How to choose a good temperature and humidity sensor.
June 15,2022
cheap temperature and humidity sensor,air temperature and humidity sensor,smart home temperature and humidity sensor
The air temperature and humidity sensor is just one of the sensors. It only passes the temperature and humidity in the air through a certain detection device. After measuring the temperature and humidity, it is converted into electrical signals or other required forms of information output according to certain rules. meet user needs.
Since temperature and humidity are closely related both in terms of physical quantities and in actual people's lives, sensors that integrate temperature and humidity will be produced accordingly. A temperature and humidity sensor refers to a device or device that can convert temperature and humidity into electrical signals that can be easily measured and processed. The smart home temperature and humidity sensor on the market generally measures the amount of temperature and relative humidity.
1. Select the measurement accuracy: The selection of temperature and humidity sensors is based on the measurement accuracy, which is the most important indicator of the humidity sensor. Every increase of one percentage point means the humidity sensor is a step up, or even a grade. Because to achieve different precision, the manufacturing cost is very different, and the price is also very different. Therefore, users must tailor their clothes, and should not blindly pursue "high, refined, and sharp". If the humidity sensor is used at different temperatures, its indication value should also consider the influence of temperature drift.
It is well known that relative humidity is a function of temperature, and temperature strongly affects the relative humidity in a given space. The temperature changes every 0.1°C. A humidity change (error) of 0.5%RH will occur. If it is difficult to achieve constant temperature in the application occasion, it is inappropriate to propose too high humidity measurement accuracy. In most cases, if there is no precise temperature control method, or the measured space is not sealed, the accuracy of ±5%RH is sufficient.
For local spaces that require precise control of constant temperature and humidity, or where it is necessary to track and record humidity changes at any time, choose a humidity sensor with an accuracy of more than ±3%RH. And the requirement that the accuracy is higher than ±2%RH may be difficult for even the standard humidity generator to calibrate the sensor, let alone the sensor itself. Relative humidity measuring instrument, even at 20-25 ℃, it is still very difficult to achieve the accuracy of 2%RH. Usually the characteristics given in the product data are measured at normal temperature (20℃±10℃) and in clean gas.
2. Consider time drift and temperature drift: In actual use, due to the influence of dust, oil pollution and harmful gases, the electronic humidity sensor will be aged and the accuracy will decrease after a long time of use. The annual drift of the electronic humidity sensor is generally Around ±2%, or even higher. Under normal circumstances, the manufacturer will indicate that the effective use time of one calibration is 1 year or 2 years, and it needs to be re-calibrated when it expires.
3. Select the measurement range: The selection basis of cheap temperature and humidity sensor is the same as the measurement of weight and temperature. When choosing a humidity sensor, the first thing to do is to determine the measurement range. Except for meteorological and scientific research departments, the measurement and control of temperature and humidity generally do not require full-humidity (0-99.9%RH) measurement.
4. Other precautions: The humidity sensor is non-sealed. In order to protect the accuracy and stability of the measurement, try to avoid using it in an acidic, alkaline and organic solvent-containing atmosphere. Also avoid using it in a dusty environment. In order to correctly reflect the humidity of the space to be measured, it is also necessary to avoid placing the sensor too close to the wall or in a dead corner where the air is not ventilated.
If the room being tested is too large, multiple sensors should be placed. Some humidity sensors have relatively high requirements on the power supply, otherwise the measurement accuracy will be affected. Or the sensors interfere with each other or even fail to work. In use, a suitable power supply that meets the accuracy requirements should be provided according to the technical requirements.
cheap temperature and humidity sensor, air temperature and humidity sensor, smart home temperature and humidity sensor need to pay attention to signal attenuation when long-distance signal transmission is required. When the transmission distance is more than 200m, it is recommended to choose a humidity sensor with a frequency output signal.