pdc lab report

8/10/2019 PDC Lab Report

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LAB REPORT PROCESS AND

DYNAMIC CONTROLSUBMITTED TO: SIR HASEEB JATOI

SUBMITTED BY:

ARSLAN ALI (2011-CH-63)

UNIVERSITY OF ENGINEERING & TECHNOLOGY

LAHORE


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LAB#011TH

SEPTEMBER,2014LAB LAYOUT


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LAB#028TH

SEPTEMBER,2014DEADWEIGHTCALIBRATOR

OBJECTIVE

Calibration of Pressure Gauge using Dead Weight Calibrator

EQUIPMENT

1. The Dead Weight Calibrator

2. Standard Weights

3. Precision Gauge (if possible)

PROCEDURE

1. We closed the Needle Valves #2, #3, #4 while keeping the valve #1 open, so that the oil

can be added to the system

2. We checked the level of hydraulic oil in the Oil Cup; it was fill up to the mark. (in case

oil is less, add more oil to fill the cup unless the hydraulics may not develop).


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3. Rotate the piston handle outwards completely to suck the oil in it.

4. We closed Needle Valve #1 now and opened Valve #2 (Pan for Weights) and Valve #3

(Pressure Gauge) after mounting the gauge to be tested on the nipple provided above

Needle Valve #3. (In case a precision gauge is also mounted, then open the valve #4 as

well, we didnt had any such gauge) Hence Oil flows to these points now and hydraulics

developed.

5. After this, we in ascending order put the standard weights on the Pan

6. Turn the handle of the cylinder piston to transmit the pressure toward the weight and

pressure gauge/s

7. When the fluid pressure is equal to the pan, it is lifted as well as the gauge indicates the

corresponding pressure. Note that the weight should be lifted to red line only. Beyond

white line it would be in effective.

8. We noted the reading and increased the weights in ascending order and then noted the

readings in descending order as well.

PRECAUTIONS

1. The relevant valves should be promptly closed and opened as mentioned in the

procedure; otherwise the hydraulic oil might spill outside or on the face of the users.

2. The standard weights should be placed, with care.

3. The hand wheel should be turned back before removing any heavy weights.

Weight Pressure (Kg/cm ) Inverse0 0.7 0.5

1 1.0 1.0

2 1.1 1.8

3 2.0 2.2

4 3.5 4

5 4.2 4.2

6 5.0 5.8

11 10.0 10.3

16 16.0 16

21 22.0 22

26 26.0 26.3

36 38.0 36.2

46 46 46

56 55.5 56

62 62.0 62


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0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

Weight v/s Rev.Pressure

`

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

Weight v/s Pressur


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LAB#0315TH

SEPTEMBER,2014THERMOCOUPLE

OBJECTIVE

To determine the time constant of a typical Iron-Constantan Thermocouple

EQUIPMENT

1. Thermocouple (JType: IronConstantan)

2. Heater

3. Digital Voltmeter

4.

Stopwatch5. Hookup Wires

PROCEDURE

Note the readings on the digital voltmeter. Switch on heater. As thermocouple receives heat,

digital voltmeter reading changes, record the reading every minute. After some time the

measured voltage shall settle on a particular time constant from the plot.

Draw graph of EMF V/S Time. Establish the time constant from the plot.

Establish the temperature at all measured EMF using the thermocouple table for

appropriate metals.


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OBSERVATIONS

EMFVS TIME

Graph:

TIME CONSTANT CALCULATIONS

Max Reading on digital voltmeter = 9.4

63.2% of Max = 5.9408 mV

Time Constant = 12.85 min

0.10.3

0.6

1

1.5

2.1

2.7

3.3

3.9

4.5

5.1

5.6

6.2

6.6

7

7.47.7

88.3

8.58.7

8.9 99.1

9.3 9.4 9.4 9.4

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0 2 2 2 4 2 6 2 8 3 0

EMF

TIME

EMF(MV) VS TIME (MIN)


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TEMP VS TIME

Graph:

TIME CONSTANT CALCULATIONS

Max Reading of Temperature = 175.14oC

63.2% of Max = 110.6885oC

Time Constant = 12.2 min

QUESTIONS/ANSWERS FOR BETTER UNDERSTANDING

I. What are different types of thermocouple and which type of thermocouple used here?

Thermocouples are identified by a single letter type and grouped according to their

temperature range

0

15

30

45

60

75

90

105

120

135

150

165

180

195

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Temp(DegC)

Time (min)

Temp( Deg C) Vs Time (min)


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1. Base Metals up to 1000 C Type J, Type E, Type T, Type K

2. Noble Metals up to 2000 C Type R, Type S, Type B

3. Refractory Metals up to 2600 C Type C, Type D, Type G

J-Type thermocouple was used in this experiment.

II. What do you know about SeeBeck Effect?

In 1821, Thomas Seebeck discovered if metals of two different materials were joined at both

ends and one end was at a different temperature than the other, a current was created. This

phenomenon is known as the Seebeck effect and is the basis for all thermocouples.

III. Why Thermocouples are preferred?

Thermocouples can be used to temperatures as high as 3100F, generally cost less than

RTDs and they can be made smaller in size (down to approximately .020 dia) to allow for

faster response to temperature. Thermocouples are also more durable than RTDs and can

therefore be used in high vibration and shock applications. Thermocouples are generally less

expensive than RTDs.

IV. Why results are not reliable?

Time of Response of thermocouple is very slow.


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V. Show Thermocouple measuring circuit?

VI. Can Thermocouple measure gas, liquid and solid temperature?

Yes, it can measure gas, liquid and solid surface temperature.

VII. Why is thermocouple inclined above the heater?

There is no such restriction of inclination angle, but it is done only as a precaution. Has the

Thermocouple been placed straightly above the heater, it would have heated up the wires

connected to its other end, which we dont want.

VIII. Which characteristics of thermocouple can be determined?

1. Response Time:

It is defined as the time required to reach 63.2% of an instantaneous temperature change.

2. Speed of Response:

The speed of response of a sensor mainly depends on his mass and thermocouples can be

very thin so fast response

3. Sensitivity:

Sensitivity of thermocouple refers to how much sensitive thermocouple is to any

change.

IX. What is Hot Junction and Cold Junction?

A thermocouple is a type of temperature sensor, which is made by joining two dissimilar

metals at one end. The joined end is referred to as the HOT JUNCTION. The other end of

these dissimilar metals is referred to as the COLD END or COLD JUNCTION.


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X. What is Cold Junction Compensation?

Simulate the potential effects that would result for a thermocouple wire pair between the

terminals, at their measured temperature, and another junction at a reference temperature of 0

degrees. Measure the potential across the thermocouple wire pair in series with the simulated

potential. Apply the linearizing curve to the sum, thus obtaining an estimated absolute

temperature directly. This is known as cold junction compensation. Usually, the simulation isdone electronically with specialized integrated circuit devices.

Electronic cold junction compensation

XI. Write on Thermocouple Installation?

Vertical installation is preferred in very high temperatures to avoid protection tube or

element sagging. Install thermocouples away from AC power lines to prevent electrical

noise. Do not run thermocouple wires in the same conduit with electrical wires.

Do not run a single thermocouple to two different instruments. This will result in instrument

imbalance.

A dual thermocouple should be used instead.

Electrical: Connect the positive thermocouple extension wire to the positive thermocouple

wire and the negative extension wire to the negative thermocouple wire.

TYPE J - The positive element is magnetic. It has a lower resistance in ohms per foot than

the negative element in the same wire gauge.


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TYPE K - The negative element is slightly magnetic. It has a lower resistance in ohms per

foot than the positive element in the same wire gauge.

TYPE E - The negative element has a lower resistance in ohms per foot than the positive

element for the same wire gauge.

TYPE T -The positive element is copper in appearance. It has a lower resistance per foot in

ohms than the negative element of the same wire gauge.

TYPE R or S -The negative element is softer. The positive element has a lower resistance in

ohms per foot than the negative element of the same wire gauge.

TYPE N -The positive element has a higher resistance in ohms per foot than the negative

element of the same wire gauge.

OPERATION:

The temperature of the connection head should be kept at ambient temperature if possible toavoid errors due to temperature gradient. The maximum recommended temperature at the

terminal block is 400F.

XII. Explain Measuring sensor mechanism of thermocouple?

One particular advantage of thermocouples is that the sensing elements themselves are very

small, allowing thermocouples to be inserted into very small spaces and to respond to rapidly

changing temperatures. The electrical nature of the process means that the circuitry for

reading the thermocouple output can be remote from the sensor itself. Note thatthermocouple effects will be encountered wherever one metallic conductor meets another, so

that temperature differences along circuit boards can also give rise to voltages which are

comparable with the output from thermocouples. The resistance to the flow of electricity inmetallic materials varies with temperature. This can be used to good effect in platinum

resistance detectors. Platinum is particularly stable both electrically and mechanically and is

also stable with respect to time, producing a relatively linear change in resistance versustemperature.

Because the output resistance change to temperature is relatively small, it follows that lead

lengths and resistances are therefore important features. In general when lead lengths are

short, or can be considered as an acceptable additive content, two wire configuration issufficient.

Three wire is the most commonly used and unless otherwise specified is supplied as

standard, the third wire is the compensator for lead length and providing that all three wirehave equal resistance, compensates for any ZERO or SPAN errors. (Not true for all bridges).

Four wire provides for high precision and is recommended for use with Zener Barriers.

XIII. What are the precautions while using thermocouple?

If operating at high temperatures, check the specifications of the probe insulation.


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It takes up to 5 s for the outputs to turn ON after the power supply is turned ON. Take this

time into consideration.

Connection: Many measurement errors are caused by unintentional junctions. Remember that

any junction of two different metals will cause a junction. If you need to increase the length

of the leads from your thermocouple, you must use the correct type of thermocouple

extension wire.

To minimize thermal loading and improve response times, thermocouples are often made of

thin wire. It is always a good precaution to measure the resistance of your thermocouple

before use.

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