How to Measure Humidity Levels in Industrial Environments?
Measuring humidity levels in industrial environments is preferred by manufacturers for precise production processes and product quality. Incorrect humidity levels in production areas can cause product deterioration, equipment damage, and decreased energy efficiency. Therefore, selecting the right measurement devices, proper positioning, and regular calibration are important for businesses in terms of creating sustainable measurement precision and establishing historical data templates. This article aims to provide brief information about the technical details of humidity measurement devices, their proper use, and calibration.
What is Humidity Level and Why Should It Be Measured?
Humidity level refers to the amount of water vapor in the air and is defined by measurements such as relative humidity (%), absolute humidity (g/m³), and dew point. Controlling these values is critically important especially in sectors such as food, pharmaceutical, electronics, and chemicals. For example, mold formation is observed in food products in environments with high relative humidity, while low humidity levels can lead to static electricity buildup in electronic equipment. Absolute humidity and dew point values are important for monitoring thermodynamic processes in the production environment and effectively managing HVAC equipment.
Industrial Humidity Measurement Devices
Measurement devices used in industrial humidity control offer wide measurement ranges and high precision. Users working in industrial processes can make selections among these devices according to their precision and measurement range requirements. Below, devices with different types and features are briefly listed.
1. Hygrometers
Precision Range: ±5%RH (for relative humidity)
Measurement Range: 0% - 100% relative humidity
Applications: Generally used in storage and production areas.
Positioning: Placed at the center of the relevant space or in areas where humidity variation is highest to monitor the humidity level of production lines or storage conditions.
2. Dew Point Sensors
Precision Range: ±0.2°C - ±0.5°C
Measurement Range: -80°C to +20°C dew point
Applications: Used for programming with dew point in HVAC and drying processes.
Positioning: Installed at the outlet of air dryers or in areas requiring precise humidity control.
3. Absolute Humidity Sensors
Precision Range: ±2-3 g/m³
Measurement Range: 0 - 30 g/m³
Applications: Used for precise measurement of water vapor content in the air in chemical production and pharmaceutical sectors.
Positioning: Placed at entry and exit points of the production area for humidity level monitoring. Since absolute humidity sensors are expensive, absolute humidity level is generally calculated and displayed through relative humidity and temperature.
4. Relative Humidity Sensors
Precision Range: ±0.8%RH
Measurement Range: 0% - 100% relative humidity
Applications: Used in HVAC systems and humidity control devices.
Positioning: Placed at points where airflow is most intense within the system or integrated into the return ventilation duct from the area to be conditioned.
Proper Positioning of Humidity Measurement Devices
Incorrect placement of humidity measurement devices can cause inaccurate data collection, inefficient operation of HVAC equipment directed by the devices, and uncontrolled increases in energy costs. Therefore, devices should be positioned considering the following criteria:
1. Within the Production Area: Should be placed in areas where humidity variation is highest. Devices should be located at the beginning and end points of production lines.
2. In Ventilation Systems: Humidity sensors should be placed at air entry and exit points. In HVAC systems, sensors should be mounted parallel to the airflow for proper air flow measurement. Elbows or turbulence lines should not be selected for sensor positioning; sensors should be positioned on straight lines. When positioning on ducts, placing them away from surrounding steam, water, and hot air lines minimizes the possibility of erroneous measurements caused by external factors.
3. In Storage Areas: In storage areas where humidity levels are critical, devices should be placed at the center and corners of the area. The number of sensors should be increased proportionally to the size of the storage area, and the automation operating scenario should be updated accordingly. Dew point sensors can be positioned near the shelves where products are stored, or start/stop commands can be given to the device through automation based on the average from sensors in the space.
The Importance of Calibration
Humidity measurement devices need to be regularly calibrated to ensure proper operation. Calibration directly affects the precision and accuracy of devices. Calibration of industrial devices is performed as follows:
Relative Humidity Calibration: Performed by testing the device at different relative humidity levels in a controlled environment.
Dew Point Calibration: Accuracy control is performed by comparison with a reference dew point device.
Absolute Humidity Sensor Calibration: Measurement precision is checked using known water vapor concentrations.
Calibration Intervals: It is recommended that devices be calibrated at least once a year in industrial use.
Accurately measuring humidity levels in industrial environments is a matter that requires attention for quality production and energy savings. Devices such as hygrometers, dew point sensors, and absolute humidity sensors play an effective role in properly directing ventilation equipment in production processes with their wide measurement ranges and high precision. Proper positioning, calibration, and use of sensors both increases efficiency and reduces sustainable HVAC costs. For more information about humidity control and measurement devices, contact the NKT - Humidity Control Technologies expert team.
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