Exp 4-Process Instrument

Experiment 4: Level Measurement & Calibration System

UNIVERSITI KUALA LUMPUR

MALAYSIAN INSTITUTE OF CHEMICAL & BIOENGINEERING TECHNOLOGY

CLB 21103

PROCESS INSTRUMENTATION

BACHELOR OF CHEMICAL ENGINEERING

TECHNOLOGY

EXPERIMENT 4

Level Measurement & Calibration

SEMESTER

January 2013


EXPERIMENT 4

LEVEL MEASUREMENT & CALIBRATION

1.0 EXPERIMENT PROCEDURES

1.1 Plant Start-up Procedures

1 Fill-up water in Tank T2 up to its overflow level. Make sure that drain valve is fully

closed.

2 At the front panel, make sure the heater and pump (P) are off.

3 Then switch ON the main power supply located at the front panel. The panel

instruments should all lit up.

4 Check that the pump suction valve and all pump discharge valves are fully open.

5 Open one turn of the pump by-pass valve (BV) first before starting the pump (P).

After pump start-up, close BV fully. This is a good practice to avoid any hydraulic

shock to the pump (P).

Note: During the experiment, if the water of tank T2 is at the low level, the level switch

(LS) will automatically switch off the heaters and pump (P). In this case, top up

more water into tank T2 from external water supply.

1.2 Experiment 1: Level Measurement

(Tank T1 as OPEN, Heater OFF)

1. Refer to the start-up procedures and check that the procedures are done before the

experiment is carried out.

2. For tank T1, fully open top vent (V) and overflow manual valves.

3. Make sure bottom gate valve is fully open and globe valve is fully closed.

4. Make sure air inlet manual isolation valve is closed (with 900 position at the air supply

inlet tubing). The top space of tank T1 is at atmospheric pressure, as monitored by the

pressure gauge (PG).

5. Open one turn of the pump by-pass valve (BV) first before starting the pump (P)

6. Start pump (P) by pressing the green pushbutton at the front panel.

7. After pump start-up, close the pump by-pass valve (BV).


8. Adjust the flowrate by using Variable Area Flowmeter (FI) to about 2.5m3/hr. Let

the water circulate throughout tanks T1 and T2.

9. At the sight millimetre scale (LG), observe the level in tank T1 rise until it overflows

to make sure that both of the wet legs at the Differential Pressure/Level Transmitter

(LT) is filled with water.

10. Close the manual discharge gate valve at tank T1. Stop the pump (P).

11. Run the Experiments:

Suggested Level: 700mm

Open the bottom globe valve of tank T1 to allow the water in tank T1 to

flow into tank T2 until the level at LG reads about 700mm. Close the

bottom globe valve.

Take 2 set of reading and record in the Table 1

Continue measure the level from 600 mm until 300 mm.


(Tank T1 as CLOSED Tank, Heater OFF)


experiment is carried out

2. Check that tank T1 is still operated as an OPEN tank.

Make sure that the top vent (V) and overflow manual valve are fully open.

Make sure that the manual discharge valves i.e. bottom gate valve is fully open

and globe valve is fully closed.

The pressurising air inlet manual isolation valve handle is 900 to the air supply

inlet tubing.

3. Open one turn of the pump by-pass valve (BV) first before starting the pump (P).

Start pump (P) by pressing the green pushbutton at the front panel. After pump start-

up, check that the pump by-pass valve (BV) is fully closed.

4. Adjust the flowrate by using Variable Area Flowmeter (FI) to about 2.5m3/hr. Let the

water circulate throughout tanks T1 and T2.





7. Open the bottom globe valve of tank T1 to allow the water in tank to flow out into tank

T2 until the level at LG reads to about 750mm. Close the bottom globe valve.

8. Then pressurise tank T1 as detailed below:


Fully CLOSE the vent (V), overflow, bottom gate valve and globe valves of

tank T1.

Pressurise the top space of tank T1 by opening the pressurising air inlet manual

isolation valve (with the valve handle in parallel to the air supply inlet tubing)

located next to the AS for air to flow into the top of tank T1.

Check that the pressure at pressure gauge is between 2.50 – 3.00 psig.

Note: Tank T1 is now a closed tank under pressure.

9. Run the Experiments




bottom globe valve.

Take 2 set of reading and record in the Table 2

Continue measure the level from 600mm until 300 mm.

Open vent and overflow valve after experiment finish to release the

pressure in tank T1


(Tank T1 as OPEN Tank, Heater ON)



2. For tank T1, fully open top vent (V) and overflow manual valves.

3. Make sure bottom gate valve is fully open and globe valve is fully closed.

4. Make sure air inlet manual isolation valve is closed (position 900 at the air supply inlet

tubing). The top space of tank T1 is at atmospheric pressure, as monitored by the

pressure gauge (PG).

5. Open one turn of the pump by-pass valve (BV) first before starting the pump (P).

Start pump (P) by pressing the green pushbutton at the front panel. After pump start-

up, close the pump by-pass valve (BV).






8. Switch ON the heater on the front panel.

9. Let the water to circulate throughout tanks T1 and T2 until the water temperature

reaches to about 500C.

Note:

TIC has an ON/OFF alarm with hysteresis of 0.50C.


Say the temperature set point is at 50.00C, the heater is switched ON until the

water temperature reaches 50.00C. TIC will then switch the heater OFF. The

water temperature will continue to rise and then drop to below 50.00C.

Once the water temperature drops below 49.50C, TIC will switch the heater ON

again to heat the water up to the set point temperature again.

This will continue throughout as long as the heater switch at the front panel

stays ON.

10. Switch the heater OFF.




Open the bottom globe valve of tank T1 to allow the water in tank T1 to flow

into tank T2 until the level at LG reads about 700mm. Close the bottom

globe valve.

Take 2 set of reading and record in the Table 3.

Continue measure the level from 600mm until 300 mm


(Tank T1 as CLOSED Tank, Heater ON)



2. Check that tank T1 is still operated as an OPEN tank.

Make sure that the top vent (V) and overflow manual valve are fully open.

Make sure that the manual discharge valves i.e. bottom gate valve is fully open

and globe valve is fully closed.

The pressurising air inlet manual isolation valve handle is 900 to the air supply

inlet tubing.

3. Open one turn of the pump by-pass valve (BV) first before starting the pump

(P).Start pump (P) by pressing the green pushbutton at the front panel. After pump

start-up, check that the pump by-pass valve (BV) is fully closed.






6. Switch ON the heater on the front panel. Let the water to circulate throughout tanks

T1 and T2 until the water temperature reaches to about 500C.

Note:

a. TIC has an ON/OFF alarm with hysteresis of 0.50C.


b. Say the temperature set point is at 50.00C, the heater is switched ON until

the water temperature reaches 50.00C. TIC will then switch the heater OFF.

The water temperature will continue to rise and then drop to below 50.00C.

c. Once the water temperature drops below 49.50C, TIC will switch the heater

ON again to heat the water up to the set point temperature again.

d. This will continue throughout as long as the heater switch at the front panel

stays ON.

7. Switch the heater OFF.


9. Open the bottom globe valve of tank T1 to allow the water in tank to flow out into

tank T2 until the level at LG reads to about 750mm. Close the bottom globe valve.

10. Then pressurise tank T1 as detailed below:

Fully CLOSE the vent (V), overflow, bottom gate valve and globe valves of

tank T1.

Pressurise the top space of tank T1 by opening the pressurising air inlet manual

isolation valve (with the valve handle in parallel to the air supply inlet tubing)

located next to the AS for air to flow into the top of tank T1.

Check that the pressure at pressure gauge is between 2.50 – 3.00 psig.

Note: Tank T1 is now a closed tank under pressure.





bottom globe valve.

Take 2 set of reading and record in table 4

Continue measure the level from 600mm until 300 mm.

1.6 Plant Shut-down Procedures

After all of the experiments have been completed, do the following:

1. Make sure that all the heaters and pump (P) are switched OFF.

2. Make sure that the air inlet manual isolation valve handle is in 900 positions at

the air supply inlet tubing. The top space of tank T1 is at atmospheric

pressure. Check the pressure gauge (PG) as well.

3. Fully open the overflow manual valve and the top vent (V) valve of tank T1.

4. Drain out all of the water in tank T1 by opening the manual discharge valve

i.e. the gate valve. After that, fully close both the gate valve and globe valve.

5. Drain out all of the water in tank T2 by opening its manual drain valve.

6. Switch OFF the main power supply.


2.0 RESULTS

2.1 TABLE 1: Level Measurement (Tank T1 as OPEN tank, Heater OFF)

RUN I SET 1 SET 2 AVERAGE

A Suggested Level (mm) 700 700 700

B Actual Level (LG) (mm)

C Actual Level (LI) (mm)

D Temperature (TG) (0C)

E Deviation = | B-C | (mm)

RUN II SET 1 SET 2 AVERAGE
























REMARKS:

B: Read from the sight glass with millimetre scale (LG).

C: Read from the level indicator (LI) on the front panel.

D: Read from the temperature gauge (TG) mounted on level tank T1.


2.2 TABLE 2: Level Measurement (T1 as CLOSED tank, Heater OFF)













RUN III SET 1 SET 2 AVERAGE






RUN IV SET 1 SET 2 AVERAGE






RUN V SET 1 SET 2 AVERAGE






REMARKS:





2.3 TABLE 3: Level Measurement (Tank T1 as OPEN tank, Heater ON)































REMARKS:





2.4 TABLE 4: Level Measurement (Tank T1 as CLOSED tank, Heater ON)































REMARKS:





3.0 QUESTIONS

1. Level is measured in many of the processes in the industry. List and explain the most

common reasons for measuring level.

2. Name the two methods of level measurement used in the experiment.

3. How the depth of a liquid does correspond to changes in liquid pressure? Can a

pressure transmitter be used to measure level?

4. The differential pressure transmitter is used to measure level in an open tank or closed

tank system. Discuss how this is done.

5. Discuss briefly the possible errors affecting the accuracy in pressure / level

measurement as observed in the experiment.

6. What are the main objectives of a wet lag calibration?

4.0 REFERENCE

1. Experiment Manual LMC 200. QDR Marketing Sdn Bhd


Documents

Exp 4-Process Instrument