Outdoor misting systems cool down hot dry areas, such as shade structures at Burning Man. Arizona Mist (http://www.azmist.com/) makes several "low pressure" mist systems, but you can also make your own.
I checked retail prices for these mist systems at a local hardware store. I found this information:
Arizona Mist systems and prices: -------------------------------- System 2000: $50 Kool Kit: $50 Mini Mist: $28
This store tends to be overpriced by anywhere from 20% to 100% over other nearby stores, but none of the other stores had the Arizona (or any other brand) mist system. (I've heard that Harbor Freight sells misting systems.) Also, these prices were checked in winter, when you would think they would be cheaper, but I think this particular store does not really have sales or seasonal pricing. I would guess that these same kits, if found in a place with reasonable pricing, would cost about 30% lower than this.
If you check out the specs on these systems, (have a look at the Arizona Mist web site, or check them out at a store) you will probably come to the conclusion that the System 2000 is the closest thing to what would be best for a large dome (800 square feet), and the Mini Mist or Mister Cool would be well suited for the small dome (200 square feet).
I decided not to buy these systems because they are too expensive and the more affordable one is a little inflexible. I instead built my own misting system out of stock parts from RainDrip (http://www.raindrip.com/) and DripMaster. RainDrip and DripMaster make similar items, and are mostly interchangeable.
These drip irrigation systems can be categorized by the diameter and type of tubing used. The smallest is 1/4", flexible, which supports the lest amount of water flow, and can have about 15 misters on a single line. Another type is 1/2" flexible, which can have many more misters on a single line -- probably over 100. You can also increase the number of misters on a single line by increasing the pressure of the water feeding into the system, but for lo-tech Burning Man purposes, we will probably want to expect pretty low pressure (around 25 PSI). By comparison, the high pressure systems are around 1000 PSI and require special pumps, and a garden variety garden faucet probably put out from 20 to 70 PSI (just my guess).
The system I concocted uses
With these parts, making the misting system was trivial: I sliced up the tubing to lengths appropriate for the placement of the misters I wanted, inserted tees between those lengths, and attached the misters at the remaining prong of each tee, using a very short piece of tubing (roughly 1" long) to connect the tee to the mister.
tee fitting | | V --------------------------- --------------------------------- 1/4" tubing ============== 1/4" tubing --------------------------- || --------------------------------- || |||| |||| | | | | <---- short piece of 1/4" tubing | | |||| |||| || || --\ ||===| <---- flow control knob || --/ || |||| | | \/ <---- mister head
My 6-mister system cost around $17. This system is comparable to the "Mini Mist" system by Arizona except that theirs does not give you the option of where to put the misters -- the tubing is pre-cut. On the other hand, the Arizona system is easier to deal with since it is mostly pre-assembled.
When I turned the system on inside the small dome, fine mist came from all directions. It got very wet and muddy in there. I turned off all but 1 mister (the one in the center), and found that it was sufficient, so the other 5 were redundant. There was so much water coming out of all of the misters that it was almost annoying. You could use the dome as a shower instead of a place to be cool. This is a feature, not a bug, since the misters I use have flow control valves, so it is fast and easy to convert from a nice cool mist to a soaking deluge.
A few notes:
The clamps will also help keep your system assembled when you are tugging on the tubing to set it up or pack it away.
The barbs, once inside the tubing, are quite difficult to unplug, but I have been playing with this in very cold temperatures. When the temperature gets up to 115 F then the tubing is likely to be very soft, and the barbs might come out easily. I have no easy way to test this ahead of time so I am playing it safe and using plenty of high-pressure clamps.
If all of the flow control valves on a line were closed, then the pressure in the line gets so high that water leaks in several places -- where ever there was a "seam" or connecter. This was the case without high-pressure clamps in place.
The hose-to-tubing adapter leaked but was easy to repair. After a year of operation in temperatures ranging from desert hot to sub-freezing, the portion of 1/4" tube which slips inside the adapter hardened and failed to make a consistently proper seal. To repair the problem I removed the 1/4" tube from the adapter, cut off about 1 inch of the tube to remove the narrowed, hardened area, and re-inserted the tubing. The process took under 1 minute. The resulting seal did not leak.
To supply the pressurized water, use a portable hand-pump sprayer. Solo sprayers have garden hose attachments on them, and they are available at Home Depot.
A wide variety of automatic, battery powered and self-powering water timers are available, in a wide price range.