To identify the humidity thermocouple sensor is good or bad points

Humidity is closely linked to the human life a noun, thermocouple and humidity sensor has been widely used in various fields. At present, various types of humidity thermocouple sensors 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 thermocouple sensor, and then choose to suit the needs of products. So, we choose the humidity of the thermocouple sensor, how to judge the performance of it is in line with their own needs?

we can from the following four aspects:

1, the humidity of the thermocouple sensor temperature coefficient

moisture sensor in addition to the humidity sensitive to the environment, is also very sensitive to temperature, temperature change 0 each. 1℃。 Will produce 0. The humidity of 5% RH changes ( 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. For precise control the local space of constant temperature, constant humidity, or need to track humidity change Settings at any time, and then choose + / - 3% RH thermocouple accuracy of humidity sensor. Temperature drift of nonlinear, this need in the circuit with temperature compensation. By single chip microcomputer software compensation, or no thermocouple temperature compensation of the humidity sensor is to guarantee the full temperature range of the accuracy of humidity thermocouple linearization of sensor temperature drift curve directly affects the effect of compensation, nonlinear temperature drift compensation is not often good effect, and that only follow sex USES the hardware temperature compensation can get the real compensation effect. Humidity thermocouple 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

the humidity of the thermocouple sensor accuracy should be + / - 2% RH ~ + / - 5% RH, short of this level it is difficult to use as measuring instruments, humidity thermocouple 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, accuracy, precision humidity thermocouple sensor level should combine the long-term stability to judge, in general, long-term stability and service life is the first problem, affecting the quality of humidity thermocouple sensor drift quantity control in the level of 1% RH products rarely, usually in the plus or minus 2%, even higher.

3, humidity of thermocouple sensor power supply

some humidity thermocouple sensor to power supply requirement is higher, otherwise will affect the accuracy of measurement. Or mutual interference between the thermocouple sensor, 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 thermocouple 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. Thermocouple 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, it is recommended that the chosen frequency humidity thermocouple sensor output signal.

4, interchangeability at present, there is a widespread phenomenon of poor interchangeability humidity thermocouple sensor, the same type of thermocouple 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.

all in all, we choose a humidity of thermocouple sensor must not blindly pursue 'high, refined, sharp'. In use under different temperature humidity thermocouple sensor, 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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