Advantages of Handheld Infrared Thermometer | Disadvantages of Infrared Thermometer

This page covers advantages and disadvantages of Handheld Infrared Thermometer. It mentions benefits or advantages of Infrared Thermometer and drawbacks or disadvantages of Infrared Thermometer. The comparison between contact thermometer and non-contact infrared thermometer are also mentioned.

Normal body temperature of humans range from 36.1oC (97oF ) to 37.2oC (99oF). This body temperature varies based on person's age, time of day and activitity. During fever caused by any infection or illness, the body temperature rises to about 38.4oC (i.e. 100.4oF).

COVID-19 has spread across the world recently. Under this pandemic, in order to protect yourself and to avoid infecting others, it is essential to check body temperature frequently. If high temperature is observed, it is highly recommended to have medicine and take rest.

What is Infrared Thermometer?

Thermometer is a device which measures body temperature. The infrared thermometer uses infrared sensor which emit IR waves to measure the body temperature. Hence it is called non contact thermometer type. Infrared rays are invisible to humans as they have wavelength longer than visible light. The figure depicts one such handheld infrared thermometer.

Handheld Infrared thermometer

Let us understand how infrared thermometer works.
• When user decides to take the temperature measurement, the device needs to be powered ON. Put the batteries in the battery slot if not installed.
• Keep the MODE settings as desired. By default it is fixed to body temperature measurement. The other MODE settings available are used for temperature measurement of body or object surface.
• Set the unit of measurement by pressing "oC/oF button" to either oC or oF.
• Now keep the thermometer at the distance of 2-5 cm from the body or forehead.
• Next measuring switch is pressed and rays are allowed to fall on the body.
• Within seconds the thermometer device displays temperature on its LDC display screen. This is possible as infrared sensor detects the reflected waves from the body and produces voltage accordingly. This voltage range is calibrated for different temperature range for measurement.
• Based on celsius or fahrenheit setting, it displays temperature accordingly.
• Some infrared thermometers display different background colors based on temperature range to indicate various levels of fever (low, high, normal). 32 to 37.3oC indicates green color and it is considered normal temperature range. The range from 37.4 to 38oC indicates low fever (with yellow light) where as range from 38.1 to 39.1oC indicates very high fever (with red light). Some infrared thermometer use buzzer to indicate completion of the measurement.
• One can press the "MEM" button to twice to cycle through previously recorded measurements. User can clear the memory by pressing this "MEM" button for longer duration.

Specifications of Handheld Infrared Thermometer

Following features or specifications are commonly found in infrared thermometer. These are considered for selection of infrared thermometer for your need.
• Temperature measurement unit should be both oC and oF.
• Measurement speed should be as low as possible (typically 1-2 seconds).
• It should have comfortable grip for hand.
• It should be battery powered.
• It should have indication with different colors for normal/high/light fever.
• It should have button (such as "MODE") to set temperature measurement type i.e. body or surface.
• It should have battery indicator to display its status.
• It should have memory to hold previous measurements.
• It should have "auto shut off" feature when user forgets to power OFF the device.

Benefits or advantages of Infrared Thermometer

Following are the benefits or advantages of Handheld Infrared Thermometer:
➨It is simple, comfortable and easy to take temperature measurement.
➨It is very fast technique in comparison to contact based thermometers such as thermocouple, thermistor or RTD. Normally non-contact thermometer gives measurement in seconds (~1-2s).
➨It does not require any body contact to conduct measurement which is very much preferable during pandemic situations such as COVID-19, Flu etc.
➨Most of the infrared thermometer gets automatically switched OFF in order to save the battery when kept ON for long time (~15 seconds).
➨It is very light in weight and compact in size.
➨As it is non-contact type, there is no risk of contamination and no mechanical effect on the surface of the object.
➨Due to its operating principle it can be used to measure inaccessible objects.
➨Its accuracy is comparable with contact thermometer types.
➨It is available at affordable cost.
➨It measures moving objects.

Drawbacks or disadvantages of Infrared Thermometer

Following are the drawbacks or disadvantages of Infrared Thermometer:
➨Infrared waves affect the eyes at high power. It is required to take atmost care while performing measurements. The device should be targetted to forehead or hand or any other parts carefully.
➨It gives accurate measurement when both device and measurement surface is in LOS (Line of Sight). Moreover it supports short range and hence device needs to be closer while taking measurement.
➨It is ideal for body and surface measurements. It can not be used for temperature measurements of liquids or gases. For this application, other types of thermometers are used.
➨The environment should be clean for infrared thermometer to function accurately.
➨Accuracy of measurement varies with different models which are available at different prices from low to very high.

Comparison between contact thermometer and non-contact infrared thermometer

Following table compares contact thermometer vs non-contact thermometer types based on different parameters and mentions comparison between contact and non-contact infrared thermometer.

Contact Thermometer vs Non-contact Infrared Thermometer

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