Temperature Mesurment Table PDF

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Experiment InstructionsWL 202 Fundamentals ofTemperature Measurementiiiii All rights reserved, G.U.N. Gerätebau, Barsbüttel, Germany 03/ 1 Introduction Table of Contents 2 Safety 2 Intended use 2 Structure of safety instructions 2 Safety instructions 3 Unit description 3 Layout of the unit 3 Heat so...

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Experiment Instructions WL 202

Fundamentals of Temperature Measurement

All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 03/2018

WL 202

FUNDAMENTALS OF TEMPERATURE MEASUREMENT

Experiment Instructions

Last modification by: Dipl.-Ing. (FH) Peter Mittasch

This manual must be kept by the unit. Before operating the unit: - Read this manual. - All participants must be instructed on handling of the unit and, where appropriate, on the necessary safety precautions.

Version 0.7

Subject to technical alterations

i

WL 202

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

WL 202

FUNDAMENTALS OF TEMPERATURE MEASUREMENT

Table of Contents 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1 Intended use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Structure of safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

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2.3 Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3

Unit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.1 Layout of the unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2 Heat sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.3 Digital multimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.4 Contact Thermometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.5 Psychrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.6 Electrical temperature measurement. . . . . . . . . . . . . . . . . . . . . . . . . 11 3.6.1

Pt100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3.6.2

NTC thermistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.6.3

Thermocouple, type K. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.7 Placing in operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.7.1

Heat source and temperature sensor connection. . . . . . . . . 14

3.7.2

Use of shunt resistances . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.7.3

Use of adapter cable and multimeter . . . . . . . . . . . . . . . . . . 17

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

Temperature measurement procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.1 Temperature measurement using liquid thermometers . . . . . . . . . . . 19 4.2 Temperature measurement using bimetallic thermometers . . . . . . . 20 4.3 Temperature measurements using gas thermometers . . . . . . . . . . . 21 4.4 Temperature measurement using temperature measuring strips . . . 22 4.5 Temperature and resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.5.1

Temperature measurement using resistor thermometers. . . 23

4.5.2

Temperature measurement using thermistors . . . . . . . . . . . 26

4.6 Temperature measurement using thermocouples . . . . . . . . . . . . . . . 27 4.7 Measuring humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4.8 Calibration – adjustment – official calibration . . . . . . . . . . . . . . . . . . 33 5

Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 5.1 Testing the Pt100, NTC and thermocouple sensor . . . . . . . . . . . . . . 35 5.1.1

Experiment aim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

5.1.2

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

5.1.3

Performing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 36

5.1.4

Measurement and evaluation . . . . . . . . . . . . . . . . . . . . . . . . 37

5.2 Testing the gas pressure, bimetallic and liquid thermometers . . . . . 38 5.2.1

Experiment aim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.2.2

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.2.3

Performing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 38

5.2.4

Measurement and evaluation . . . . . . . . . . . . . . . . . . . . . . . . 39

5.3 Testing temperature displays with fixed resistances . . . . . . . . . . . . . 40

iv

5.3.1

Experiment aim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.3.2

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.3.3

Performing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 40

5.3.4

Measurement and evaluation . . . . . . . . . . . . . . . . . . . . . . . . 41

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

5.4 Calibration of the NTC temperature measuring instrument . . . . . . . . 45 5.4.1

Experiment aim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.4.2

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.4.3

Performing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 45

5.4.4

Measurement and evaluation . . . . . . . . . . . . . . . . . . . . . . . . 46

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5.5 Plotting a temperature characteristic curve for a Pt100 resistance thermometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

6

5.5.1

Experiment aim. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

5.5.2

Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

5.5.3

Performing the experiment . . . . . . . . . . . . . . . . . . . . . . . . . . 48

5.5.4

Measurement and evaluation . . . . . . . . . . . . . . . . . . . . . . . . 49

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 6.1 Work sheets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 6.2 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 6.3 Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 6.3.1

Pt100 measuring resistance in accordance with DIN IEC 751 59

6.3.2

Thermocouple type K in accordance with DIN IEC 584 . . . . 60

6.3.3

Psychrometer table for still air . . . . . . . . . . . . . . . . . . . . . . . 64

6.4 Thermistor NTC calculation example . . . . . . . . . . . . . . . . . . . . . . . . 66 6.5 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

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1

Introduction

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There are numerous ways of measuring temperature. These utilise various physical processes to acquire temperatures. The indication of the value measured can be direct. In this case the temperature acquisition medium is linked to a scale. In industry, temperatures are often measured by electronic means. The measured values are indicated on digital displays. In addition, the values measured are converted into standardised electrical signals so that the temperature information can be supplied to remote displays and otherequipment for further processing (controllers). Different types of thermometers and electronic sensors are contained in the WL 202 Fundamentals of Temperature Measurement unit. The values measured by the sensors can be read off on digital displays. At the same time, a standardised signal (0...10V) is output on laboratory sockets so that the change in the measured values over time can be recorded using a recorder. The unit includes several heat sources that also enable higher temperatures to be generated. In this way, it is ensured that the measuring range in which the individual temperature measuring devices are normally used can be reached.

1 Introduction

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

1 Introduction

FUNDAMENTALS OF TEMPERATURE MEASUREMENT

WL 202

2

Safety

2.1

Intended use The unit is to be used only for teaching purposes.

2.2

Structure of safety instructions

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The signal words DANGER, WARNING or CAUTION indicate the probability and potential severity of injury. An additional symbol indicates the nature of the hazard or a required action.

Signal word

DANGER

Indicates a situation which, if not avoided, will result in death or serious injury.

WARNING

Indicates a situation which, if not avoided, may result in death or serious injury.

CAUTION

Indicates a situation which, if not avoided, may result in minor or moderately serious injury.

NOTICE

2 Safety

Explanation

Indicates a situation which may result in damage to equipment, or provides instructions on operation of the equipment.

3

WL 202

FUNDAMENTALS OF TEMPERATURE MEASUREMENT

Symbol

Explanation Electrical voltage

Hazard (general)

Hot surfaces

Notice

2.3

Safety instructions

WARNING Reaching into the open control cabinet can result in electric shocks. • Disconnect from the mains supply before opening. • Work should only be performed by qualified electricians. • Protect the control cabinet against moisture.

4

2 Safety

WL 202

FUNDAMENTALS OF TEMPERATURE MEASUREMENT

All rights reserved, G.U.N.T. Gerätebau, Barsbüttel, Germany 03/2018

WARNING Risk of burns due to surface temperatures up to 400°C on the hot plate and immersion heater. • Do not touch the hot plate and immersion heater during operation. • At the end of the experiment, allow the heater to cool down before it is packed away.

NOTICE Surface temperatures up to 400°C on the hot plate and immersion heater. Components with a low melting point may condense. • Keep the hot plate and immersion heater away from heat-sensitive components during operation. • At the end of the experiment, allow the heater to cool down before it is packed away.

NOTICE Only use the measuring sensors and thermometers within the temperature ranges indicated (see Chapter 6.2, Page 54) . Incorrect use will damage the instruments and cause false readings in subsequent measurements.

2 Safety

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

NOTICE When reprogramming the digital displays, make sure that the signal applied corresponds to the set input range (e.g. resistance – resistance). Incorrect signals can destroy the displays.

6

2 Safety

FUNDAMENTALS OF TEMPERATURE MEASUREMENT

WL 202

3

Unit description

3.1

Layout of the unit

8

9

28°C

7

D SP

PAR

F1

F2

10

28.5°C

R ST

D SP

PAR

F1

F2

R ST

28°C D SP

PAR

F1

F2

R ST

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11 R

6

12 120 80

120 160

40

200 0

80

160

40

200 0

C

C

5

13

4 3

2 1

1

17

16

15

14

Master switch (left side)

10

Digital display for type K thermocouple

2

Storage case

11

Liquid thermometer

3

Socket (unregulated)

12

Bimetallic thermometer

4

Socket with power regulator

13

Gas pressure thermometer

5

14

Insulated flask

6

Switch of the Socket (3) Resistors 10  , 100  and 1000 

15

Psychrometer

7

Digital multimeter

16

Laboratory heater for water and sand

8

Digital display for Pt 100

17

Power control switch for (4)

9

Digital display for Thermistor (NTC)

Fig. 3.1

3 Unit description

WL 202 experimental unit

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

WL 202

The following parts are stored in the case:

1

3

4

5

7

6

1

Immersion heater

5

Type K thermocouple

2

Temperature measuring strip set

6

Adapter for thermocouple

3

Pt100 sensor

4

Adapter for Pt100

Fig. 3.2

3.2

2

7

Thermistor (NTC)

Other components of WL 202

Heat sources Two sockets are built into the experimental unit, these can be used to supply electrical power to both an immersion heater and a laboratory heater. One socket has a power regulator so that the power supplied to the immersion heater can be adjusted. The immersion heater is predominantly used to heat water in the insulated flask. There is a hole in the lid of the insulated flask through which the thermometer can be inserted.

8

3 Unit description

FUNDAMENTALS OF TEMPERATURE MEASUREMENT

WL 202

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NOTICE It must be ensured that there is always enough water in the flask so that it is not irreparably damaged by overheating

3

The laboratory heater has a built-in energy controller (1). This is used to adjust the power.

2

Position 1: 10% Position 1,5: 50% Position 3: 100%

1

Fig. 3.3

Laboratory heater

3.3

Digital multimeter

A vessel (3) can be placed on the hot plate (2), which can be filled either with water (temperatures up to 100 °C) or with sand or oil (temperatures up to 400 °C).

The digital multimeter can be used to measure the output voltages of the digital displays. The following relationship applies: Pt100 Temperature measuring range:0...100 °C Output signal: 0...10 V NTC Temperature measuring range:0...100 °C Output signal: 0...10 V Thermocouple Temperature measuring range:0...1000°C Output signal: 0...10 V

3 Unit description

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

WL 202

3.4

Contact Thermometers

120 80

160

40

200 0 C

Fig. 3.4

Bimetallic thermometer

All contact thermometers are held such that their sensing element is in the medium to be measured. The temperature can then be read off on a scale. Depending of the design of the thermometer, the period required until the temperature of the medium and that indicated on the scale match can be longer or shorter. When using temperature measuring strips that are bonded to a surface, the surface temperature should be estimated first to avoid wasting measuring strips unnecessarily; the change from light to dark is irreversible.

Indication adjustment gas pressure thermometer After removal of the screw positioned at the top of the case, a retaining screw at the movement becomes accessible, which can be regulated with a screwdriver. Only conduct indication adjustments if you can check the indication with a reference measurement.

Indication adjustment bimetallic thermometer There is an adjusting screw on the back side. With a no. 6 hexagon Allen key turn the dial carefully until the pointer reaches the reference value. Only conduct indication adjustments if you can check the indication with a reference measurement.

10

3 Unit description

FUNDAMENTALS OF TEMPERATURE MEASUREMENT

WL 202

3.5

Psychrometer Atmospheric humidity can be determined using a psychrometer. 2

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1

3 4 5

For this purpose two thermometers are fitted to a board. One thermometer (1) measures the temperature at atmospheric humidity. The second thermometer (2) measures the temperature at 100% humidity. For this purpose the bulb (3) on the thermometer is wrapped in a wet cloth (4). To avoid the need to continually moisten the cloth, the other end of the cloth is placed in a container (5) filled with water. The humidity is determined using the table in Chapter 6.3.3, Page 64

Fig. 3.5

Psychrometer

3.6

Electrical temperature measurement Three temperature sensors are fitted to the unit, these convert the temperature into electrical signals. These signals are indicated on digital displays.

3 Unit description

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FUNDAMENTALS OF TEMPERATURE MEASUREMENT

WL 202

3.6.1

Pt100

1

28°C DSP

PAR

F1

F2

RST

5

2 3 4

R

1

Digital display

2

Pt100 socket

3

Laboratory sockets (Pt100 simulation)

4

Sockets for resistors (10  , 100  , 1000  ) Laboratory sockets (output 0...10V)

5

Fig. 3.6

The digital display is programmed such that when a Pt100 sensor is connected to the input, the correct temperature is automatically displayed. The Pt100 sensor is connected in a thr...