Hypothetical Question - Orchid Board

Ross · #1 05-04-2007, 04:39 PM

Is it possible to achieve 99% humidity while fans are running 24/7? This is in an enclosed terrarium. You have to know I have the answer to this.

Ross · #2 05-04-2007, 04:40 PM

Even better, as an extra point question... what use is this information?

Shadow · #3 05-04-2007, 05:43 PM

I believe it is possible.

Lagoon · #4 05-04-2007, 08:13 PM

Gee Ross I don't know for sure. If you have anything exploding let us know

Lesson the risk and get a hamster with a wheel for good air circulation

Yes I know, I'm helpful ...
Your welcome!

Ross · #5 05-04-2007, 08:15 PM

OK, I have to clarify things here. This is a hypothetical question based on reality. So, again - if one were to be able to achieve 90%+ humidity in a closed tank, would running fans 24/7 change the humidity/dryness?

Shadow · #6 05-05-2007, 05:37 AM

Just tell us the answer, please!

goodgollymissmolly · #7 05-05-2007, 06:52 AM

Yes, it is possible to get 100% humidity in a closed system. Fans running will not change the outcome, but will likely result in achieving the higher RH more quickly by providing more air/water interface opportunity. In mass transfer operations it is always preferrable to increase contact between the phases.

Two disclaimers...if system is not closed then very high humidity is unlikely unless one has the water supply and fan capacity to saturate the entire earth's atmosphere. Secondly, the pressure wave ahead of the fan blades will condense moisture on the blades before 100% RH is attained in the system. Therefore, if the fan is large and powerful it might limit humidity in the entire system to slightly less than 100%.

ScottMcC · #8 05-05-2007, 10:29 AM

I agree...the difficulty lies in getting a truly closed system. unless that tank is truly air tight, which I doubt, you're never going to get to 100%. but you can certainly get close!

also, I would think you wouldn't want a truly closed system, because you do want to have some gas exchange. unless, that is, you are going to be piping in fresh gas from a tank, but I don't know if that's a desirable option.

justatypn · #9 05-05-2007, 11:09 AM

come on Ross is goodgolly and Doc right

...so what do they win

Ross · #10 05-05-2007, 11:57 AM

OK, here's the answer

Yes!

I have happily been keeping the new tank at nearly 99% Here's the specs:

Tank not quite closed tight (approx 7 square inches openings in two 1/2" slots)

No active air exchange with outside - only passive from opening doors a couple times a week to fertilize and through the slots.

Active misting runs for 5 seconds every 4 hours. 3" 12 volt fan blows directly on orchids and front wall 24/7.

Top of tank averages 71-72 degrees F and 90-94% humidity (depends on how much time has passed since misters went off)

Bottom of tank, out of direct air movement stays approx 3 degrees F cooler (further from lights) and a constant 99% humidity.

Bottom line, new grow, new roots, new spikes, and even my Dendrobium aberrans will be blooming soon. Second species I haven't killed yet.