There are various conditions we need to know on-site, such as temperature, humidity, and moisture. The basic idea of sensing is to detect these conditions in some way and convert them into information that can be used for comparison, recording, and decision-making.

The term "sensing" is used very broadly and includes a wide range of objects, not just temperature and humidity, but also pressure, flow rate, position, vibration, and more. Here, we will look at what "measuring" actually entails, focusing on industrial measurement, which is the focus of CHINO.

What is the difference between a sensor and sensing?

A sensor is an element or device used to capture the state or changes of an object.

Sensing refers to a series of actions and technologies that use sensors and other devices to capture the state and changes of an object and acquire necessary information.

For example, a thermocouple is a typical temperature sensor used to measure temperature.

However, the purpose is not simply to install thermocouples. There are objectives such as "I want to know the temperature of the product" or "I want to check the temperature inside the furnace," and thermocouples are used as a means to achieve these objectives.

In other words, a sensor is one element for performing sensing, and sensing includes the concept of using that sensor to obtain the necessary information.

How is this different from measurement and testing?

The terms "sensing," "measurement," and "analysis" are actually used interchangeably. Therefore, they cannot be clearly distinguished in all situations.

On this page, we will treat sensing as a broad entry point: "capturing the state and changes of an object and acquiring necessary information."

The actual methods for measuring temperature and how to handle the measured values are explained in detail in "What is Temperature Measurement?".

• What is temperature measurement? Differences from other measurements, how it works, and how to measure temperature correctly.

When considering sensing, the first thing to confirm is not "which sensor to use," but "why measure."

To know the condition as information that can be compared, recorded, and judged.

Humans can judge the state of their surroundings to some extent through sensations such as "hot," "cold," "damp," and "dry."

However, relying solely on intuition makes it difficult to accurately compare conditions or verify them later.

For example, information like "It's a little hotter than yesterday" is less helpful than information like "Yesterday it was 100°C, today it's 110°C" because it makes it easier to handle the difference in conditions.

By measuring, we can compare and record the state of an object, compare it against a standard, detect changes, and identify abnormalities.

In other words, measuring means understanding the conditions on-site as information that can be used for judgment and action.

Before considering "what to measure," think about "what you want to know."

For example, let's say you're measuring the temperature in an industrial furnace. In this case, is "temperature" really what you want to know?

In reality, the temperature may be measured to determine whether "the product is being heated properly," "whether the heat treatment is being carried out under the specified conditions," and "whether there is any abnormal temperature rise."

The same applies when measuring moisture during the drying process. moisture content itself isn't the primary factor; rather, it's moisture to determine whether the product is sufficiently dried, ready for the next process, and whether the product quality meets the standards.

If the objective changes, the necessary sensing also changes.

Even when measuring the same temperature, the required conditions vary depending on the purpose. Whether you want to detect abnormalities quickly, use them for product quality control, or control equipment, the required accuracy, responsiveness, measurement location, and frequency will vary.

Therefore, it is important to consider not only "what temperature to measure," but also "why you want to know that condition" before deciding on a measurement method.

Thermocouples utilize thermoelectric power, which is related to temperature.

Thermocouples determine temperature by utilizing the relationship between the thermoelectric voltage generated in a circuit of different metals and the temperature.

In other words, temperature is treated as information through a conversion process that goes from "temperature → thermoelectric power → electrical signal → temperature information".

For a detailed explanation of the principles and types of thermocouples, please see "What are thermocouples?".

• What is a thermocouple? A temperature measurement manufacturer explains its principle, types, and how to choose one in an easy-to-understand way.

radiation thermometer utilize infrared radiation emitted from objects.

There isn't just one way to measure temperature. radiation thermometer detect electromagnetic waves emitted from an object and determine the temperature from that information.

It's clear that they're using a different phenomenon than thermocouples to obtain the same "temperature" information.

• What is infrared measurement? A clear explanation of how it measures temperature, moisture, constituent, and thickness.
• A Guide to Avoiding radiation thermometer | Principles, emissivity, D:S Ratio, and Selection Methods for Non-Contact Temperature Measurement

Infrared moisture meters utilize absorption of infrared radiation related to moisture.

Regarding moisture, instead of directly reading moisture itself, there are methods that utilize the changes in infrared absorption caused by moisture.

This method utilizes the following relationship: "moisture → Change in infrared absorption → Optical information → moisture information".

For a detailed explanation of the principles and calibration curve, please see "What is an infrared moisture meter?".

• What is an infrared moisture meter? An explanation of its non-contact method of measuring moisture, including its principle, calibration curve, and measurement points.

The table above shows typical examples. The applicable principles and methods will vary depending on the object being measured and the application.

I want to know the temperature.

Temperature can be measured using methods such as thermocouples and resistance thermometer, as well as non-contact methods that utilize infrared radiation.

The most suitable method depends not only on the temperature range, but also on the object being measured, the required accuracy, responsiveness, and installation conditions.

• What is temperature? Fundamentals of temperature measurement, temperature control, and temperature sensors, and their industrial applications.
• Temperature Sensor Guide | Differences between Thermocouples and resistance thermometer and Selection Points (FAQ)
• What is infrared measurement? A clear explanation of how it measures temperature, moisture, constituent, and thickness.

I want to know the humidity and dew point.

To understand the state of water vapor in air or gases, indicators such as humidity and dew point are used.

Relative humidity, absolute humidity, and dew point each represent different things. It is important to clarify what you want to know before considering the appropriate indicator and measurement method.

• What is humidity? A clear explanation of the meaning of 50% humidity, relative humidity, absolute humidity, and dew point.
• What is dew point temperature? A clear explanation of its difference from humidity, its relationship to dew condensation, and how to calculate it.

I want to know about moisture

There isn't just one way to measure moisture content in solids, powders, food products, and raw materials.

Various phenomena can be utilized, such as mass changes due to drying, electrical characteristic, and infrared absorption.

Furthermore, the most suitable method varies depending on whether the measurements are taken in a laboratory or continuously on a manufacturing line.

• moisture What Is It? A Clear Explanation of Moisture Content: Its Meaning, How It Differs from Humidity, and the Basics of Measurement moisture
• What is moisture measurement? A clear explanation of typical measurement methods and how to choose the right one.
• What is moisture measurement in the manufacturing process? A clear explanation of the concepts of online and continuous measurement.

Even for the same thing, there isn't just one way to measure it.

You don't need to start by thinking only about the name of the equipment, such as "This sensor is for temperature" or "This measuring instrument is for moisture."

By considering the target, environment, required accuracy, measurement frequency, and intended use after measurement, a suitable sensing method can be identified.

It is important to consider the object of measurement and the measurement method as separate axes.

Measuring is the starting point for making judgments and taking actions.

The information obtained through sensing can be used for a variety of purposes.

• Record the status
• Visualize the changes
• Monitoring for abnormalities
• control the equipment
• Check the quality
• Analyze data to make improvements.

In IoT and data analysis, the starting point is to acquire data on what is happening with equipment and products.

In other words, sensing is one of the gateways that connects the actual state of things with subsequent decisions and actions.

In temperature control, what happens "after the measurement" is also important.

Simply measuring temperature does not necessarily complete temperature management. Based on the measured information, equipment may be control, abnormalities may be monitored, and records may be made for later review.

Furthermore, it is necessary to maintain the measurement values in a consistently reliable state.

The method of considering measurement, control, monitoring, and calibration as a continuous process is explained in detail in the "Temperature Loop" section.

• Temperature Loop | A Concept of Temperature Management that Connects Measurement, control, Monitoring, and Calibration

Just because the sensor reacted doesn't necessarily mean the measurement was accurate.

For example, with temperature sensors, the mounting location and installation method can affect the measured values.

When using radiation thermometer, it is necessary to consider factors such as emissivity of the object being measured, the measurement distance, the measurement range, and reflections from the surroundings.

In other words, "the sensor detecting some kind of change" and "the state that we really wanted to know about being properly captured" are not the same thing.

It is important to consider factors such as the object to be measured, the measurement method, installation conditions, and the surrounding environment.

To use the measured values with confidence

When using measurements for quality control or equipment control, it is necessary to consider how reliable those values are.

To achieve this, it's necessary to check not only the measurement method, but also the measurement conditions, sensor status, installation method, changes over time, and calibration.

By considering not only "how to measure" but also "how to trust and use those values," it becomes easier to connect sensed information to actual decision-making.

• How to properly install a temperature sensor: Explanation of insertion depth, installation position, and errors due to heat conduction.
• Is your radiation thermometer reading inaccurate? What causes errors, and how can you correct them and check your readings?
• What is calibration? Calibration is a system that compares the value of a measuring instrument to a standard and checks for any differences.

For example, even if you're measuring the temperature during the drying process, what you really want to know isn't the temperature itself, but whether the product is "sufficiently dry."

In that case, checking conditions other than temperature may provide information closer to your objective.

The important thing is not to start by thinking about measuring instruments or sensors, but to start with the objective and then work your way back to measurement.

Six questions to consider when thinking about sensing

1. What do you want to know?
2. Why do we need to know that?
3. What changes in relation to that state?
4. What phenomena can be used to capture this?
5. Under what conditions, with what level of accuracy and speed, is this information necessary?
6. What will you use the information you obtain for?

Sensing is not simply about measuring something with a sensor.

This is the gateway to transforming what you want to know into information that can be used for judgment and action.

When you find yourself wondering, "Why am I measuring this?", going back to this question and thinking about it will help you see the truly necessary measurement methods.