To identify the humidity sensor is good or bad points

Humidity is closely linked to the human life a noun, the humidity sensor has been widely used in various fields. At present, various types of humidity sensor on the market, its material, structure and process is different, the performance and technical indicators is differ in thousands ways. From our users use perspective, the first thing to understand need what types of sensors, and then choose to suit the needs of products. So, we choose the humidity sensor, how to judge the performance of it is in line with their own needs?

we can from the following four aspects:

1, the temperature coefficient of humidity sensor

moisture sensor in addition to the humidity sensitive to the environment, is also very sensitive to temperature, temperature per 01 ℃. Will result in a change to the humidity of 05% RH ( Error) 。 Use occasions if difficult to achieve constant temperature, high humidity measurement accuracy is not appropriate. Some moisture sensor under different relative humidity, its temperature coefficient and difference. In most cases, if there is no precise temperature control means, or measured space is sealed, the precision of + / - 5% RH is enough. Accurate control for the local space of constant temperature, constant humidity, or need to track humidity change Settings at any time, to choose more than + / - 3% RH precision humidity sensor. Temperature drift of nonlinear, this need in the circuit with temperature compensation. By single chip microcomputer software compensation, or without temperature compensation of humidity sensor is not the full temperature range of the precision of the linearization of the humidity sensor temperature drift curve directly affect the compensation effect, the nonlinear temperature drift compensation is not often good effect, and that only follow sex USES the hardware temperature compensation will get real compensation effect. Humidity sensor working temperature range is also important parameters. Most of the moisture sensor is difficult to work in 40 ℃ above normal.

2, accuracy and long-term stability of

humidity sensor accuracy should be + / - 2% RH ~ + / - 5% RH, to reach this level it is difficult to used as measuring instruments, the humidity sensor to achieve the accuracy of + / - 2% RH ~ + / - 3% RH is relatively difficult, usually feature is given in the product information at room temperature ( 20℃±10℃) And clean gas measurement. In actual use, due to the influence of the dust, oil pollution and harmful gas, use a long time, will produce aging, precision, accuracy level should combine the long-term stability of the humidity sensor to judge, in general, long-term stability and service life is the first problem, affecting the quality of humidity sensor drift quantity control in the level of 1% RH products rarely, usually in the plus or minus 2%, even higher.

3, the humidity sensor power supply

some humidity sensor to power supply requirement is higher, otherwise will affect the accuracy of measurement. Or mutual interference between sensors, even unable to work. Metal oxide ceramics, polymer and lithium chloride humidity sensitive materials such as dc voltage, can lead to performance change, even failure, so this kind of humidity sensor can't use dc voltage or dc component of ac voltage. Must be an alternating current power supply. When using, should according to the technical requirements to provide appropriate, conform to the requirements of the precision of power supply. Sensor need for remote signal transmission, to pay attention to the attenuation of the signal problem. When the transmission distance of more than 200 m or more, the proposal chooses humidity sensor output signal frequency.

4, interchangeability at present, there is a widespread phenomenon of poor interchangeability humidity sensor, the same type of sensors are not interchangeable, seriously affecting the effects of using, to add to the difficulty, maintenance, debugging, some manufacturers has made efforts in this regard, ( But the interchangeability is still very poor) Good results have been achieved.

in short, when we are choosing a humidity sensor must not blind pursuit of 'high, fine, sharp'. Use humidity sensor under different temperature conditions, for example, its value to consider the influence of temperature drift, try to avoid in acid, alkali and organic solvent atmosphere and dust used in the larger environment.

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