I am setting up a climate station and I am trying to determine how long an aspirated shield needs to be on before a temperature measure is taken. Ideally, I would like to have the shield on continuously, but would require to change my power settings, which is a difficult option at this point.
If I do a T/RH measurement every 5 min, should the shield be on for at least.. 15, 30 sec, 1 min before the measurement?
Anyone knows of a paper where this has been discussed?
Thanks,
Jorge
Jorge,
Suggest you consult the manufacturer of the shield, they probably did testing and can tell you the answer.
Regards,
IslandMan
Thanks. I asked them and they said 1 minute would be enough, but it is not based on any systematic testing (engineer intuition)..
Jorge
If the shield has a fairly low thermal mass and good aspiration the limiting factor may well be the time response of the sensor, as when you turn on the fan it is like imposing a step change on sensor.
If you look up the time response of the sensor in its datasheet you can then estimate a reasonable time for it to stabilise. If the time constant (in air) is quoted at the 66% level, allow roughly 10 X that time for the sensor to settle to less than 0.1% of reading.
I'd still advise checking with the shield manufacturer first though and if they do quote a recommended startup time make sure which is longer the shield or sensor.
Couldn't you characterize it? Take some readings, turn the fan on, take some more readings, plot them, etc...