CyberOptics AMS-150C, Руководство пользователя

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Relative Humidity Measurement Range
The AMS RH sensors are calibrated in the range of 2 – 85% RH. In the 0 – 2% RH range the sensors will output the
same “zero” reading, indicating that t he actual RH is in this range. Above 85% RH the sensor will output readings
that may not be as accurate as those below 85% RH.
Response Time
The AMS RH sensors have an inherent response time of eight seconds. That is, with a sudden step change in RH
level, the sensor will respond with a reading of 63% of the step within eight seconds. However, this sudden change
of RH level is difficult to achieve,
except in special test setups. It is very difficult in most “real world” situations to
totally change the air in a chamber in this short amount of time. So, the AMS HT sensors will almost always be
faster than the change in the air environment.
The HT1 Sensor and Its Thermal Environment
Because RH sensors are so dependent on the thermal environment, it is often necessary to correct the RH reading
to account for heating around the sensor. One such case occurs in the AMS, because the central (HT1)
humidity/temperature sensor is in close proximity to the AMS electronics. CyberOptics has taken great precautions
to isolate the HT1 sensor as much as possible from its surroundings. The heat path to HT1 has been constricted via
slots in the PCB. The air around HT1 is totally isolated from the air inside the AMS electronics cavity. However,
there is still a 0.8°C temperature difference between the air near HT1 and the outside surrounding air. The AMS
unit was calibrated with this 0.8°C offset, since this offset is the normal long-term environment for the sensor.
Shown below is a correction graph for HT1. The other satellite HT sensors on the AMS-300C do not need to be
corrected, since they are far away from internal heat sources. In the following circumstances, you should correct
the MultiView reading on the HT1 sensor by adding the correction to the indicated RH reading.
The following circumstances require correction.
•
When the AMS has been on for only a short period of time (less than 20 minutes).
•
When the AMS is in rapidly circulating air.