davediaz@netrail.NET (David Diaz) writes:

This was all good with the exception of temp for condensation. Condensation can occur at just about any temp (within reason) that is what Dew Point is. Humidity is Dew point/(room) Temperature. When they match you have humidity of 100% and start to see condensation/fog. Anyway this is from flight school. I have heard different engineers recommend 40% humidity and maybe 67.5 degrees temp. Something about enough humidity to avoid static dischargies etc...??

Normally people pay consultants a lot of money to go look this stuff up in libraries :-) You are correct, it is actually a XY curve plotted with both relative humidity and temperature. Condensation/fog is not good for a co-locate space. In addition to electrostatic discharge other issues include corrosion, fungial growth, affect on the other material stored in the area, and of course comfort for the human occupants. Go to far in any direction, and you'll have problems. You are looking for the sweet spot. The problem for a co-locate operator is there isn't one, but several depending how the occupants decide to use the space. Further, what is 'acceptable' may vary depending whether you are the one paying the utility bill, or if someone else is paying it. cigars 70f/70% R.H. wine 56f/>20% R.H. mag tapes 63f/25% R.H. (> 10yr storage) mag tapes 70f/40% R.H. (< 5yr operating) museum objects 70f/50% R.H. photographs 68f/35% R.H. color photos 40f/35% R.H. books/paper 70f/35% R.H. "clean rooms" 72f/50% R.H. You'll notice I didn't list 'co-locate space'. If you do some research you will find the 'optimum' settings are always one study away from changing. As researchers discover new and inventive ways for Murphy to attack, they also discover the previous settings sometimes created the perfect petri dish for problems to grow. People get very religious about the 'correct' environment. And we haven't gotten into things such as filtration for dust, smoke, gases, pollutants. Or other issues like electromagnetic interference, vibration, lighting, acoustic noise, sesimic stability, floor loading, fire prevention and resistance, etc. Government and technical sites of interest Magnetic media storage http://www.nml.org/ Books, paper, photographs http://www.loc.gov/ General storage http://www.nara.gov/ Electrostatic discharge http://www.eosesd.org/ -- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation