What is humidity? Differences between relative humidity, absolute humidity, and dew point temperature, and methods for managing humidity.

Humidity is an indicator of how much water vapor is contained in the air. The "humidity of ○%" often used in weather forecasts and indoor environment measurements usually refers to relative humidity.

However, humidity is not simply determined by whether there is a lot or a little water vapor. Air can hold more water vapor at higher temperatures and less at lower temperatures. Therefore, to properly understand humidity, it is necessary to consider not only the amount water vapor but also its relationship with temperature.

There isn't just one reason why humidity levels rise. A common cause is the increase in water vapor in the air due to rain or the rainy season. Indoors, drying laundry indoors, using humidification, cooking, and insufficient ventilation can also contribute to increased humidity.

Furthermore, relative humidity can increase as the temperature drops. Even if the amount of water vapor in the air doesn't change significantly, the amount of water vapor the air can hold decreases as the temperature drops, so the relative humidity tends to display higher.

• The amount of water vapor in the air increases due to rain and the rainy season.
• Indoor drying, cooking, humidification, and insufficient ventilation all increase indoor humidity.
• A drop in temperature can sometimes increase relative humidity.
• Humidity also varies depending on the building structure and ventilation conditions.

Humidity significantly impacts health and home comfort. High humidity makes it difficult for sweat to evaporate, causing heat to build up in the body and making you feel hotter. When taking precautions against heatstroke in the summer, both temperature and humidity are important.

On the other hand, if the humidity is too low, it can easily lead to dry throat and skin, as well as static electricity. High humidity can also lead to dew condensation, mold, and dust mite growth.

Humidity can be expressed in several ways. In living environments, relative humidity is the most common, but in industrial applications, absolute humidity and dew point temperature are also important in some situations.

While relative humidity is easily understood for HVAC management and general environmental monitoring, it may be more appropriate to check absolute humidity and dew point temperature in drying process, material management, and dew condensation prevention.

In typical households, digital temperature/humidity and hygrometers are commonly used. display are easy to read and are perfectly adequate for everyday indoor humidity control.

On the other hand, in factories and research facilities, equipment selection must be tailored to the measurement target and environmental conditions. For example, for air conditioning ducts, constant temperature and humidity chambers, drying equipment, and storage facilities, temperature range, responsiveness, output signal, durability, and maintainability must also be considered.

It's also important to note that humidity measurements are easily affected by installation conditions. Direct sunlight, heat sources, wind exposure, placement near walls, dew condensation, and sensor contamination can all cause errors.

Humidity is crucial in industrial settings not for comfort, but because it directly impacts quality, repeatability, and safety. Changes in humidity conditions can lead to moisture absorption and drying of materials, dimensional changes, static electricity, corrosion, and dew condensation, affecting product quality and process stability.

While humidity control in living environments is primarily focused on "comfort," in industrial applications, the key is "how to connect measurement values to quality assurance and process control."

Factories, research facilities, and environmental testing

Humidity control is necessary for stabilizing process conditions, repeatability test environments, and equipment maintenance. Precision in humidity control is particularly important in drying process, painting, environmental testing, and electronic component manufacturing.

Warehouse/storage environment

To prevent dew condensation, mold, deterioration of packaging materials, and moisture absorption of products, temperature/humidity control is crucial during long-term storage. It is also effective to understand not only the stability of the storage environment but also its fluctuation history.

Pharmaceuticals, reagents, and medical supplies

Because deviations from storage conditions can affect quality and audits, continuous monitoring and record-keeping are crucial. Measurement, as well as record-keeping accuracy and reliability, must be considered.

Food, raw materials, and electronic components

High humidity can lead to mold growth and quality deterioration, while low humidity can cause problems with dryness and static electricity. Appropriate management conditions vary depending on characteristic of the materials and products.

Even if properly managed within a warehouse, temperature/humidity conditions can fluctuate during transportation. In truck transport, the cargo compartment environment is particularly susceptible to changes due to factors such as outside temperature, stopping, door opening and closing, and differences in loading conditions.

In particular, deviations from conditions during transportation can pose a quality risk for products such as pharmaceuticals, precision instruments, electronic components, and food. Therefore, it is important to monitor and record not only storage conditions but also transportation conditions.

Chino's HN-C series temperature/humidity employ polymer capacitive humidity sensors and are indicated for use in air conditioning ducts, constant temperature and humidity chambers, food fermentation rooms, and environmental testing rooms. When measuring humidity, it is important to check not only specifications but also the installation environment and dew condensation conditions.

Because hygrometers are affected by the environment in which they are used and by changes over time, display values may drift over time. Regular calibration is important in environments where quality control, research and development, compliance with standards, and audits are required.

Calibration involves verifying the reliability of measured values by comparing them to a standard instrument. Furthermore, in situations where traceability to national standards is required, a verifiable calibration system is crucial, rather than mere inspection.

Chino's on-site calibration service handles the inspection and calibration of measuring instruments such as temperature and humidity sensors. Before implementation, it would be helpful to organize information about the measurement targets, installation environment, and required calibration points to facilitate the consultation process.

Humidity control equipment isn't simply about measuring humidity. The appropriate equipment varies depending on what you're managing, the installation location, the required accuracy, the temperature range, the risk dew condensation, and the need for recording and monitoring.

• Do you want to measure relative humidity, absolute humidity, or dew point temperature?
• Where should we take the measurement? (Indoors, inside ducts, inside tanks, inside storage rooms, etc.)
• Is room temperature or high temperature, or is the temperature fluctuating significantly?
• Is display sufficient, or is recording and monitoring also necessary?
• How should we consider maintainability, such as periodic calibration and sensor replacement?

Chino supports on-site humidity management through measurement and control equipment, sensors, recorders, monitoring systems, and calibration services, including temperature/humidity and hygrometers.

In factories and research facilities, temperature/humidity control can be considered as a continuous process, including on-site measurement using thermometers and hygrometers; recording and monitoring in warehouses and storage environments; visualization using wireless devices in transportation and mobile equipment management; and calibration and traceability in quality assurance settings.

In monitoring transportation and storage, combining wireless devices and data logging equipment according to the application makes it easier to understand the conditions without having to go to the site. Thinking of temperature/humidity management not just as "introducing measuring instruments" but as "a system for maintaining quality" leads to more practical improvements.