How to Set Emissivity in Infrared Thermometer: Tips and Tricks for Accuracy

Infrared thermometers are powerful tools for measuring temperature remotely, but achieving accurate readings requires understanding and adjusting a crucial setting: emissivity. This blog post will guide you through the intricacies of how to set emissivity in infrared thermometers, ensuring you get reliable temperature measurements every time.

Understanding Emissivity: The Key to Accurate Temperature Readings

Emissivity is a material property that describes how efficiently an object emits infrared radiation. It ranges from 0 to 1, with 1 representing a perfect blackbody that absorbs and emits all radiation. Most materials fall somewhere between these extremes, meaning they emit less than a perfect blackbody.
Think of it like this: a black shirt absorbs more sunlight than a white shirt. Similarly, a black surface emits more infrared radiation than a shiny surface.

Why Emissivity Matters

Infrared thermometers measure temperature by detecting the infrared radiation emitted by an object. The instrument assumes the object is a perfect blackbody (emissivity = 1). However, most materials have emissivity values less than 1. If you don’t adjust the emissivity setting on your infrared thermometer to match the material you’re measuring, your readings will be inaccurate.
Imagine trying to measure the temperature of a polished metal surface. Since metal is highly reflective, it has a low emissivity. If you don’t adjust the emissivity setting, your thermometer will overestimate the temperature because it’s assuming the metal is emitting more radiation than it actually is.

How to Determine Emissivity

Determining the correct emissivity for your material is crucial. Here are some ways to find it:

• Consult a reference table: Many manufacturers provide tables listing the emissivity values of common materials.
• Use a specialized emissivity meter: These devices measure the emissivity of a material directly.
• Refer to the material’s datasheet: Some materials have datasheets that specify their emissivity.
• Experiment: If you can’t find the emissivity value for your material, you can experiment by comparing the readings from your infrared thermometer to a contact thermometer. Adjust the emissivity setting until you get similar readings from both thermometers.

Setting Emissivity on Your Infrared Thermometer

Most infrared thermometers have an emissivity setting that you can adjust. The process varies depending on the model, but typically involves the following steps:
1. Locate the emissivity setting: This is usually a button or a menu option on the thermometer.
2. Select the appropriate emissivity value: Using the methods described above, find the emissivity value for the material you’re measuring.
3. Enter the emissivity value: You may need to use the arrow keys or a dial to adjust the emissivity setting.

Tips for Accurate Emissivity Adjustment

• Consider surface conditions: The emissivity of a material can be affected by factors such as surface roughness, oxidation, and coatings. If the surface is not clean or smooth, you may need to adjust the emissivity accordingly.
• Use the average emissivity value: If you’re unsure about the exact emissivity value, it’s best to use the average value for the material.
• Calibrate your thermometer: Regularly calibrating your infrared thermometer ensures accurate readings.

Common Emissivity Values for Different Materials

Here are some common emissivity values for different materials:

• Metals: 0.1 to 0.3
• Paints: 0.8 to 0.95
• Plastics: 0.8 to 0.95
• Wood: 0.9 to 0.95
• Skin: 0.98
• Water: 0.96

Beyond Emissivity: Other Factors Affecting Accuracy

While emissivity is a critical factor, other factors can also affect the accuracy of infrared thermometer readings. These include:

• Distance: The distance between the thermometer and the target affects the accuracy of the reading. Make sure to follow the manufacturer’s recommended distance guidelines.
• Angle: The angle between the thermometer and the target also affects accuracy. Aim the thermometer perpendicular to the target for the most accurate readings.
• Ambient temperature: The ambient temperature can affect the accuracy of the reading, especially when measuring high or low temperatures.
• Reflected radiation: Reflected radiation from nearby objects can also affect the accuracy of the reading. Try to minimize reflected radiation by shielding the target from other heat sources.

The Importance of Accuracy: Ensuring Reliable Temperature Measurements

Mastering the art of setting emissivity in infrared thermometers is crucial for accurate temperature measurements. By understanding emissivity and following the tips outlined above, you can ensure your infrared thermometer provides reliable and accurate readings, helping you make informed decisions in various applications.

What You Need to Know

1. What happens if I don’t set the correct emissivity?
If you don’t set the correct emissivity, your infrared thermometer will provide inaccurate temperature readings. This can lead to errors in your measurements and potentially incorrect decisions.
2. Can I use the same emissivity setting for all materials?
No, different materials have different emissivity values. You need to adjust the emissivity setting on your infrared thermometer to match the material you’re measuring.
3. How often should I calibrate my infrared thermometer?
The frequency of calibration depends on the specific model and the environment in which it’s used. However, it’s generally recommended to calibrate your thermometer at least once a year or more often if it’s used frequently or in harsh environments.
4. Can I use an infrared thermometer to measure the temperature of a human body?
Yes, infrared thermometers can be used to measure body temperature. However, it’s important to note that the accuracy of these readings can be affected by factors such as ambient temperature, distance, and the presence of sweat or makeup.
5. What are some common applications of infrared thermometers?
Infrared thermometers have a wide range of applications, including:

• Industrial applications: Measuring the temperature of machinery, furnaces, and other equipment
• Medical applications: Measuring body temperature, monitoring patients, and conducting medical research
• Food safety: Measuring the temperature of food products to ensure safety
• Building inspection: Identifying heat loss and energy efficiency issues