Humidity sensor introduction

Humidity sensor introduction
Select measurement range
As with measuring weight and temperature, the humidity sensor is selected first to determine the measurement range. In addition to meteorological and scientific research departments, temperature and humidity measurement and control generally do not require full wet range (0-100% RH) measurement. In today's information age, sensor technology is closely integrated with computer technology and automatic control technology. The purpose of the measurement is to control, the measurement range and the control range are collectively used. Of course, for those who do not need to engage in measurement and control systems, it is ok to directly select a universal hygrometer. The following are some application areas for different requirements of temperature and humidity of humidity sensors for users' reference ( see Table 1) . The user proposes the measurement range to the sensor manufacturer according to the needs. The manufacturer gives priority to ensuring that the performance of the sensor is consistent and consistent within the scope of use, and obtaining a reasonable performance-price ratio is a mutually beneficial thing for both parties .
Select measurement accuracy
As with the measurement range, measurement accuracy is the most important indicator of the sensor. Every increase - percentage points. It is the last step for the sensor, even the previous grade. Because of the different precisions, the manufacturing costs vary greatly, and the selling price is far from the same. For example imports an inexpensive humidity sensor only a few dollars, but only for 1 full wet calibrated with humidity sensors to drive a few hundred dollars, a difference of nearly a hundred times. Therefore, users must tailor their clothes, and they should not blindly pursue " high, precise, and sharp " . Welcome to the company's official website http://
Manufacturers often give the accuracy of their humidity sensors in sections . Such as, the cryogenic section (0 to 80% RH) was ± 2% RH, while the high humidity sections (80-100% RH) was ± 4% RH. And this accuracy is the value at a given temperature ( eg 25 °C ) . Use humidity sensors at different temperatures. Its indication also takes into account the effects of temperature drift. It is well known that relative humidity is a function of temperature, which severely affects the relative humidity within a given space. The temperature changes by 0.1 °C . A humidity change ( error ) of 0.5% RH will be produced . In the case of use, if it is difficult to achieve constant temperature, it is not appropriate to propose excessive humidity measurement accuracy. Because the humidity is also erratic with temperature changes, the luxury measurement accuracy will lose its practical significance. Therefore, the first thing to control the humidity is to control the temperature. This is why a large number of applications are often temperature and humidity - body sensors rather than just humidity sensors.
  　 In most cases, the accuracy of ±5% RH is sufficient if there is no precise temperature control or if the space being tested is unsealed . For applications requiring precise control of constant temperature, constant humidity local space, or where it is necessary to track and record humidity changes at any time, select ±3% RH
The above precision humidity sensor. Corresponding temperature sensor. The temperature measurement accuracy must be ±0.3 °C or more, at least ±0.5 °C . The requirement that the accuracy is higher than ±2% RH may be difficult to achieve even the standard humidity generator of the calibration sensor, not to mention the sensor itself. According to the article in the humidity room of the National Standards Research Center, “The relative humidity measurement instrument, even at 20-25 °C , is still difficult to achieve 2% RH accuracy. ”

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