Calibration Specification of Humidity Sensors

JJF 1076-2001 Humidity sensor calibration specification JJF1076-2001 standard download decompression password: www.bzxz.net
This specification is applicable to the calibration of electrical parameter type relative humidity meters, humidity sensors and humidity transmitters.

1 Scope
JJF 1076—2001
Calibration Specification for Humidity Sensor
This specification applies to the calibration of electrical parameter type relative humidity meters, humidity sensors and humidity transmitters. 2 References
《Humidity Measurement》, Meteorological Press, 1990, 1st edition A Guide to the Measurement of Hurnidity NPL Published 1996 (《Humidity Measurement Guide》 1996 English edition)
3 Overview
Humidity sensor is composed of humidity sensitive elements such as humidity sensitive capacitors, humidity sensitive resistors or humidity sensitive resonators and their conversion circuits, and is a hygrometer that can display relative humidity, or a sensor that can output digital measurable signals such as voltage, current, frequency, etc. Its output signal should be a single-value linear value of the relative humidity (or absolute humidity) in the measured environment. The humidity sensor should be accompanied by technical documents including descriptions of humidity measurement range, output signal range, adjustable parameters (such as zero point, span, etc.), load requirements, working power supply, etc. 4 Metrological characteristics
Accuracy grade of humidity sensor
The accuracy grade of humidity sensor corresponds to the maximum setting value of the correction value of humidity sensor (at a certain temperature). Correction value of humidity sensor
4.3 Temperature coefficient of humidity sensor
Stability of condensation sensor
Response time of humidity sensor
4.6 Hysteresis of humidity sensor
5 Calibration conditions
Environmental conditions
Environmental temperature: (23±5)℃
Environmental humidity: less than 85%RH
5.2 Standard instruments and other equipment
5.2.1 Standard humidity generator
a) Humidity range of humidity generator: (5 ~95)%RHb) Temperature range of humidity generator: 5～50℃c) Stability of humidity generator: better than 1%RH5.2.2 Precision dew point meter
JJF1076—2001
a) Measuring range: -20~+40℃ (dew point temperature)b) Expanded uncertainty (k=3): 0.2℃ (dew point temperature)5.2.3 Thermometer
a) Measuring range: 0~50℃
b) Expanded uncertainty (k=3): 0.1℃5.2.4 Digital multimeter (3.5 digits) or digital frequency meter (6 digits) DC regulated power supply (selected according to the technical documents of humidity sensor)5.2.5wwW.bzxz.Net
Calibration items
Correction value and accuracy of humidity sensor. 6.1
The temperature coefficient, stability, response time and hysteresis of humidity sensor can be selected according to user requirements. 6.2
Calibration method
Installation of calibration equipment
Place the humidity sensor to be calibrated in the test room of the standard humidity generator, and at the same time place the dew point sensor of the precision dew point meter (or lead the moisture in the test room to the dew point sensor outside the test room through a polytetrafluoroethylene tube with a wall thickness of not less than 1mm) and a thermometer. Connect the power supply and secondary instrument of the humidity sensor to be calibrated, and cover the lid of the test chamber of the humidity generator.
72 During calibration, set the temperature value of the humidity generator (such as: 20C or 25C. When the temperature is balanced, set the humidity value of the humidity generator again. Generally, from low humidity (10%RH) to high humidity (90%RH), a calibration point is made every 10%RH. The format of the record is shown in Appendix A. If there are special requirements, it can be selected according to the technical documents of the humidity sensor or the requirements of the user.
7.3 Each calibration point is stable for 10min after the temperature and humidity reach the set value. Then record the relative humidity value U (%RH) of the precision dew point meter and the output value U (%RH) of the humidity sensor every 2min, and record 3 data in total. Then make the next calibration point to After all calibration points are tested, 8. Expression of calibration results
8.1 Calculate the average value of the humidity sensor output at each calibration point. If the output value of the humidity sensor is a voltage, current or frequency value, it must be converted into a relative humidity value (%RH). 8.2 Calculate the correction value △U (%RH) of the humidity sensor at each calibration point according to formula (1): AU=Ustandard-Uindicated
8.3 Accuracy level of humidity sensor
At a certain temperature (such as: 20℃ or 25℃), the accuracy level of all calibration points within the calibration range of the humidity sensor corresponds to the maximum correction value (such as: 2%RH, 3%RH or 5%RH, etc.). 8.4 Temperature coefficient of humidity sensor
At 10℃ and 40℃, the two response values ​​of the sensor are The ratio of the maximum difference △U (expressed in relative humidity) of the response curve to the temperature interval (30℃) is taken as the sensor temperature coefficient, and the unit is "%RH/℃", see Figure 1. 2
Sensor response value %R
8.5 Stability of humidity sensor
JJF1076—2001
Source standard value R
During the calibration interval, the humidity sensor is stored indoors under natural conditions of (10~90)%RH and (25~15)℃.
8.5.1 Short-term stability (3 months): At an interval of 3 months, make the sensor humidity rise response curve at 25℃ twice, and take the maximum change value of the relative humidity of its response signal as the short-term stability, and the unit is "%RH/3 months". 8.5.2 Long-term Stability (1 year): Within 1 year, the above calibration is performed once every 3 months, and the maximum change value in 1 year is taken as the long-term stability, and the unit is "%RH/year". 8.6 Sensor response time
At a certain temperature, the humidity sensor is given a step relative humidity change U, and the time taken by the sensor to reach the response value corresponding to [△U|×63% is the sensor humidity rise response time T, or the humidity fall response time T, see Figure 2. During operation, the relative humidity of the on-site environment can be used as U, and the relative humidity of the standard humidity generator can be adjusted to U to ensure that |△U=「U,-U,≥40%RH. Then the humidity sensor in U, (or U,) is quickly placed in U, (or U), and the time required for the sensor is recorded with a stopwatch (0.1s) or a-recorder. Response time curve for rising humidity
Response time curve for falling humidity
8.7 Hysteresis of humidity sensor
JJF 1076—2001
At a certain temperature (generally 20°C or 25°C), the sensor response curve from low to high relative humidity is the rising humidity curve, and from high to low is the falling humidity curve. The maximum difference between the two response values ​​(expressed in relative humidity) is the hysteresis of the sensor (%RH). The sensor response value is /(%R11)
See Figure 3
Humidity standard value/(%RH)
8.8 The recording format is shown in Appendix A. The calibration records shall be kept for at least 2 years. 8.9 A calibration certificate shall be issued to the calibrated humidity sensor. For specific requirements, see Appendix B, C and D. Recalibration time interval
The recalibration interval (validity period) of the calibrated humidity sensor is 1 year. Appendix A
Instrument name:
Manufacturer:
Equipment number:
Recorder:
Generator parameters
U#/(%RH)
Inspector:
Room temperature:
JJF 1076—2001
Calibration record format
Original record number:
Factory number:
Inspection unit:
Biaoya Instrument (
.U/(%RH)
Condensation degree:
Indication of the inspected instrument
tu(%RH)
Pressure:
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