General IRT850K User manual

50:1 ULTRA-WIDE RANGE
IR THERMOMETER
WITH “K PORT
USER’S MANUAL
IRT850K
Please read this manual carefully and thoroughly before using this product.
99 Washington Street
Melrose, MA 02176
Phone [phone]
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com

TABLE OF CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Key Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
What’s in the Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Product verview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Install Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
perating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 –8
Basic peration in Scan Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 –6
Accounting for Emissivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
ther perating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 –8
ther Display Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Maintenance Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Appendix I: How to Make Accurate IR Measurements . . . . . . . . . . . . . . 10 – 11
Appendix II: Emissivities of Common Materials. . . . . . . . . . . . . . . . . . . . . . . . 12
Manual del Usuario en Español . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 – 24
Manuel de L'utilisateur en Français . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 – 38
INTRODUCTION
Thank you for purchasing General Tools & Instruments’ IRT850K 50:1 Ultra-Wide Range IR
Thermometer with “K” Port. Please read this user’s manual carefully and thoroughly before using
the instrument.
The IRT850K is a specialized instrument that can measure the temperature of a very hot or cold
object or surface (the target) by using an IR sensor to measure its thermal radiation from a safe
distance. Dual laser beams help define the size of the target. With a distance-to-spot (D:S) ratio
of 50:1; the IR sensor can measure the temperature of a target (spot) 1 ft. in diameter from 50 ft.
away with a basic accuracy of ±1.8°F near room temperature and an accuracy of ±(2% of the
reading or 3.6°F) elsewhere in the measurement range. The IRT850K’s IR measurement range is
-76° to 2732°F (-60° to 1500° ).
The IRT also has a socket for an optional “K” type thermocouple probe with a measurement
range as wide as -83.2° to 2552°F (-64° to 1400° ).
The IRT850K is designed for use in heavy industrial sectors such as steel and chemical
manufacturing, petroleum refining, steam generation, and power generation and transmission.
2

SAFETY INSTRUCTIONS
CAUTI N - Performing procedures other than those specified in this manual may result in
dangerous radiation exposure.
The IRT850K is a lass 2 laser product that emits less than 1 mW of radiation at a wavelength
between 635 and 660nm. Avoid looking directly at the laser pointers. U.S. law prohibits pointing a
laser beam at aircraft; doing so is punishable by a fine of up to $10,000 and imprisonment.
The lasers may cause discomfort if viewed directly. Your eyes’ natural aversion reflex will prevent
you from looking at the beam long enough to cause harm. As a precaution, keep the IRT850K out
of the hands of children, especially if you have pets.
Never stare at a laser beam through binoculars or a magnifying glass.
Do not operate the IRT in the presence of flammable or explosive gases or in environments full of
dust or static electricity.
Do not operate the unit near a source of a strong electromagnetic field, such as an arc welder or
an induction heater.
Be careful not to burn yourself when attaching a thermocouple probe to a hot surface.
KEY FEATURES
• Extremely wide measurement range
• Adjustable emissivity • Dual targeting lasers
• Port for optional “K” type thermocouple for making contact temperature
measurements
• Releasing trigger automatically holds measurement
• Measurement Lock mode eliminates need to keep squeezing trigger to make multiple
measurements
• Stores/recalls 24 data sets (measured temperature + emissivity setting)
• Min/Max/Avg/Dif displays
• Adjustable Hi and Lo temperature alarm setpoints
• Large backlit dual readout L D • White LED flashlight • Auto power off
• ° /°F, lasers and flashlight on/off, and backlight on/off buttons
• Battery charge indicator • Tripod mount • E approved
• 1 year limited warranty
WHAT S IN THE PACKAGE
The IRT850K comes in a hard plastic protective case along with this user’s manual.
The only optional accessories for the IRT850K available from General are “K” type
thermocouples.
3

PRODUCT OVERVIEW
Figure 1 shows all of the controls, indicators, connectors and other physical features of the
IRT850K. Figure 2 shows a typical measurement display. Familiarize yourself with the positions
and functions of all controls and key components and the meaning of all display indications
before moving on to the Setup Instructions and Operating Instructions.
Fig. 1. The IRT850K’s controls and indicators
and other physical features
1. Emis. (Emissivity) button.
2.  °C/°F multi-function button. Used to
a) change measurement unit, b) turn targeting lasers and LED flashlight on and off,
c) decrease Hi and Lo alarm setpoints and d) decrement memory location number of recalled data
3. L D
4.  Lock multi-function button. Used to a) enter/exit Measurement Lock mode, b) turn L D
backlight on and off, c) increase Hi and Lo alarm setpoints and d) increment memory location
number of recalled data
5. Mode button. Selects display mode and operating mode
6. Measurement trigger 7. Battery compartment
8. IR sensor and lens 9. Laser apertures
10. LED flashlight 11. Socket for “K” type thermocouple probe with spade lugs
12. Tripod mount 13. Laser Identification/ ertification/Warning/Safety labels
Fig. 2. A typical measurement screen.
Note the main (upper) and
secondary (lower) readouts.
4
1. Emis.
button
3. L D
4.  Lock
button
5. Mode
button
11. “K” probe
socket
6. Measurement
trigger
9. Laser
apertures
8. IR senor
& lens
7. Battery
compartment
12. Tripod mount
10. LED
flashlight
13. Laser labels (see below right)
2.  ° /°F
button

SETUP INSTRUCTIONS
INSTALL BATTERIES
The IRT850K is ready for use after you install two “AAA” batteries (not included) in the
instrument’s grip. To open the battery compartment (Fig. 1, allout 7), pull the top of its hinged
cover away from the grip. Then install the two batteries in the compartment, using the + and –
marks inside it as a guide. lose the compartment by swinging the cover back to its original
position and snapping it shut.
OPERATING INSTRUCTIONS
BASIC OPERATION IN SCAN MODE
The IRT850K’s default operating mode is to scan a target object’s surface and display its
temperature.
To make a quick measurement, point the infrared lens on the front of the instrument (Fig. 1,
allout 8) at a target and squeeze and hold the measurement trigger ( allout 6). The temperature
of the target will instantly appear on the main (upper) readout in the thermometer’s default unit
of degrees Fahrenheit (°F). Before releasing the trigger, note the SCAN icon on the top line of
the display.
Now release the trigger and note that: 1) the main readout will hold the reading for 1 minute (as
indicated by the H LD indication at the upper left of the L D); and 2) the IRT will briefly display
the term oFF and then power off. This Auto Power Off (APO) function conserves battery life.
To make an accurate measurement, use the IRT850K’s dual laser beams to define the
diameter of the target. Unlike convergent lasers used to identify the spot distance, the IR850K’s
dual lasers are designed to highlight the spot diameter beyond the focal point (see figure
below)—and therefore the target area—at any distance beyond the spot. This capability is not
just convenient, but also critical in making accurate temperature measurements.
Fig. 3. The IRT850K’s field of view, created by dual diverging laser beams
All IR thermometers, including the IRT850K, take the average temperature of all objects within a
circular target area. Depending on the distance to the target, the target area may include both the
target and background objects in the thermometer’s field of view. If background objects in the
field of view are cooler than the target, the measured temperature will be lower than the target’s
5
1 ft. 1.5 ft. 2 ft.
50 ft. 75 ft. 100 ft.

actual temperature. If background objects are hotter than the target, the measured temperature
will be higher than the target’s actual temperature. The IRT850K’s very large D:S ratio of 50:1
enables measurement of very high- or –low temperature objects from a safe distance.
To eliminate measurement error, move the IRT850K close enough to the target so it is the
only object in the field of view. (See Appendix I for an illustrative example.)
ACCOUNTING FOR EMISSIVITY
Emissivity is the ability of an object to reflect or absorb IR radiation (energy). Because the
IRT850K measures the amount of infrared energy emitted by a surface, its measurements are
most accurate when they take into account the characteristic emissivity of the target material.
A perfectly absorbent surface (called a black body) has an emissivity (represented by the Greek
letter ε) of 1; it absorbs 100% of the thermal energy hitting it. An object with an emissivity of 0.8
absorbs 80% of IR energy and reflects 20% of it. All emissivity values fall between 0 and 1; as a
rule, the shinier the surface, the lower its emissivity. The default emissivity setting of the IRT850K
is 0.95.
To maximize the accuracy of IRT850K measurements, you should enter the actual emissivity of
the target surface using the front-panel buttons. To do so, first determine the emissivity of the
surface whose temperature you wish to measure from the list in Appendix II. ompensating for
emissivity will particularly improve the accuracy of measurements of surfaces with emissivities
nearer to zero than to the IRT850K's default setting of 0.95.
To enter an emissivity value, begin by pressing the Emis. button (Fig. 1, allout 1). Then enter
the emissivity of your target by using the °C/°F and Lock buttons to change the reading on
the secondary (lower) readout from the default 0.95. The IRT850K’s emissivity setting can be
adjusted from 0.10 to 1.0 in steps of 0.01. Once you have reached the correct value, press the
Mode button (Fig. 1, allout 5) to store the setting as the new default.
If your target’s material is not listed in the table in Appendix II, you can determine its emissivity
by using the IRT850K to do the following:
1. Measure the temperature of the target with an optional “K” type thermocouple probe. This
requires switching to operation in PRB (“K” port) mode. Instructions for entering and
operating in this mode can be found on p. 7.
2. Return to operating in Scan mode. Use the Emis., °C/°F and Lock buttons to change
the emissivity setting until the temperature reading in Scan mode matches the one
obtained in PRB mode. When both readings are the same, the displayed emissivity value is
the correct one for your object or surface at that temperature.
OTHER OPERATING MODES
The Mode button also serves as the gateway for entering the
IRT850K’s other operating modes. Pressing the button repeatedly
steps through those modes in the sequence shown in Fig. 3.
Fig. 3. The functions available
through the IRT850K’s Mode button
6

εEmissivity entering mode
MAX Secondary readout displays the maximum temperature sensed during a single
measurement session (In Scan mode, a measurement session begins when the trigger is
squeezed and ends when the APO function powers off the instrument.)
MIN Secondary readout displays the minimum temperature during the current measurement
session
dIF Secondary readout displays the largest temperature difference during the current session
AVG Secondary readout displays the average temperature sensed during the current session
HAL Secondary readout displays the high alarm setpoint. To change the setpoint, use the
°C/°F and Lock buttons to enter a new temperature threshold and then squeeze the
trigger to save the setting.
LAL Secondary readout displays the low alarm setpoint. To change the setpoint, use the
°C/°F and Lock buttons to enter a new temperature threshold and then squeeze the
trigger to save the setting.
PRB Secondary readout displays the temperature sensed by an optional “K” type
thermocouple plugged into the socket on the right side of the grip (Fig. 1, allout 11). To
make a contact measurement using a thermocouple, place its bead or stem on or in
the target. To view the minimum and maximum temperature sensed during a
measurement session with an external probe, press and hold the °C/°F and Lock
buttons, respectively.
M00 Memory mode. To save a measurement, press the Mode button after making the
measurement. To recall a measurement or set of measurements, use the °C/°F and
Lock buttons to scroll through the data sets stored in memory.
Fig 4 shows a typical IRT850K memory screen. It shows that a
measurement of 1854°F on an object with an emissivity of 0.95 was
made and stored in memory location 02. In addition, the “LOW” icon on
the screen reveals that when the reading was stored it was below the
instrument’s low alarm setpoint (LAL). The IRT850K can store up to
24 pairs of temperature measurements/emissivity values.
Fig. 4. A typical IRT850K memory screen
Two other functions are available whenever the IRT850K is operating in MAX, MIN, dIF or AVG
mode.
1. Pressing the Lock button puts the instrument into LO K mode. In this mode, the
thermometer makes and displays measurements continuously for up to one hour without
pulling the measurement trigger. In LO K mode, the “wave” portion of the S AN icon on
the top line of the L D blinks continuously and the time over which MAX, MIN, dIF and AVG
readings are calculated is extended to 1 hour from the APO interval of 1 minute.
To unlock the trigger, press the Lock button again.
7

2. Pressing the °C/°F button changes the instrument’s default temperature unit from
° to °F. To return to using ° units, press the °C/°F button again.
Another two functions are available whenever the IRT850K is operating in any mode:
1. To toggle the L D backlight on and off, press the Lock button while squeezing and
holding the measurement trigger.
2. To shut off the twin lasers and LED flashlight, press the °C/°F button while squeezing
and holding the trigger. To turn on the lasers and flashlight, press the °C/°F button
again. Turning off the lasers and flashlight extends battery life.
OTHER DISPLAY INDICATIONS
Battery messages. Fig. 4 shows three of several other possible icons and alerts that could appear
on the IRT850K’s display. They are the and icons (the symbols for the “Lasers and
flashlight on” and “Backlight on” states discussed in the last section) and the icon.
Whenever the icon is on-screen, the IRT850K’s batteries are still sufficiently charged to
enable accurate measurements. By contrast, the icon indicates that the batteries have
discharged enough to warrant replacing them immediately, although they still have enough
charge to support accurate measurements. Once the icon appears, however, the
thermometer’s batteries have been fully discharged, making accurate measurements impossible.
To replace the batteries, follow the Setup Instructions on p. 5.
Alarm messages. The following four types of alarm messages could appear on the IRT850K’s
display.
“Hi” or “Low” is displayed when the measured temperature is higher than
the HAL setpoint or lower than the LAL setpoint.
“Er2” is displayed when the thermometer is exposed to rapid changes in
ambient temperature. When this message appears, try giving the
thermometer some time (30 minutes or more) to adjust to the new working
temperature after it has stabilized.“Er3” appears when the ambient
temperature falls below 32°F (0° ) or rises above 122°F (50° ).
If this error message (or an “Error 5~9” message) appears, the IRT850K
must be reset. To do so, wait up to 1 minute for the APO function to engage
and then remove the batteries. Then wait at least one minute more, reinsert
the batteries, and attempt to make a measurement in Scan mode. If the error
message remains, contact General’s ustomer Service department for help.
“Hi” or “Lo” is the message displayed if the target’s temperature is outside
the IRT850K’s measurement range of -76° to 2732°F (-60° to 1500° ).
8

SPECIFICATIONS
IRT Distance to Spot (D:S) Ratio: 50:1
IRT Measurement Range: -76° to 2732°F (-60° to 1500° )
IRT Measurement Accuracy:
±1.8°F (1.0° ) from 59° to 95°F (15° to 35° ) @ Tamb of 77°F
(25° ); ±(2% of reading or 3.6°F (2° )), whichever is greater,
from -27° to 59°F (-33° to 15° ) and from 95° to 2732°F (35° to
1500° ) @ Tamb of 73.4° ± 5.4°F (23° ±3° )
IRT Emissivity: Adjustable from 0.1 to 1.0 in 0.01 steps with default of 0.95
“K” Port Measurement Range: -83° to 2552°F (-64° to 1400° )
“K” Port Measurement Accuracy: ±(2% of reading +3.6°F/2° ) or ±5.4°F (3° ), whichever is
greater, @ Tamb of 73.4° ± 10.8°F (23° ±6° )
IRT/”K” Port Measurement 0.1° (F or ) below 1000°; 1° at and above 1000°
Resolution:
Display Type, Size: 2 in. (51mm) diagonal backlit L D with 0.5 in. (13mm) high
digits on main readout
Response Time: < 1 second
Laser Power: <1mW ( lass 2) @ wavelength of 635 to 660nm
Auto Power Off Trigger: 1 minute of front-panel inactivity in Scan (IRT) mode; 12
minutes of front-panel inactivity in PRB (“K” port) mode
Operating Temperature: 32° to 122°F (0° to 50° )
Dimensions: 7.99 x 7.76 x 1.85 in. (203 x 197 x 47mm)
Weight (including batteries): 13.6 oz. (386g)
Power Source: (2) “AAA” batteries (not included)
Battery Life: 180 hours (typical) of continuous use with lasers and
backlight off
MAINTENANCE TIPS
The IRT850K cannot make accurate measurements if there is glass or plastic between it and the
target.
lean the lens of the IR sensor lens (Fig. 1, allout 8) often—but never use a solvent.
Abrupt temperature changes will cause condensation and possible vapor penetration. lean the
L D after the vapor evaporates. Blow off loose particles with clean, compressed air. Gently brush
remaining debris away with a lens hair brush.
To clean the housing, use a moist cotton swab or wet sponge. Avoid excessive amounts of water
and corrosive gas or liquids.
Remove the batteries if you do not expect to use the IRT for an extended period of time (months
or years).
Do not drop or disassemble the instrument or immerse it in water.
9

WARRANTY INFORMATION
General Tools & Instruments’ (General’s) IRT850K 50:1 Ultra-Wide Range IR Thermometer with
“K” Port is warranted to the original purchaser to be free from defects in material and
workmanship for a period of one year. Subject to certain restrictions, General will repair or
replace this instrument if, after examination, the company determines it to be defective in
material or workmanship. The warranty period begins on the date of purchase. You are
encouraged to register your product online. General will extend your warranty an additional 60
days if you register at www.generaltools.com/ProductRegistry.
This limited warranty does not apply to damages that General determines to be from an
attempted repair by non-authorized personnel or misuse, alterations, normal wear and tear, or
accidental damage. The defective unit must be returned to General Tools & Instruments or to a
General-authorized service center, freight prepaid and insured.
Acceptance of the exclusive repair and replacement remedies described herein is a condition of
the contract for purchase of this product. In no event shall General be liable for any incidental,
special, consequential or punitive damages, or for any cost, attorneys’ fees, expenses, or losses
alleged to be a consequence of any damage due to failure of, or defect in any product including,
but not limited to, any claims for loss of profits.
Register now at www.generaltools.com/ProductRegistry to receive a 60-day extension to your
warranty.
RETURN FOR REPAIR POLICY
Every effort has been made to provide you with a reliable product of superior quality. However, in
the event your instrument requires repair, please contact our ustomer Service to obtain an RGA
(Return Goods Authorization) number before forwarding the unit via prepaid freight to the
attention of our Service enter at this address:
Remember to include a copy of your proof of purchase, your return address, and your phone
number and/or e-mail address.
APPENDIX I
The IRT850K’s field of view
10
S
ft.
cm
D
D:S=50:1
15@750 30@1500
1@50 2@100 3@150
45@2250

HOW TO MAKE ACCURATE IR MEASUREMENTS
The IRT850K has a distance-to-spot (D:S) ratio of 50:1. That means that the target area (spot)
whose infrared radiation (temperature) is being measured increases in diameter by 1 inch for
every 50 inches you move away from the target. onversely, the diameter of the target area
measured decreases by 1 inch for every 50 inches you move closer to the target.
All IR thermometers (IRTs), including the IRT850K, take the average temperature of all objects
within a circular target area (spot). Although the distance “D” in the D:S ratio is defined as a
linear value and the “S” defines the diameter of the spot (see figure on previous page), the
critical parameter is the target area. Depending on the distance to the target (the object whose
temperature you want to measure), the target area may include both the target and background
objects near or behind the thermometer’s field of view, which defines the target area or spot.
To explain the relationship between D:S ratio and measurement accuracy, consider how the
IRT850K would be used to measure the temperature of a small A motor suspected of
overheating. The motor measures approximately 1 ft x 1 ft, so it has an area of 1 ft2. If the
IRT850K is used to make the measurement from 100 ft. away, the reading will have a large error.
At this distance, the target area is 2 ft2. Therefore, the IRT850K will measure not just the
temperature of the motor, but also the temperature of the physical surroundings in its field of
view, and average the two readings.
How inaccurate would the measurement be? If the motor’s operating temperature is 200°F and
the background temperature is 75°F, and the motor’s area is half the target area at the
measurement distance, the following equation gives the average temperature of the target area:
Tavg = (Tmotor + Tbackground) ÷ 2
Solving for Tavg, we get (200 + 75) ÷ 2 or 137.5°F., which is what the IRT850K would display. In
other words, trying to measure the temperature of the motor from 100 ft. away introduced an error
of (200-137.5) ÷ 200, or 31% into the measurement. In this case, the measured temperature was
31% below the motor’s actual temperature because the background is cooler than the motor.
To eliminate measurement error, the IRT must be moved close enough so the motor is the only
object in the target area (see figure below). For a motor with an area of 1 ft2and using an IRT
with a D:S ratio of 50:1, the
optimum measurement distance
would be 50 ft.
For best results, the targeted
area (spot) should fall within the
target’s boundaries, as in the
figure at right.
Measuring a motor’s
temperature from the wrong
(top) and right (bottom)
distance
11
wall

APPENDIX II
EMISSIVITIES OF COMMON MATERIALS
Material Emissivity Material Emissivity
Aluminum 0.30 Glass 0.90 to 0.95
Asphalt 0.95 Iron Oxides 0.78 to 0.82
oncrete 0.95 Paint 0.80 to 0.95
Asbestos 0.95 Plastic 0.85 to 0.95
eramics 0.95 Paper 0.70 to 0.94
Brass 0.50 Plaster 0.80 to 0.90
Brick 0.90 Rubber 0.95
arbon 0.85 Wood 0.90
Sludge 0.94 Textile 0.94
Frozen Food 0.90 Lead 0.50
Hot Food 0.93 Marble 0.94
Ice 0.98 loth (black) 0.98
Snow 0.90 Sand 0.90
Human Skin 0.98 Water 0.93
12

39
NOTES
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40
Specifications subject to change without notice
©2015 GENERAL TOOLS & INSTR MENTS
NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.
MAN# IRT850K
5/26/15
General Tools & Instruments
GeneralToolsNYC
99 Washington Street
Melrose, MA 02176
Phone [phone]
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com