Fluke 51 User manual

®
51 & 52 Series II
Thermometer
Users Manual
English
September 1999 Rev.1, 6/01
© 1999-2001 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.

Limited Warranty & Limitation of Liability
This Fluke product will be free from defects in material and workmanship for 3 years from the date of purchase. This war-
ranty does not cover fuses, disposable batteries or damage from accident, neglect, misuse or abnormal conditions of opera-
tion or handling. Resellers are not authorized to extend any other warranty on Fluke’s behalf. To obtain service during the
warranty period, send your defective tester to the nearest Fluke Authorized Service Center with a description of the problem.
THIS WARRANTY IS YOUR ONLY REMEDY. NO OTHER WARRANTIES, SUCH AS FITNESS FOR A PARTICULAR
PURPOSE, ARE EXPRESSED OR IMPLIED. FLUKE IS NOT LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR
CONSEQUENTIAL DAMAGES OR LOSSES, ARISING FROM ANY CAUSE OR THEORY. Since some states or countries
do not allow the exclusion or limitation of an implied warranty or of incidental or consequential damages, this limitation of
liability may not apply to you.
Fluke Corporation
P.O. Box 9090
Everett WA
98206-9090
Fluke Europe B.V.
P.O. Box 1186
5602 B.D. Eindhoven
The Netherlands
To register your product, visit www.fluke-warranty.com
10/96

i
Table of Contents
Title Page
Introduction....................................................................................................................1
Contacting Fluke....................................................................................................... 1
Getting Started............................................................................................................... 4
Components.............................................................................................................. 5
Display Elements...................................................................................................... 6
Buttons...................................................................................................................... 7
Using the Thermometer................................................................................................. 9
Changing Setup Options................................................................................................ 9
Entering or Exiting Setup.......................................................................................... 9
Setup Options........................................................................................................... 9
Changing a Setup Option.......................................................................................... 10
Measuring Temperatures............................................................................................... 11
Connecting a Thermocouple..................................................................................... 11
Displaying Temperatures.......................................................................................... 11
Holding the Displayed Readings............................................................................... 12
Viewing the MIN, MAX, and AVG Readings.............................................................. 12
Using the Offset to Adjust for Probe Errors.................................................................... 12

51 & 52 Series II
Users Manual
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Maintenance................................................................................................................... 13
Replacing the Batteries ............................................................................................. 13
Cleaning the Case and Holster.................................................................................. 13
Calibration ................................................................................................................. 13
Specifications................................................................................................................. 13
Environmental............................................................................................................ 13
General...................................................................................................................... 14
80 PK-1 Thermocouple (supplied with thermometer) ................................................ 14
Electrical.................................................................................................................... 14
Replacement Parts and Accessories.............................................................................. 15

1
51 & 52 Series II
Introduction
The Fluke Model 51 and Model 52 Thermometers (“the
thermometer”) are microprocessor-based, digital
thermometers designed to use external J-, K-, T-, and E-
type thermocouples (temperature probes) as temperature
sensors.
Use the thermometer only as specified in this manual.
Otherwise, the protection provided by the meter may be
impaired.
Refer to safety information in Table 1 and meter symbols
in Table 2.
Contacting Fluke
To order accessories, receive assistance, or locate the
nearest Fluke distributor or Service Center, call:
1-888-99-FLUKE (1-888-993-5853) in USA
1-800-36-FLUKE (1-800-363-5853) in Canada
[phone] in Europe
[phone] in Japan
[phone] in Singapore
[phone] from other countries
Address correspondence to:
Fluke Corporation Fluke Europe B.V.
P.O. Box 9090 P.O. Box 1186
Everett, WA 98206-9090 5602 BD Eindhoven
USA The Netherlands
Visit us on the World Wide Web at: www.fluke.com
To register your product, visit www.fluke-warranty.com

51 & 52 Series II
Users Manual
2
Table 1. Safety Information
WWarning
A Warning identifies conditions and actions that pose hazards to the user. To avoid electrical shock or
personal injury, follow these guidelines:
•Before using the thermometer inspect the case. Do not use the thermometer if it appears damaged. Look
for cracks or missing plastic. Pay particular attention to the insulation around the connectors.
•Disconnect the thermocouple(s) from the thermometer before opening the case.
•Replace the batteries as soon as the battery indicator (B) appears. The possibility of false readings can
lead to personal injury.
•Do not use the thermometer if it operates abnormally. Protection may be impaired. When in doubt, have the
thermometer serviced.
•Do not operate the thermometer around explosive gas, vapor, or dust.
•Do not apply more than the rated voltage, as marked on the thermometer, between the thermocouple(s), or
between any thermocouple and earth ground.

51 & 52 Series II
Introduction
3
Table 1. Safety Information (cont.)
WWarning (cont.)
• Model 52: Measurement errors may occur if voltages on the measurement surfaces result in potentials
greater than 1 V between the two thermocouples. When potential differences are anticipated between the
thermocouples, use electrically insulated thermocouples.
•When servicing the thermometer, use only specified replacement parts.
•Do not use the thermometer with any part of the case or cover removed.
Caution
A Caution identifies conditions and actions that may damage the meter or the equipment under test.
•Use the proper thermocouples, function, and range for your thermometer.
•Do not attempt to recharge the batteries.
•To prevent explosion, do not throw batteries into a fire.
•Follow local laws or regulations when disposing of batteries.
•Match the +and −polarities of the battery with the battery case.

51 & 52 Series II
Users Manual
4
Table 2. International Symbols
WRefer to the manual for information about this
feature. PComplies with European Union directives.
MBattery. Complies with relevant Canadian Standards
Association directives.
Getting Started
Everything in this Users Manual applies both to Models
51 and 52 unless otherwise indicated.
To become familiar with the thermometer, study the
following:
•Figure 1 and Table 3 describe the components.
•Figure 2 and Table 4 describe the display.
•Table 5 describes the functions of the buttons.
Then read the following sections.

51 & 52 Series II
Getting Started
5
Components
xx
3
4
512
6
7
aas01f.eps
Figure 1. Components
Table 3. Components
AThermocouple T1 input
B Model 52: Thermocouple T2 input
CHolster
DDisplay
EButtons
FBattery door
GBatteries

51 & 52 Series II
Users Manual
6
Display Elements
xx
2345
6
7
8
9
10
1
aas02f.eps
Figure 2. Display Elements
Table 4. Display Elements
AThe thermocouple measurement includes an
offset. See "Changing Setup Options."
BThe displayed readings do not change.
CA shift function is in progress.
DSetup is in progress.
ELow battery. Replace the batteries.
FPrimary Display.
Model 51 : T1 reading.
Model 52: T1, T2, or T1-T2 reading.
GThe temperature unit.
HSecondary Display: MAX, MIN, AVG, or offset.
Model 52: T1or T2 reading.
IThe thermocouple type.
JTime Display: The elapsed time.

51 & 52 Series II
Getting Started
7
Buttons
Table 5. Buttons
APress Ato turn the thermometer on or off.
G
(Shift
function)
Press G, M(CANCEL) to stop displaying the minimum, maximum, and average readings in the
secondary display.
QPress Qto turn the backlight on and off. The backlight turns off after 2 minutes without any button
presses. If the battery is low, the backlight is disabled.
MPress Mto step through the maximum, minimum, and average readings. When viewing logged
readings, shows the maximum, minimum, and average of the logged readings.
Press G, M(CANCEL) to turn off this display.
CPress Cto switch between Celsius (oC), Fahrenheit (oF), and Kelvin (K).
hPress hto freeze or unfreeze the displayed readings.
Press hwhen turning on the thermometer to test the display. All display elements appear.
T
Model 52: Press Tto toggle showing the T1, T2, and T1-T2 (differential temperature measurement) in the
primary or secondary display.

51 & 52 Series II
Users Manual
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Table 5. Buttons (cont.)
DPress Dto start or exit Setup. (See "Changing Setup Options.")
KPress Kto scroll to the Setup option you want to change.
Press Kto increase the displayed setting.
NPress Nto scroll to the Setup option you want to change.
Press Nto decrease the displayed setting.
EPress Eto enter a Setup option.
Press Eagain to store the displayed setting in memory.

51 & 52 Series II
Using the Thermometer
9
Using the Thermometer
1. Plug the thermocouple(s) into the input connector(s).
2. Press
Ato turn on the thermometer.
After 1 second the thermometer displays the first reading.
If no thermocouple is plugged into the selected input or the
thermocouple is "open," the display shows "- - - -"
Changing Setup Options
Use Setup to change the thermocouple type, offset, sleep
mode, and line frequency settings.
The thermometer stores the settings in its memory. Setup
settings reset only when the batteries are removed for
more than 2 minutes.
Entering or Exiting Setup
When the thermometer is in Setup mode, the display
shows s.
•Press
Dto start or exit Setup.
Setup Options
Option Menu Item Settings
Thermocouple
Type TYPE J, K, T, or E
Offset OT1 or T2 (Model 52)
Sleep Mode SLP on (sleep mode on)
or 0FF (sleep mode
off)
Line Frequency Li ne 50 H (50 Hz)
or 60 H (60 Hz)

51 & 52 Series II
Users Manual
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Changing a Setup Option
1. Press K or Nto scroll to the setup option you
want to change.
2. Press
Eto indicate that you want to change this
setting.
3. Press
K or Nuntil the setting you want to use
appears on the display.
4. Press
Eto store the new setting in memory.
Notes
Setup is disabled in MIN MAX mode.
Offset:
The primary display shows the temperature plus
the offset and the secondary display shows the
offset. Remember to reset the offset to 0.0 when
it is no longer needed. The offset automatically
resets to 0.0 when you change the thermocouple
type. Model 52: You can store individual offsets
for T1 and T2.
Sleep mode:
The thermometer enters sleep mode if no button
press occurs for 20 minutes. Pressing any button
wakes the thermometer and returns it to its
previous state. Sleep mode becomes enabled
each time you turn on the thermometer and is
automatically disabled in MIN MAX mode.
Line frequency:
For optimum rejection of line noise, the
thermometer must be set for the local line
frequency.

51 & 52 Series II
Measuring Temperatures
11
Measuring Temperatures
Connecting a Thermocouple
To change the thermocouple type, see “Changing Setup
Options.” The North American ANSI Color Code is:
Type JKETN
Color Black Yellow Purple Blue Orange
1. Plug a thermocouple into the input connector(s).
(Make sure that the polarity is correct.)
2. Set the thermometer for the correct thermocouple
type.
Displaying Temperatures
1. Press Cto select the correct temperature scale.
2. Hold or attach the thermocouple(s) to the
measurement location.
The temperature reading appears in the primary
display.
3.
Model 52: Press Tto toggle between showing the
T1, T2, and T1-T2 readings in the primary or
secondary display.
Notes
The display shows "- - - -" when a thermocouple
is not connected.
The display shows
0L (overload) when the
temperature being measured is outside the
thermocouple’s valid range.
Model 52: If only thermocouple T2 is connected,
the T2 reading appears in the primary display.

51 & 52 Series II
Users Manual
12
Holding the Displayed Readings
1. Press hto freeze the readings on the display.
The display shows H.
2.
Model 52: Press Tto toggle showing the T1, T2, or
T1-T2 readings in the primary or secondary display.
3. Press
hagain to turn off the HOLD function.
Viewing the MIN, MAX, and AVG Readings
1. Press Mto step through the maximum (MAX),
minimum (MIN), or the average (AVG) readings.
The elapsed time since entering MIN MAX mode, or
the time at which the minimum or maximum occurred,
appears on the display.
2. Press
G, M(CANCEL) to exit MIN MAX mode.
Using the Offset to Adjust for Probe
Errors
Use the offset option in Setup to adjust the thermometer’s
readings to compensate for the errors of a specific
thermocouple.
The allowable adjustment range is ±5.0 oC or K, and
±9.0 oF.
1. Plug the thermocouple into the input connector.
2. Place the thermocouple in a known, stable
temperature environment (such as an ice bath or a
dry well calibrator).
3. Allow the readings to stabilize.
4. In Setup change the offset until the primary display
reading matches the calibration temperature. (See
"Changing Setup Options.")

51 & 52 Series II
Maintenance
13
Maintenance
Replacing the Batteries
Refer to the safety information in Table 1 before replacing
the batteries.
1. Turn off the thermometer if necessary.
2. Loosen the screw and remove the battery door.
3. Replace the three AA batteries.
4. Replace the battery door and tighten the screw.
Cleaning the Case and Holster
Use soap and water or a mild commercial cleaner.
Wipe with a damp sponge or soft rag.
Calibration
To ensure that the thermometer performs to its accuracy
specifications, Fluke recommends that you calibrate the
thermometer annually, starting one year after purchase.
To calibrate the thermometer, contact Fluke for the
Service Center nearest you or follow the calibration
procedure in the service manual listed in "Replacement
Parts and Accessories."
Specifications
Environmental
Operating
Temperature −10 oC to 50 oC (14oF to 122oF)
Storage
Temperature −40oC to +60 oC (−40 oF to +140oF)
Humidity Non condensing <10oC (<50oF)
95% RH: 10oC to 30oC (50oF to 86oF)
75% RH: 30oC to 40oC (86oF to 104oF)
45% RH: 40oC to 50oC (104oF to 122oF)

51 & 52 Series II
Users Manual
14
General
Weight 280 g (10 oz)
Dimensions
(without
holster)
2.8 cm ×7.8 cm ×16.2 cm
(1.1 in ×3 in ×6.4 in)
Battery 3 AA batteries
Certification P, )s
Safety CSA C22.2 No. 1010.1 1992
EN 61010 Amendments 1, 2
CAT I OVERVOLTAGE (Installation)
CATEGORY I, Pollution Degree 2
per IEC1010-1*
* Refers to the level of Impulse Withstand Voltage protection
provided. Equipment of OVERVOLTAGE CATEGORY I is
equipment for connection to circuits in which measures are
taken to limit the transient over voltages to an appropriate low
level. Example include protect electronic circuits.
80 PK-1 Thermocouple (supplied with
thermometer)
Type Type K, Chromel Alumel, bead style
Temperature
Range −40 oC to +260 oC (−40 oF to +500 oF)
Accuracy ±1.1 oC (±2.0 oF)
Electrical
Measurement
Range J-type: −210 oC to +1200 oC (−346 oF to +2192 oF)
K-type: −200 oC to +1372 oC
(−328 oF to +2501 oF)
T-type: −250 oC to +400 oC
(−418 oF to +752 oF)
E-type: −150 oC to +1000 oC
(−238 oF to +1832 oF)
Display
Resolution 0.1 oC / oF / K <1000o
1.0 oC / oF / K ≥1000o

51 & 52 Series II
Replacement Parts and Accessories
15
Electrical (cont.)
Measurement
Accuracy, T1,
T2, or T1-T2
(Model 52)
J-, K-, T-, and E-type: ±[0.05 %of
reading +0.3 oC (0.5 oF)]
[below −100 oC (−148 oF): add 0.15 %
of reading for J-, K-, E-, and N-type;
and 0.45 % of reading for T-type]
Temperature
Coefficient 0.01 %of reading +0.03 oC per oC (0.05 oF per oF) outside the
specified +18 oC to 28 oC (+64oF
to +82 oF) range
[below −100 oC (−148 oF): add
0.04 % of reading for J-, K-, E-, and
N-type; and 0.08 % of reading for
T-type]
Electromagnetic
Compatibility Susceptibility: ±2oC (±3.6oF) for 80
MHz to 200 MHz in 1.5 V/m field, for
200 MHz to 1000 MHz in 3 V/m field.
Emmisions: Commercial Limits per
EN50081-1
Maximum
Differential
Common Mode
Voltage
1 V (Maximum voltage difference
between T1 and T2)
Temperature
Scale ITS-90
Applicable
Standards NIST-175
Accuracy is specified for ambient temperatures
between 18 oC (64 oF) and 28 oC (82 oF) for a period of
1 year. The above specifications do not include
thermocouple error.
Replacement Parts and Accessories
Accessory Part Number
Holster and Flex StandAssembly 1272438
AA NEDA 15A IEC LR6 batteries 376756
80PK-1 K-Type Bead Thermocouple 773135
CD-ROM 1276106
Service Manual 1276123

51 & 52 Series II
Users Manual
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