Contact Thermometer vs Non-contact Infrared Thermometer difference

This page compares contact thermometer vs non-contact infrared thermometer and mentions difference between contact thermometer and non-contact infrared thermometer types. It mentions advantages of non-contact Infrared thermometer over contact thermometer type.

Introduction : Temperature measurement is most commonly performed across various industries such as medical, mechanical, civil, manufacturing, quality control, food processing, agriculture etc. Temperature monitoring is essential to monitor quality of perishables, fruits and vegetables after it is produced at source, destination and during transport. This measurement is carried out using various types of contact thermometers.

Moreover, due to pandemic diseases such as COVID-19, it has become very much essential to measure the body temperature often to check whether it is not due to illness or infection. Moreover as the disease is contagious it is mandatory to keep distance of about 6 feet to measure the temperature of the patients. This measurement is carried out using non-contact infrared thermometer.

Contact Thermometer

The thermometer which requires contact with the item whose temperature is to be measured is known as contact thermometer. Based on this, there are different types of thermometers used for temperature measurements of food, liquids, semi-solid, surface, air, human body etc. These contact thermometers usually work as per principles of thermocouple, RTD and thermistor. As these thermometers use external probes they are also known as probe thermometers.

Contact Thermometers

Contact thermometers work based on principle of heat transfer mechanism called "conduction". The figure-1 depicts food thermometer of pocket type and digital thermometer for body temperature measurement due to fever.

Advantages of contact thermometer

Following are the benefits or advantages of contact thermometer.
➨It offers very accurate temperature measurement due to its close surface or body contact.
➨It offers wide temperature measurement range.
➨It offers less measurement response time.
➨It is inexpensive and hence it can be affordable.
➨Due to its contact based functionining it can operate in hazardous and unclean environments.

Non-contact Infrared Thermometer

The thermometer which does not require any surface or body contact is known as non-contact thermometer. It uses infrared sensor for its working operation. It measures reflected emissions of infrared waves from the object under measurement. Infrared rays are invisible and has wavelength greater than visible light.

Non-contact Infrared Thermometer

The figure-2 depicts non-contact infrared thermometer. They are battery powered and are comfortable to hold by hand. They are avaiable to measure the body or surface temperature measurement from a distance. These thermometers provide temperature measurement of patients having fever which helps to know whether fever is high, low or normal.

Advantages of Infrared Thermometer over Contact thermometer

Following points summarize benefits or advantages of Infrared Thermometer over Contact thermometer type.
➨It helps to measure extreme temperatures without any safety issues.
➨It is quick and fast to measure temperature with the pull of trigger button.
➨There is no risk of contamination due to its non-contact functionality.
➨It is light in weight and compact in size.
➨It is used to measure temperature of inaccessible objects or surface parts.

Difference between Contact Thermometer and Non-contact Infrared Thermometer

Following table mentions comparison between contact thermometer and non-contact infrared thermometer types.

Parameters Contact Thermometer Non-contact Infrared Thermometer
Function It requires contact to perform
temperature measurement as
it works based on heat transfer phenomenon.
It does not require contact to
peform temperature measurement
as it uses infrared waves.
Classification Based on sensor type,
they are categorized into
thermocouple, RTD
(Resistance Temperature Detector)
and Thermistor.
Based sensor type and
its principle of working operation
, infrared thermometer
are of two types
viz. active and passive.
Measurement of liquids or
Possible Not possible
Environment It does not require environment
to be clean.
It requires environment to be clean.
Cost Cheaper Expensive
External power or battery Not required Required
Accuracy Very accurate moderate to high accuracy
based on model
Contamination risk YES NO
Measurement time Long Very short
Complexity Complex Simple and easy
Measurement of inaccessible
object or surface
Not feasible Feasible

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