MARATHON MM
SERIES
High-Performance Infrared Thermometer
Operating Instructions
Rev. D7 Jul 2017
58201
Contacts
Fluke Process Instruments
Americas
Santa Cruz, CA USA
Tel: +1 800 227 8074 (USA and Canada, only)
+1 831 458 3900
solutions@flukeprocessinstruments.com
EMEA
Berlin, Germany
Tel: +49 30 478 0080
info@flukeprocessinstruments.de
China
Beijing, China
Tel: +86 10 6438 4691
info@flukeprocessinstruments.cn
Worldwide Service
Fluke Process Instruments offers services,
including repair and calibration. For more
information, contact your local office.
www.raytek.com
© Fluke Process Instruments
Specifications subject to change without notice.
WARRANTY
The manufacturer warrants this instrument to be free from defects in material and workmanship under normal use
and service for the period of two years from date of purchase. This warranty extends only to the original purchaser.
This warranty shall not apply to fuses, batteries, or any product which has been subject to misuse, neglect, accident,
or abnormal conditions of operation.
In the event of failure of a product covered by this warranty, the manufacturer will repair the instrument when it
is returned by the purchaser, freight prepaid, to an authorized Service Facility within the applicable warranty
period, provided manufacturer’s examination discloses to its satisfaction that the product was defective. The
manufacturer may, at its option, replace the product in lieu of repair. With regard to any covered product returned
within the applicable warranty period, repairs or replacement will be made without charge and with return freight
paid by the manufacturer, unless the failure was caused by misuse, neglect, accident, or abnormal conditions of
operation or storage, in which case repairs will be billed at a reasonable cost. In such a case, an estimate will be
submitted before work is started, if requested.
THE FOREGOING WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS, OR
ADEQUACY FOR ANY PARTICULAR PURPOSE OR USE. THE MANUFACTURER SHALL NOT BE LIABLE
FOR ANY SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES, WHETHER IN CONTRACT, TORT,
OR OTHERWISE.
SOFTWARE WARRANTY
The manufacturer does not warrant that the software described herein will function properly in every hardware
and software environment. This software may not work in combination with modified or emulated versions of
Windows operating environments, memory-resident software, or on computers with inadequate memory. The
manufacturer warrants that the program disk is free from defects in material and workmanship, assuming normal
use, for a period of one year. Except for this warranty, the manufacturer makes no warranty or representation,
either expressed or implied, with respect to this software or documentation, including its quality, performance,
merchantability, or fitness for a particular purpose. As a result, this software and documentation are licensed “as
is,” and the licensee (i.e., the User) assumes the entire risk as to its quality and performance. The liability of the
manufacturer under this warranty shall be limited to the amount paid by the User. In no event shall the
manufacturer be liable for any costs including but not limited to those incurred as a result of lost profits or revenue,
loss of use of the computer software, loss of data, the cost of substitute software, claims by third parties, or for other
similar costs. The manufacturer’s software and documentation are copyrighted with all rights reserved. It is illegal
to make copies for another person.
Specifications subject to change without notice.
COMPLIANCE STATEMENT
The device complies with the requirements of the European Directives:
EC – Directive 2014/30/EU – EMC
EC – Directive 2011/65/EU – RoHS II
EN 61326-1: 2013 Electrical measurement, control and laboratory devices -
Electromagnetic susceptibility (EMC)
EN 50581: 2012 Technical documentation for the evaluation of electrical products with respect
to restriction of hazardous substances (RoHS)
Electromagnetic Compatibility Applies to use in Korea only. Class A
Equipment (Industrial Broadcasting & Communication Equipment)
This product meets requirements for industrial (Class A) electromagnetic wave equipment and
the seller or user should take notice of it. This equipment is intended for use in business
environments and is not to be used in homes.
Content
COMPLIANCE STATEMENT .......................................................................................................................... 5
CONTENT ............................................................................................................................................................ 6
1 SAFETY INSTRUCTIONS ........................................................................................................................... 10
2 PRODUCT DESCRIPTION .......................................................................................................................... 13
3 TECHNICAL DATA ...................................................................................................................................... 14
3.1 MEASUREMENT SPECIFICATIONS ............................................................................................................... 14
3.2 OPTICAL SPECIFICATIONS .......................................................................................................................... 16
3.2.1 Variable Focus ..................................................................................................................................... 16
3.2.2 Fixed Focus ......................................................................................................................................... 17
3.3 ELECTRICAL SPECIFICATIONS .................................................................................................................... 22
3.4 ENVIRONMENTAL SPECIFICATIONS ........................................................................................................... 22
3.5 DIMENSIONS ............................................................................................................................................... 23
3.6 SCOPE OF DELIVERY ................................................................................................................................... 23
4 BASICS ............................................................................................................................................................. 24
4.1 MEASUREMENT OF INFRARED TEMPERATURE .......................................................................................... 24
4.2 EMISSIVITY OF TARGET OBJECT.................................................................................................................. 24
5 ENVIRONMENT............................................................................................................................................ 25
5.1 AMBIENT TEMPERATURE ........................................................................................................................... 25
5.2 ATMOSPHERIC QUALITY ............................................................................................................................ 25
5.3 ELECTRICAL INTERFERENCE ...................................................................................................................... 25
6 INSTALLATION ............................................................................................................................................ 26
6.1 MECHANICAL INSTALLATION ................................................................................................................... 26
6.1.1 Distance to Object .............................................................................................................................. 26
6.1.2 Variable Focus ..................................................................................................................................... 26
6.1.3 Viewing Angles................................................................................................................................... 27
6.2 ELECTRICAL INSTALLATION ...................................................................................................................... 28
6.3 COMPUTER INTERFACING .......................................................................................................................... 30
6.4 MULTIPLE SENSORS IN A NETWORK .......................................................................................................... 32
6.4.1 Wiring ................................................................................................................................................ 32
6.4.2 Addressing .......................................................................................................................................... 33
6.4.3 Configuration Procedure .................................................................................................................... 33
7 OPERATION ................................................................................................................................................... 34
7.1 CONTROL PANEL ....................................................................................................................................... 34
7.2 OPERATION MODES ................................................................................................................................... 34
7.3 SIGNAL PROCESSING .................................................................................................................................. 37
7.3.1 Averaging ........................................................................................................................................... 37
7.3.2 Peak Hold ............................................................................................................................................ 38
7.3.2.1 Reset ............................................................................................................................................. 38
7.3.2.2 Signal Slope ................................................................................................................................. 39
7.3.3 Advanced Peak Hold ........................................................................................................................... 40
7.3.4 Valley Hold ......................................................................................................................................... 41
7.3.5 Advanced Valley Hold ........................................................................................................................ 41
7.4 INPUTS AND OUTPUTS ................................................................................................................................ 42
7.4.1 Milliamp Output ................................................................................................................................. 42
7.4.2 Relay Output....................................................................................................................................... 42
7.4.2.1 Thresholds .................................................................................................................................... 42
7.4.2.2 Deadband ..................................................................................................................................... 43
7.4.3 External Input ..................................................................................................................................... 44
7.4.3.1 Trigger .......................................................................................................................................... 44
7.4.3.2 Ambient Background Temperature Compensation ............................................................... 45
7.4.3.3 Emissivity Setting ........................................................................................................................ 47
7.5 FACTORY DEFAULTS ................................................................................................................................... 48
8 OPTIONS ......................................................................................................................................................... 49
8.1 LASER SIGHTING ......................................................................................................................................... 49
8.2 VIDEO SIGHTING ......................................................................................................................................... 50
8.3 AIR/WATER COOLED HOUSING ................................................................................................................. 53
8.3.1 Avoidance of Condensation ................................................................................................................. 54
9 ACCESSORIES ................................................................................................................................................ 55
9.1 OVERVIEW ................................................................................................................................................... 55
9.2 FIXED MOUNTING BRACKET ...................................................................................................................... 57
9.3 ADJUSTABLE MOUNTING BRACKET ........................................................................................................... 57
9.4 AIR PURGE COLLAR .................................................................................................................................... 58
9.5 SIGHT TUBE ................................................................................................................................................. 58
9.6 PIPE THREAD ADAPTER .............................................................................................................................. 59
9.7 RIGHT ANGLE MIRROR ............................................................................................................................... 60
9.8 INDUSTRIAL POWER SUPPLY ...................................................................................................................... 61
9.9 TERMINAL BOX ........................................................................................................................................... 62
9.10 LOW TEMP CABLE ..................................................................................................................................... 63
9.11 HIGH TEMP CABLE ................................................................................................................................... 64
9.12 PROTECTIVE WINDOW .............................................................................................................................. 65
9.13 THERMOJACKET ........................................................................................................................................ 66
9.14 {RESERVED}................................................................................................................................................ 66
9.15 {RESERVED}................................................................................................................................................ 66
10 PROGRAMMING GUIDE .......................................................................................................................... 67
10.1 SERIAL INTERFACE VERSUS CONTROL PANEL ......................................................................................... 67
10.2 STORING OF PARAMETERS ........................................................................................................................ 67
10.3 COMMAND STRUCTURE ............................................................................................................................ 67
10.3.1 Requesting a parameter (Poll Mode) ................................................................................................. 67
10.3.2 Setting a parameter (Poll Mode) ....................................................................................................... 67
10.3.3 Sensor response ................................................................................................................................. 68
10.3.4 Sensor notification............................................................................................................................. 68
10.3.5 Error Messages .................................................................................................................................. 68
10.4 TRANSFER MODES .................................................................................................................................... 68
10.5 CHECKSUM ................................................................................................................................................ 69
10.6 BURST MODE ............................................................................................................................................. 70
10.6.1 Speed ................................................................................................................................................. 70
10.6.2 Minimum Baud Rate......................................................................................................................... 71
10.7 SENSOR INFORMATION ............................................................................................................................. 71
10.8 SENSOR SETUP ........................................................................................................................................... 72
10.8.1 General Settings ............................................................................................................................... 72
10.8.2 Sample Time ..................................................................................................................................... 72
10.8.3 Temperature Pre-Processing ............................................................................................................. 72
10.8.4 Temperature Range........................................................................................................................... 74
10.8.5 Emissivity Setting ............................................................................................................................ 74
10.8.6 Ambient Background Temperature Compensation ........................................................................... 74
10.8.7 Temperature Hold Functions ............................................................................................................ 74
10.9 SENSOR CONTROL .................................................................................................................................... 75
10.9.1 Current Output ................................................................................................................................ 75
10.9.2 Relay Output .................................................................................................................................... 75
10.9.3 External Input .................................................................................................................................. 76
10.9.4 Lock Mode ......................................................................................................................................... 76
10.10 RS485 COMMUNICATION ...................................................................................................................... 77
10.11 MULTIDROP MODE................................................................................................................................. 77
10.12 COMMAND LIST ..................................................................................................................................... 78
11 MAINTENANCE .......................................................................................................................................... 81
11.1 TROUBLESHOOTING MINOR PROBLEMS .................................................................................................. 81
11.2 FAIL-SAFE OPERATION ............................................................................................................................ 82
11.3 CLEANING THE LENS ............................................................................................................................... 83
12 APPENDIX..................................................................................................................................................... 84
12.1 DETERMINATION OF EMISSIVITY .............................................................................................................. 84
12.2 TYPICAL EMISSIVITY VALUES ................................................................................................................... 84
13 NOTICES ....................................................................................................................................................... 88
Safety Instructions
10 Rev. D7 Jul 2017 Marathon MM
1 Safety Instructions
This document contains important information, which should be kept at all times with the instrument
during its operational life. Other users of this instrument should be given these instructions with the
instrument. Eventual updates to this information must be added to the original document. The
instrument can only be operated by trained personnel in accordance with these instructions and local
safety regulations.
Acceptable Operation
This instrument is intended only for the measurement of temperature. The instrument is appropriate
for continuous use. The instrument operates reliably in demanding conditions, such as in high
environmental temperatures, as long as the documented technical specifications for all instrument
components are adhered to. Compliance with the operating instructions is necessary to ensure the
expected results.
Unacceptable Operation
The instrument should not be used for medical diagnosis.
Replacement Parts and Accessories
Use only original parts and accessories approved by the manufacturer. The use of other products can
compromise the operation safety and functionality of the instrument.
Safety Instructions
Marathon MM Rev. D7 Jul 2017 11
Safety Symbols
AC (Alternating Current)
DC (Direct Current)
Risk of danger. Important information. See manual.
Hazardous voltage. Risk of electrical shock.
Helpful information regarding the optimal use of the instrument.
Earth ground
Protective ground
Fuse
Normally-open (NO) relay
Normally-closed (NC) relay
Switch or relay contact
DC power supply
Conforms to European Union directive.
Disposal of old instruments should be handled according to professional and
environmental regulations as electronic waste.
Safety Instructions
12 Rev. D7 Jul 2017 Marathon MM
To prevent possible electrical shock, fire, or personal injury follow these guidelines:
Read all safety Information before you use the product.
Use the product only as specified, or the protection supplied by the product can be
compromised.
Carefully read all instructions.
Do not use and disable the product if it is damaged.
Do not use the product if it operates incorrectly.
Do not look directly into the laser with optical tools (for example, binoculars, telescopes,
microscopes). Optical tools can focus the laser and be dangerous to the eye.
Do not look into the laser. Do not point laser directly at persons or animals or indirectly off
reflective surfaces.
Do not use laser viewing glasses as laser protection glasses. Laser viewing glasses are used
only for better visibility of the laser in bright light.
Use the product only as specified or hazardous laser radiation exposure can occur.
Product Description
Marathon MM Rev. D7 Jul 2017 13
2 Product Description
The Marathon MM is a multi-purpose, high performance single color infrared pyrometer with an
extensive feature set, rugged industrial housing and a high level of functionality. The sensor is available
in different spectral responses to accommodate the wide range of industrial applications requiring noncontact temperature measurement. It is intended to be simple to operate, with a user-friendly interface
and well suited to a wide variety of industrial applications.
Each sensor has a rugged stainless steel housing, a rear membrane panel with backlit LCD display, and
a standard through the lens sighting with optional laser target sighting. Alternative to the laser sighting,
a video sighting is offered as an option. The Marathon MM is also available with remotely adjustable
precision focus optics. Users can easily adjust the focus of measurement targets, either by push-button
on the rear of the instrument, or remotely via the RS232/RS485 connection from a PC.
Each model operates as a temperature measurement subsystem consisting of optical elements, spectral
filters, detector, and digital electronics. All components are water-tight NEMA-4 (IP65, IEC529) rated
and are built to operate on a 100 percent duty cycle in industrial environments. Simultaneous analog
and digital outputs consist of standardized signals commonly available for use with computers,
controllers, recorders, alarms, or A/D interfaces.
Technical Data
14 Rev. D7 Jul 2017 Marathon MM
3 Technical Data
3.1 Measurement Specifications
Temperature Range
LT -40 to 800°C (-40 to 1472°F)
G7 300 to 900°C (572 to 1652°F)
G5L 250 to 1650°C (482 to 3002°F)
G5H 450 to 2250°C (842 to 4082°F)
MT 250 to 1100°C (482 to 2012°F)
3M 100 to 600°C (212 to 1112°F)
2ML 300 to 1100°C (572 to 2012°F)
2MH 450 to 2250°C (842 to 4082°F)
1ML 400 to 1740°C (752 to 3164°F)
1MH 540 to 3000°C (1004 to 5432°F)
Measurements at the low end of the temperature range for the 1M models can be
effected by disturbing day light!
Spectral Response
LT 8 to 14 µm
G7 7.9 µm
G5 5 µm
MT 3.9 µm
3M 2.1 to 2.5 µm
2M 1.6 µm
1M 1 µm
Response Time (95%)
LT, MT, G7 120 ms
G5 60 ms
3M 20 ms
1M, 2M 2 ms
Exposure Time1 (95%)
1M, 2M 1 ms
1
The exposure time is the minimum time during which the measured object must be present. The output value of the sensor
can be delayed. (VDI/VDE 3511)
Technical Data
Marathon MM Rev. D7 Jul 2017 15
System Accuracy2
LT ± 1% of reading or ± 1°C for Tmeas > 0°C (32°F)
(whichever is greater)
MT ± 1% of reading for Tmeas > 350°C (662°F)
± 2°C or ± 2% for Tmeas < 350°C (662°F)
(whichever is greater)
G5L, G5H, G7 ± 1% of reading
3M ± 1% of reading for Tmeas > 150°C (302°F)
± 5°C for Tmeas < 150°C (302°F)
2ML ± (0.3% of reading + 2°C)
2MH ± (0.3% of reading + 1°C)
1ML ± (0.3% of reading + 1°C) for Tmeas > 450°C (842°F)
± (2% of reading + 2°C) for Tmeas < 450°C (842°F)
1MH ± (0.3% of reading + 1°C) for Tmeas > 650°C (1202°F)
± (2% of reading + 2°C) for Tmeas < 650°C (1202°F)
Repeatability3
LT, MT, G5, 3M, G7 ± 0.5% of reading or ± 0.5°C, whichever is greater
2ML, 2MH ± (0.1% of reading + 1°C)
1ML ± (0.1% of reading + 1°C) for Tmeas > 450°C (842°F)
± (1% of reading + 1°C) for Tmeas < 450°C (842°F)
1MH ± (0.1% of reading + 1°C) for Tmeas > 650°C (1202°F)
± (1% of reading + 1°C) for Tmeas < 650°C (1202°F)
Temperature Resolution (mA output)
2MH, 1MH 0.2 K
all other models 0.1 K
Noise Equivalent Temperature (NETD)
LT 0.1 K at Tobj = 23°C (73°F), Tamb = 23°C (74°F)
3M 0.1 K at Tobj = 200°C (392°F), Tamb = 25°C (77°F)
MT, G5, G7 0.5 K at Tobj = 10% of full measurement range, Tamb = 25°C (77°F)
2M, 1M 0.5 K at Tobj = 10% of full measurement range, Tamb = 25°C (77°F)
Response time = Instrument Response time
Emissivity 0.100 to 1.150, in 0.001 increments
Signal Processing Peak hold, valley hold, averaging, advanced peak hold,
advanced valley hold, ambient background temperature
compensation
2
at 23°C ±5°C (73°F ±9°F), emissivity = 1.0, and time response 1.0 s
3
at 23°C ±5°C (73°F ±9°F)
Technical Data
16 Rev. D7 Jul 2017 Marathon MM
3.2 Optical Specifications
In all cases, make sure the target completely fills the measurement spot, see section 6.1.1 Distance to
Object, page 26.
The actual spot size for any distance, when the unit is at focus distance, can be calculated by using the
following formula. Divide the distance D by your model’s D:S number. For example, for a unit with D:S
= 300:1, if the sensor is 2200 mm (86 in.) from the target, divide 2200 by 300 (86 by 300), which gives you
a target spot size of approximately 7.3 mm (0.29 in.).
Figure 1: Spot Size Chart
All target spot sizes indicated in the optical diagrams are based on 90% energy.
3.2.1 Variable Focus
Model
Focus
Focus Range
Optical
Resolution D:S *
Smallest Spot Size
LT, MT, G5, 3M
VF1
200 mm (7.9 in.) to 2200 mm (86.6 in.)
70:1
2.9 mm @ 200 mm
(0.11 in. @ 7.9 in.)
G7
VF1
200 mm (7.9 in.) to 2200 mm (86.6 in.)
100:1
2 mm @ 200 mm
(0.08 in. @ 7.9 in.)
1ML, 2ML
VF1
300 mm (11.8 in.) to 2200 mm (86.6 in.)
160:1
1.9 mm @ 300 mm
(0.07 in. @ 11.8 in.)
1MH, 2MH
VF1
300 mm (11.8 in.) to 2200 mm (86.6 in.)
300:1
1 mm @ 300 mm
(0.04 in. @ 11.8 in.)
* Optical Resolution is achieved for each focal point in the focus range
Mean Time Between Failures (MTBF) 10,000 operations (at Tamb = 23°C/74°F)
D = Distance
S = Spot size
Technical Data
Marathon MM Rev. D7 Jul 2017 17
3.2.2 Fixed Focus
Optical Resolution D:S
LT, MT, G5, 3M 70:1
G7 100:1
Available Optics
LT, MT, G5, 3M, G7 SF1, SF2, SF3
LT, 3M CF1
The focus distance is measured from the front end of the sensor. For units with
Air/Water Cooled Housing you have to subtract 34.5 mm (1.358 in) from the focus
distance. This is very important especially for sensors with close focus optic!
Technical Data
18 Rev. D7 Jul 2017 Marathon MM
SF … Standard Focus, CF … Close Focus
* specified D:S ratio at focus point only
Table 1: Optical Diagrams for D:S = 70:1
Technical Data
Marathon MM Rev. D7 Jul 2017 19
SF … Standard Focus, CF … Close Focus
* D:S = 100:1 at focus point
Table 3: Optical Diagrams for D:S = 100:1
Technical Data
20 Rev. D7 Jul 2017 Marathon MM
SF … Standard Focus, CF … Close Focus
* D:S = 160:1 at focus point
Table 2: Optical Diagrams for D:S = 160:1
Technical Data
Marathon MM Rev. D7 Jul 2017 21
SF … Standard Focus, CF … Close Focus
* D:S = 300:1 at focus point
Table 3: Optical Diagrams for D:S = 300:1
Technical Data
22 Rev. D7 Jul 2017 Marathon MM
3.3 Electrical Specifications
Power Supply 24 VDC ± 20%, min. 500 mA
Outputs
Analog 0 - 20 mA, 4 - 20 mA (active)
14 bit resolution
max. current loop impedance: 500 Ω
RS485 Interface networkable to 32 sensors
Baud rate: 300, 1200, 2400, 9600, 19200, 38400 (default), 57600,
115200
(max. 38400 Baud in 2-wire mode)
Data format: 8 bit, no parity, 1 stop bit,
4-wire mode (full-duplex) or 2-wire mode (half duplex),
selectable via control panel or software
Relay Contacts max. 48 V, 300 mA, response time < 2 ms,
(software programmable)
Display 5 digit backlit LCD display
External Input
Input Voltage 0 to 5 VDC
functions: trigger, laser ON/OFF switching, ambient
background temperature compensation, or emissivity setting,
see section 7.4.3 External Input page 44.
3.4 Environmental Specifications
Environmental rating NEMA-4 / IEC 529, IP 65 (also with video option)
Relative Humidity 10% to 95% non-condensing
Storage Temperature -20 to 70°C (-4 to 158°F)
Ambient Temperature 5 to 65°C (41 to 149°F) without cooling
with video 5 to 50°C (41 to 122°F) without cooling
with air cooling 10 to 120°C (50 to 250°F)
with water cooling 10 to 175°C (50 to 350°F)
with ThermoJacket 10 to 315°C (50 to 600°F) water cooled
Warm up Period 20 min.
Vibration MIL-STD-810D (IEC 68-2-6) 2 G, 10 - 150 Hz, 3 axis
Mechanical Shock MIL-STD-810D (IEC 68-2-27) 5 G, 11 ms duration, 3 axis
Weight 0.7 kg (1.54 lb)
Technical Data
Marathon MM Rev. D7 Jul 2017 23
3.5 Dimensions
Figure 2: Dimensions of Sensor
For the dimensional drawing of the Fixed Mounting Bracket, see section 9.2 Fixed Mounting Bracket,
page 57.
3.6 Scope of Delivery
The scope of delivery includes the following:
• Sensor with through-the-lens sighting
• Operating Instructions
• DataTemp Multidrop Software
• Mounting nut made from stainless steel (XXXMMACMN)
• Fixed mounting bracket made from stainless steel (XXXMMACFB)
Basics
24 Rev. D7 Jul 2017 Marathon MM
4 Basics
4.1 Measurement of Infrared Temperature
Everything emits an amount of infrared radiation according to its surface temperature. The intensity of
the infrared radiation changes according to the temperature of the object. Depending on the material
and surface properties, the emitted radiation lies in a wavelength spectrum of approximately 1 to 20
µm. The intensity of the infrared radiation (”heat radiation”) is dependent on the material. For many
substances this material-dependent constant is known. It is referred to as ”emissivity value”, see section
12.2 Typical Emissivity Values, page 84.
Infrared thermometers are optical-electronic sensors. These sensors are able to detect ”radiation of
heat”. Infrared thermometers are made up of a lens, a spectral filter, a sensor, and an electronic signal
processing unit. The task of the spectral filter is to select the wavelength spectrum of interest. The sensor
converts the infrared radiation into an electrical signal. The signal processing electronics analyze the
electrical signals and convert it into a temperature measurement. As the intensity of the emitted infrared
radiation is dependent on the material, the required emissivity can be selected on the sensor.
The biggest advantage of the infrared thermometer is its ability to measure temperature without
touching an object. Consequently, surface temperatures of moving or hard to reach objects can easily be
measured.
4.2 Emissivity of Target Object
Determine the emissivity of the target object as described in appendix 12.1 Determination of Emissivity,
page 84. If emissivity is low, measured results could be falsified by interfering infrared radiation from
background objects (such as heating systems, flames, fireclay bricks, etc. close beside or behind the
target object). This type of problem can occur when measuring reflecting surfaces and very thin
materials such as plastic films and glass.
This measuring error can be reduced to a minimum if particular care is taken during installation, and
the sensing head is shielded from these reflecting radiation sources.
Environment
Marathon MM Rev. D7 Jul 2017 25
5 Environment
Sensor location depends on the application. Before deciding on a location, you need to be aware of the
ambient temperature of the location, the atmospheric quality of the location, and the possible
electromagnetic interference in that location, according to the sections described above. If you plan to
use air purging, you need to have an air connection available. If you are installing the sensor in a
ThermoJacket accessory, you should use the appropriate mounting device. Also, wiring and conduit
runs must be considered, including computer wiring and connections, if used.
5.1 Ambient Temperature
The sensor is designed for measurements in ambient temperatures between 5°C and 65°C (41 to 149°F).
A water or air cooled housing is available as option to extend the operating range to 120°C (250°F) with
air cooling and to 175°C (350°F) with water cooling.
In ambient conditions up to 315°C (600°F), the ThermoJacket housing should be used. When using the
ThermoJacket, it is strongly recommended to use the supplied air purge to avoid condensation on the
lens.
5.2 Atmospheric Quality
If the lens gets too dirty, it cannot detect enough infrared energy to measure accurately. It is good
practice to always keep the lens clean. The air purge helps keep contaminants from building up on the
lens. If you use the air purge accessory, make sure a filtered air supply with clean dry air at the correct
air pressure is installed before proceeding with the sensor installation.
5.3 Electrical Interference
To minimize measurement errors due to electrical or electromagnetic interference or “noise” be aware
of the following:
Mount the electronics enclosure as far away as possible from potential sources of electrical
interference such as motorized equipment producing large step load changes.
Use shielded wire for all input and output connections.
Make sure the shield wire from the electronics to terminal block cable is earth grounded.
For additional protection, use conduit for the external connections. Solid conduit is better than
flexible conduit in high noise environments.
Do not run AC power in the same conduit as the sensor signal wiring.
When installing the sensor, check for any high-intensity discharge lamps or heaters that
may be in the field of view (either background or reflected on a shiny target). Reflected
heat sources can cause a sensor to give erroneous readings.
Installation
26 Rev. D7 Jul 2017 Marathon MM
6 Installation
6.1 Mechanical Installation
After all preparations are complete, you can install the sensor. How and where you anchor the sensor
depends on the type of surface and the type of bracket you are using. You can mount the sensor through
a hole, on a bracket of your own design, or on the available bracket accessory.
6.1.1 Distance to Object
The desired spot size on the target will determine the maximum measurement distance and the
necessary focus length of the optical module. To avoid erroneous readings the target spot size must
contain the entire field of view of the sensor. Consequently, the sensor must be positioned so the field
of view is the same as or smaller than the desired target size. For a list indicating the available focus
models and their parameters, see section 3.2 Optical Specifications, page 16.
Figure 3: Proper Sensor Placement
6.1.2 Variable Focus
The optional variable focus allows adjustment of the focus length of the sensor optics. Using sensors
with this feature requires that the correct focal distance be set on the sensor. To determine the correct
focal distance for the sensor, measure the distance in millimeters from the face of the sensor to the target.
Set the focal distance to be equal to the measured distance. It is possible to set the focal distance either
on the control panel of the sensor or through the DataTemp Multidrop Software.
The factory default focal distance is 600 mm (23.6 in.).
Target greater than spot size
Target equal to spot size
Target smaller than spot size
best
critical
incorrect
Background
Sensor
Installation
Marathon MM Rev. D7 Jul 2017 27
6.1.3 Viewing Angles
The sensor head can be placed at any angle from the target up to 30°.
Figure 4: Acceptable Sensor Viewing Angles
Best
90° to target
Good
30° to 90° to target
Bad
0° to 30° to target
Acceptable
Angles
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