

- A wide range of 0 - 2300 Deg C can be measured

- Less expensive

- Low maintenance cost

7/31/2019 Inst Presentation

6/29

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

7/31/2019 Inst Presentation

7/29

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.

7/31/2019 Inst Presentation

8/29

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 )

7/31/2019 Inst Presentation

9/29

Pressure

- Pascals Law states that a confined

fluid transmits externally applied pressure

uniformly in all directions

7/31/2019 Inst Presentation

10/29

Pressure Measuring Elements

- Pressure Gauges

- Manometers

- Pressure Transmitters

7/31/2019 Inst Presentation

11/29

Pressure

Transmitter

Local LCD display

Sensor Housing

Valve Manifold

Cable entry

Rosemount SMART transmitter ( 3051 )

7/31/2019 Inst Presentation

12/29

Pressure

Diaphragm seal

Oil fill

Sensor

Capacitor plates

Lead wire

7/31/2019 Inst Presentation

13/29

Differential Pressure

7/31/2019 Inst Presentation

14/29

Pressure

7/31/2019 Inst Presentation

15/29

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

7/31/2019 Inst Presentation

16/29

Flow Measuring Elements

-Flow Transmitters

-Flow Switch

7/31/2019 Inst Presentation

17/29

Flow Transmitters

-Electro Magnetic

-Vortex

-Mass Flow

-Differential Pressure

7/31/2019 Inst Presentation

18/29

Flow

Root isolation valve

Impulse lines

Orifice plate

7/31/2019 Inst Presentation

19/29

Flow

7/31/2019 Inst Presentation

20/29

Flow

7/31/2019 Inst Presentation

21/29

Flow

High pressure Low pressure( - ) = Diff. Pr.

As per Bernoullis eqn. Flow is proportional to the sq. root

of Differential pressure

7/31/2019 Inst Presentation

22/29

Flow

Flow straightener

Strainer

Gas

separator

Turbine flowmeter

7/31/2019 Inst Presentation

23/29

Level

100

0A vessel which is

open to atmosphere.

7/31/2019 Inst Presentation

24/29

Level

100

0 A closed vessel with

atmospheric pressure.

7/31/2019 Inst Presentation

25/29

Level0 100

7/31/2019 Inst Presentation

26/29

Level

Pressure of the

vessel = x

X + hdh = Height

d = density

Transmitter measures (X + hd ) - X = hd mmWC

7/31/2019 Inst Presentation

27/29

Level

Pressure head

= h x d

Pressure head

= h x d

Resultant Diff. Pr. = zero

Seal pot

7/31/2019 Inst Presentation

28/29

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.

7/31/2019 Inst Presentation

29/29

Control path

JB

DCS

JB

Transmitter Input

OutputI/P Converter