Extech 1400F Infrared Thermometer With Alarm (42540)

In stock
Measures up to 1400F (760C). With a field of view of 16:1 and laser for accurate temperature measurement. With an alarm to alert you if the temp exceeds the set high and low temperatures.

Extech Infrared Thermometer With Alarm 1400F (42540)


  • Displays non-contact temperature readings up to 1400F (760C).
  • Fast and accurate measurements with 16:1 field of view
  • Large LCD display with bright backlight
  • MAX/MIN/AVG/DIF feature displays highest, lowest, average, and MAX minus Min values
  • Built-in laser pointer improves aim and measurement accuracy
  • Adjustable emissivity increases measurement accuracy for different surfaces
  • Adjustable High/Low set points with audible alarm alerts user when temperature exceeds the programmed set points
  • High resolution of 0.1º up to 199.9º
  • Complete with 9V battery and carrying case
  • Automatic Data Hold
  • Auto Power Off

The Extech Model 42540 IR Thermometer measures and displays non-contact temperature readings up to 1400F (760C). The laser pointer ensures accurate targeting and temperature measurement. The adjustable high/low set points with an audible alarm will alert the user when the temperature exceeds the programmed set points. The adjustable emissivity feature allows the IR thermometer to measure the temperature of virtually any surface. Proper use and care of this meter will provide years of reliable service.

The meter has a distance to target ratio of 16:1. The spot size at this distance has a 1” diameter. The closer to the meter the smaller spot size for measurement you will have. This meter has an automatic data hold as well as an automatic power off feature. Complete with 9V battery and carrying case.

Measuring Leaf Temperature

laser_engineInfrared Thermometers are useful tools for so many applications where the surface temperature of something is important. One of the most important uses of an IR Thermometer in agriculture is to measure the temperature of your leaves. Measuring the difference between leaf temperature and ambient air temperature has been discovered to be one of the best indications of plant stress from heat, light and especially lack of water. High temperature differentials between leaf temperature and ambient air temperature has been found to lead to reduced yields so monitoring this is extremely important.

Distance : Spot Ratio

The infrared thermometers have a ratio such as 16:1  which is the distance to spot ratio. This means that the beam diameter cast on the leaf will be 1/16th of the distance from the sensor to the object. For example if you stood at 16 inches away from the leaf, the beam of light cast on the leaf would measure 1 inch in diameter, in other words the closer you are to the leaf the more concentrated the area will be that you measure. The higher the distance:spot ratio, the better quality the thermometer and you can also take accurate measurements from further away from the target.


  • IR Range -58 to 1400°F (-50 to 760°C)
  • Repeatability ±0.5% or 1.8°F/1°C
  • Basic Accuracy ±2%rdg or 4ºF (2°C) 932°F (500°C)
  • Max resolution 0.1°F/°C
  • Power 9V Battery
  • Emissivity 0.10 to 1.00 Adjustable
  • Field of View (Distance to Target) 16:1
  • Dimensions 3.9x2.2x9" (100x56x230mm)
  • 3 Year Warranty

Unit ship weight: 2 Lbs

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