
CLKT C-Range
Infrared Window
for outdoor applications
Increase the safety and speed 
of electrical thermography
If you are concerned about arc-flash but 
wish to continue with your infrared thermography program, infrared windows are 
the answer. These arc-resistant, outdoor 
certified, infrared windows allow thermal, 
ultraviolet, visual and fusion technologies to 
be used without exposing personnel to live 
equipment.
All infrared windows from Fluke use the unique 
Quadraband™ multispectral optic, allowing 
inspection with any camera for total flexibility both 
now and in the future.
 Engineered and tested to withstand electric-arcs 
•
up to 50 kA for 30 cycles.
 Certified by UL & CSA for Type 3/12 (Outdoor) 
•
environments in North America and Canada, the 
C-Range windows are tested to withstand the 
long term aging effects of UV exposure.
 Certified by SIRA Certification IP65 (Outdoor) 
•
environments in Europe.
 The CLIRVU® coating—exclusive to Fluke 
•
Windows—seals the optic prior to assembly to 
protect against moisture degradation.
 Own a Fluke Camera? The Quadraband™ 
•
optic is IR-Fusion® compatible, allowing the 
thermographer to see potential problems in 
visual light and thermographic mode.
 Got more than one window per panel? 
•
Each C-Range window is delivered with an 
identification plate attached for unique, on-site 
numbering for rapid location confirmation and 
faster repairs.
 Each infrared window comes complete with a 
•
security access key, installation instructions and 
self-adhesive drilling template.
Technical Data
Quadraband
OPTIC TECHnOLOGY
Exclusive to Fluke IR Windows, 
allows you to inspect your equipment with four different types 
of cameras. Provides maximum 
flexibility to upgrade or swap out 
inspection cameras without any 
IR Window replacement. No other 
IR Windows manufacturer gives 
you that flexibility.
AutoGround
Automatically grounds at installation for maximum safety and 
compliance. No additional steps 
or testing is required. Only available on Fluke IR Windows.
™
™

Detailed specifications
3460346 FLK-050-CLKT 3460387 FLK-075-CLKT 3460439 FLK-100-CLKT
Optic data 
Crystal insert diameter 50 mm (1.97 in) 75 mm (2.96 in) 100 mm (3.94 in) 
Viewing aperture diameter 43 mm (1.7 in) 68 mm (2.7 in) 89 mm (3.5 in) 
Viewing aperture area 1452 mm2 (2.25 sq in) 3632 mm2 (5.63 sq in) 6322 mm2 (9.79 sq in) 
Thickness 2 mm (0.08 in) 2 mm (0.08 in) 4 mm (0.16 in) 
CLIRVU coating Yes 
Shortwave IR capable Yes 
Midwave IR capable Yes 
Longwave IR capable Yes 
Ultraviolet (UV) capable Yes 
Visual capable Yes 
Fusion capable Yes
Why is available area important? 
Understanding the difference between “Optic Diameter” 
and “Available Area” gives the thermographer a measure 
of how much infrared energy is passing through the 
Mesh grids may have a larger “optic diameter” but the 
grid itself blocks the IR signal. The amount of radiation 
available to the camera via mesh windows is significantly 
reduced and the signal may be irregular.
window. The more energy, the better the reading. The 
entire area of a crystal IR Window is available for infrared 
transmission for optimum repeatable results.
Underwriters Laboratories (UL) recognized Yes
UL50 environmental Type 3/12 
UL746C N/A (Polymer Free) 
UL94 N/A (Polymer Free)
Canadian Standards Association (CSA) approval Yes
Environmental Type 3/12
KEMA (Arc-Testing)
ANSI C37.20.7 50 kA for 30 cycles @60 Hz 
EEMACS 14-1 Type-B 40 kA for 30 cycles @60 Hz
ASTA (Arc-Testing)
IEC 62271 20 kA for 5 cycles @50 Hz
TUV
Cyclic humidity withstand Yes 
Vibration withstand Yes
NEMKO
Resistance of insulating materials to 100° Yes 
Resistance of insulating material to ball pressure (Brinell) Yes 
Glow-wire test 650 °C Yes
Lloyds Register
Up to 11 kV marine switchgear, indoor or outdoor Yes
2 Fluke Corporation   CLKT C-Range Infrared Window for outdoor applications

General specifications
Maximum temperature Gaskets: 250 °C (482 °F)
Body: 659 °C (1219 °F) 
Optic: 1400 °C (2552 °F)
Gaskets Low smoke and fume (LSF) compliant silicone 
IP rating IP65 
NEMA rating Type 3/12 (UL and CSA Third Party Certified) 
Vibration rating IEC60068-2-6 
Humidity rating IEC60068-2-3 
Pull-out strength Up to 630 kg (1388 lb) 
Warranty Lifetime replacement against manufacturing defects
Ordering information
Crystal insert size 50 mm (2 in) 75 mm (3 in) 100 mm (4 in)
3460346 
FLK-050-CLKT 
Kwik-twist aluminium cover  KT KT KT
3460387 
FLK-075-CLKT
3460439 
FLK-100-CLKT
Basic Field of View (FOV) calculation, 
F = 6 x D
Included with product
IR Windows are supplied complete, assembled and ready for installation. 
In addition to the IR Window each carton contains an installation CD, 
self-adhesive drilling template, security access key, warranty statement.
Fluke. Not just infrared. 
  Infrared you can use.
Fluke Corporation
PO Box 9090, Everett, WA 98206 U.S.A.
Fluke Europe B.V.
PO Box 1186, 5602 BD  
Eindhoven, The Netherlands
For more information call:
In the U.S.A. (800) 443-5853 or  
Fax (425) 446-5116 
In Europe/M-East/Africa +31 (0) 40 2675 200 or  
Fax +31 (0) 40 2675 222 
In Canada (800)-36-FLUKE or  
Fax (905) 890-6866 
From other countries +1 (425) 446-5500 or  
Fax +1 (425) 446-5116 
Web access: http://www.fluke.com
©2009-2010 Fluke Corporation. 
Specifications subject to change without notice. 
Printed in U.S.A. 7/2010 3504172D D -EN-N
Modification of this document is not permitted  
without written permission from Fluke Corporation.
TM
3 Fluke Corporation   CLKT C-Range Infrared Window for outdoor applications