Major tech MT691 User manual

MT691
Infrared Thermometer with
Dual Laser
INSTRUCTION MANUAL

Index
Page no
3

1. Introduction
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Ÿ Thank you for purchasing the MT691 IR Thermometer. This
instrument is capable of non-contact (Infrared) temperature
measurements at the touch of a button. The built-in laser pointer
increases target accuracy while the backlight LCD and handy
push-buttons combine for convenient, ergonomic operation.
Ÿ The MT691 Non-contact Infrared Thermometers can be used to
measure the temperature of objects surface that is improper to be
measured by traditional (Contact) thermometer (Such as moving
object, the surface with electricity current or the objects which are
not possible to be touched).
Ÿ Proper use and care of this meter will provide years of reliable
service.
Ÿ Rapid detection function
Ÿ Precise non-contact measurements
Ÿ Dual laser sighting
Ÿ Unique flat surface, modern housing design
Ÿ IP54 rated for dust/waterproof
Ÿ 2 meter drop tested
Ÿ Automatic Data Hold
Ÿ Emissivity Digitally adjustable from 0.10 to 1.0
Ÿ MAX, MIN, AVG, DIF temperature displays
Ÿ Backlight LCD display
Ÿ Automatic selection range and Display Resolution
0.1°C (0.1°F)
Ÿ Set high and low alarms
2. Features

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3. Wide Range Application
Food preparation. Safety and Fire inspectors. Plastic molding,
Asphalt. Marine and Screen printing, measure ink and Dryer
temperature, HVAC/R, Electrical, Diesel and, Fleet maintenance.
4. Safety
Ÿ Use extreme caution when the laser beam is turned on.
• Do not let the beam enter your eye, another person’s eye or the
eye of an animal.
• Be careful not to let the beam on a reflective surface strike your
eye.
• Do not allow the laser light beam impinge on any gas which can
explode.
5. Distance & Spot Size
Ÿ As the distance (D) from the object increases, the spot size (S) of
the area measured by the unit becomes larger. The relationship
between distance and spot size for each unit is listed below. The
focal point for each unit is 914mm (36"). The spot sizes indicate
90% encircled energy.

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6. Specifications
Note: Field of View: Make sure that the target is larger than the unit’s spot size. The smaller
the target, the closer you should be to it. When accuracy is critical, make sure the target is at
least twice as large as the spot size.
Temperature Range -50 to 650°C (-58°F ~ 1202°F)
D:S 12:1
Display Resolution 0.1 °C (0.1 °F) <1000
1°F >1000
Accuracy for targets
Assumes ambient operating temperature of 23 to 25°C (73 to 77°F)
-50 - 20°C (-58°F - 68°F) ±3.5°C (6.3°F)
20°C -300°C (68°F-572°F) ±1.0% ±1.0°C (1.8°F)
300°C -650°C (572°F -1202°F) ±1.5%
Repeatability -50-20°C (-31-68°F): ±1.8°C (3.2°F)
20-650°C (68-1202°F): ±0.5% or ±0.5°C (0.9°F)
Response Time 150ms
Spectral Response 8~14um
Emissivity Digitally adjustable from 0.10 to 1.0
Over Range Indication LCD will show “____ ”
Polarity Automatic (no indication for positive polarity);
Minus (-)sign for negative polarity
Diode Laser Output <1 mW, Wavelength 630~670nm, Class 2 laser product
Operating Temp. 0 to 50°C (32 to 122°F)
Storage Temp. -10 to 60°C (14 to 140°F)
Relative Humidity 10%-90%RH operating, <80%RH storage
Power Supply 2x1 .5V AAA batteries
Safety "CE" Comply with EMC

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7. Front Panel Description
1 - DIR sensor
2 - LCD Display
3 - up button
4 - down button
5 - mode button
6 - Measurement Trigger
7 - Handle Grip
8 - Battery Cover
7-1. Indicator
1 - Scan symbol
2 - Data hold
3 - Laser "on" symbols
4 - High alarm and low alarm symbol
5 - °C/°F symbol
6 - Low power symbols
7 - Emissivity symbol
8 - Emissivity value
9 - Temperature values for the MAX/ MIN/DIF/AVG
10 - Symbols for MAX/MIN/DIF/AVG
11 - Current temperature value

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7-2. Buttons
1 - Up button (for EMS, HAL, LAL)
2 - Down button (for EMS, HAL, LAL)
3 - MODE button (for cycling through
the mode loop)
1 - Press the up and down keys to adjust the Emissivity.
2 - Press the up key to turn the laser on or off and the down key to
turn the backlight on or off.
3 - Press the MODE button to change MAX/MIN/DIF/AVG
4 - To set values for the High Alarm (HAL), Low Alarm (LAL) and
Emissivity (EMS), press and hold the MODE button until the
appropriate code appears in the display, press the UP and down
buttons to adjust the desired values.)
8. Functional Design

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Pressing the mode button also allows you to
access the set state, Emissivity(EMS), °C/F, HAL
on/off, HAL adjustment, LAL on/off, LAL
adjustment. Each time you press the set key you
advance through the mode cycle.
The diagram shows the sequence of functions in
the mode cycle.
EMS adjustment. The Emissivity(EMS) digitally
adjustable from 0.10 to 1.0.
9. MODE Button Function
°C/F.
Press the up/down button to change the temperature unit
(°C or °F)
HAL/LAL on/off. Press the up button or down button to turn on or
off. Press the Measurement Trigger to confirm the High/Low alarm
mode. HAL/LAL adjustment, the High/Low alarm adjustable from
-50 to 650°C (-58°F- 1202°F).
MAX MIN DIF AVG indicates the MAX MIN DIF AVG which is
recorded by pressing and releasing the "ON/OFF" button each
time.
MAX MIN DIF AVG display
MAX = maximum .Maximum value of measurement.
MIN = minimum. Minimum value of measurement.
DIF = difference. Difference value of measurement.
AVG = average. Average value of measurement.

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10. Measurement Operation
1. Hold the meter by its Handle Grip and point it toward the surface needing
to be measured.
2. Pull and hold the Trigger to turn the meter on and begin testing. The
display will light up if the battery is good. Replace the battery if the display
does not light up.
3. Release the Trigger and the HOLD display icon will appear on the LCD
indicating that the reading is being held. In HOLD status, press the UP
button to turn on or off the laser. And press the DOWN button to turn on
or off the backlight.
4. The meter will automatically power down after approximately 10 seconds
after the trigger is released. (Unless the unit is locked on).
Note: Measurement considerations
• Holding the meter by its handle, point the IR Sensor toward the object
whose temperature is to be measured. The meter automatically
compensates for temperature deviations from ambient temperature. Keep
in mind that it will take up to 30 minutes to adjust to wide ambient
temperatures to be measured followed by high temperature
measurements, some time (several minutes) is required after the low (and
before the high) temperature measurements are made.
• This is a result of the cooling process, which must take place for the IR
sensor.
11. Battery Replacement
1. If the battery power is not sufficient the
""
LCD will display replace with
2xAAAbatteries.
2. Open the battery cover to replace the
batteries in the instrument. Close the
cover to carry on using the instrument.

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12. Notes
Ÿ How it Works
Infrared thermometers measure the surface temperature of an object.
The unit's optics sense emitted, reflected, and transmitted energy,
which is collected and focused onto a detector. The unit's electronics
translate the information into a temperature reading, which is displayed
on the unit. In units with a laser, the laser is used for aiming purposes
only.
Ÿ Field of View
Make sure that the target is larger than the unit’s spot size. The smaller
the target, the closer you should be to it. When accuracy is critical,
make sure the target is at least twice as large as the spot size.
Ÿ Distance & Spot Size
As the distance (D) from the object increases, the spot size (S) of the
area measured by the unit becomes larger.
Ÿ Locating a hot Spot
To find a hot spot aim the thermometer outside the area of interest.
then scan across with an up and down motion until you locate hot spot.
Ÿ Reminders
1. Not recommended for use in measuring shinny or polished metal
surfaces (stainless steel, aluminum, etc.). See Emissivity.
2. The unit cannot measure through transparent surfaces such as
glass. It will measure the surface temperature of the glass instead.
3. Steam, dust, smoke, etc., can prevent accurate measurement by
obstructing the unit's optics.
Ÿ Emissivity
Emissivity is a term used to describe the energy-emitting
characteristics of materials. Most (90% of typical applications) organic
materials and painted or oxidized surfaces have an emissivity of 0.95
(pre-set in the unit). Inaccurate readings will result from measuring
shinny or polished metal surfaces.
To compensate, cover the surface to be measured with masking tape
or flat black paint. Allow time for the tape to reach the same
temperature as the material underneath it. Measure the temperature of
the tape or painted surface.

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13. Emissivity Values
Substance Thermal Emissivity
Asphalt 0.90 to 0.98
Concrete 0.94
Cement 0.96
Sand 0.90
Earth 0.92 to 0.96
Water 0.92 to 0.96
Ice 0.96 to 0.98
Snow 0.83
Glass 0.90 to 0.95
Ceramic 0.90 to 0.94
Marble 0.94
Plaster 0.80 to 0. 90
Mortar 0.89 to 0. 91
Brick 0.93 to 0.96
Cloth (black) 0.98
Human skin 0.98
Lather 0.75 to 0.80
Charcoal (powder) 0.96
Lacquer 0.80 to 0. 95
Lacquer (matt) 0.97
Rubber (black) 0.94
Plastic 0.85 to 0. 95
Timber 0.90
Paper 0.70 to 0. 94
Chromium oxides 0.81
Copper oxides 0.78
Iron oxides 0.78 to 0.82
Textiles 0.90

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14. Maintenance
Ÿ Repairs or service are not covered in this manual and should only
be carried out by a qualified technician.
• Periodically, wipe the body with a dry cloth. Do not use abrasives
or solvents on this instrument.
• For service, use only manufacturer's specified parts.

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