Humidor, Coolidor Temperature Variations

[monkey66]

Could also be down to the fact that analogue hygrometers are crap at giving your humidity readings in the first place, as the temperature should not be that big a factor with the salt test

Yup, they are inconsistent and fairly useless for our world, although they look pretty.

It is possible that the metal spring in the analogue meter is influenced by temp (but this is almost nothing to do with actual humidity).

[mrcigar]

Could also be down to the fact that analogue hygrometers are crap at giving your humidity readings in the first place, as the temperature should not be that big a factor with the salt test

My hydro is as cheap as they come, but in terms of repeatability it's surpisingly good. I wouldn't go as far as say they are crap because they are analogue - it gives a reading of 75% RH in the jar at 21C and returns to it again when I put the jar back in a 21C room after having it outside.

I agree though, the temps should not influence the RH. In fact, the RH should remain steady from 0C to 50C. FYI, colder = higher RH; warmer = lower RH.

Warmer air has the capacity to hold more moisture than colder air. By placing the jar outside in the cold, the temperature drops, therefore reducing the capacity of the air to retain moisture. The RH changes as a result and may require more time than I allowed to stabilise. Perhaps if I conducted the test outside in the cold the RH would have read 75% and dropped when bringing the jar back inside to 21C. If this were the case, the warm air would encourage moisture to be released into the air, and stabilisation seen sooner.

I was interested to learn recently that Lloyds Register preferred us to use analogue equipment during some pressure and thermal response testing on a sat diving chamber.

[mrcigar]

But did the RH return to 75.5% after the temp had changed and the the RH had chance to return?

Eddie, yes it did, see response to pedro.
Cheers

[Eddie]

Eddie, yes it did, see response to pedro.
Cheers

I think you are answering the wrong question (I didn't word it too well). If you have it inside at 75%, then stick it in your fridge the humidity will rise. After a few hours in the fridge will it then read 75 again?

[mrcigar]

I think you are answering the wrong question (I didn't word it too well). If you have it inside at 75%, then stick it in your fridge the humidity will rise. After a few hours in the fridge will it then read 75 again?

Probs so, yes. I was too impatient and was too interested in the immediate resilts to wait. However, I would be quite confident that the RH would settle to 75% after a few hours of being in the fridge.

[mrcigar]

What this does show, however, is that temp changes have a huge immediate influence on RH.