How to Calibrate a Thermohygrometer with a Humidity and Temperature Chamber

Learn Something About Thermohygrometer

Thermohygrometer is composed of a temperature measuring element and a moisture sensitive element, which can directly display the temperature and relative humidity measurement value.

It is widely used in indoor environment temperature and humidity measurement in laboratories, warehouses, factories and other fields.

Why do Thermohygrometers Need to be Calibrated Regularly?

Temperature and humidity equipment is an instrument used to measure the temperature and humidity in the environment. Regular calibration of temperature and humidity equipment can ensure the accuracy and reliability of its measurement results. During the use of temperature and humidity equipment, due to long-term use, transportation, environmental conditions and other reasons, the sensors in the instrument may drift or shift, resulting in inaccurate measurement results. Additionally, sensor performance can change over time, which can lead to skewed readings from temperature and humidity equipment. Therefore, regular calibration is very necessary.

Calibration can be performed by comparing the temperature and humidity equipment to a standard instrument of known temperature and humidity. The calibration process corrects for sensor drift or offset in the device so that its readings comply with standards, thereby ensuring accurate and reliable measurements. Generally speaking, the calibration cycle of temperature and humidity equipment should be determined according to factors such as frequency of use and environmental conditions, but it is generally recommended to perform calibration at least once a year.

How to Calibrate a Thermohygrometer?

The standard way for a Thermohygrometer calibration is to use a Temperature and Humidity test chamber or a humidity generator, this is usually performed in a lab. The humidity generator can be varied to different range of humidity and temperature.

● Calibration Conditions

Ambient temperature: (15~30)°C;

Ambient humidity: 85%RH.

There should be no strong vibration, strong electromagnetic field or other interference around the instrument and equipment during calibration.

● Equipment-Temperature and Humidity Test Chamber

Temperature: -40 ~+50°C

Humidity: 20~95%RH

Temperature uniformity: 0.3°C, temperature fluctuation: ±0.2°C

Humidity uniformity: 1.0%RH, humidity fluctuation: ±0.8%RH

Temperature Range	A : -20°C ～ +150°C B : -40°C ～ +150 °C C: -70°C ～ +150 °C
Temperature Fluctuation	± 0.5 °C
Temperature Deviation	± 2.0 °C
Humidity Range	20% ~ 98% RH
Humidity Deviation	± 2.5% RH

● Visual Inspection, Calibration Items and Calibration Methods

Calibration items can be selected according to the intended use of the instrument being calibrated.

Visual Inspection

The shape and structure of the thermohygrometer shall be intact, and the model and number shall be complete. There should be no visible dents, cracks and deformation and other phenomena, the sensor should be well packaged.

After the thermohygrometer is powered on, the digital display should be clear, no overlapping words, uniform brightness, and there should be no unbright and missing strokes or none measurement units and other phenomena, the status display should be clear and correct.

Calibration Equipment Installation

Place the calibrated thermohygrometer in the Temperature and Humidity test chamber.

Thermohygrometer indication correction value.

Temperature calibration points: 15°C, 20°C, 30°C. When calibrating, start readings when the temperature equilibrates 30 minutes later. First read the data, then read the instrument under test, and repeat the reading after an interval of 5 minutes.

Humidity calibration is carried out in order from low humidity to high humidity, and the calibration points are: 20%RH, 40%RH, 60%RH,80%RH. The temperature value is set to 20°C during calibration. When the temperature is equilibrated, each humidity calibration point stabilizes at the set value. Start reading after 30 minutes, read the data first, then read the instrument under test, and repeat the reading after 5 minutes interval. Then do the next calibration point, until all calibration points are tested.

Calculate the average of the displayed values of temperature and humidity of the standard and the calibrated thermohygrometer for each calibration point.

● Resumption Interval

It is recommended that the recalibration interval of the digital temperature and humidity meter be 1 year. The sending unit can also be independent according to the actual usage.

LIB Temperature and Humidity Test Chambers

Founded in 2009, LIB industry is a manufacturer and supplier of environmental test chambers, and now has its own agents and service centers in many countries around the world. LIB's products are popular all over the world because of our high quality and powerful performance.

If you need a Temperature and Humidity test chambers to calibrate your thermohygrometer, contact us now.