[gray-b-gon:1] What's new in 2010 for GBG evapotrons

[Ember]

It was a very successful year! 2009 was the first year that other
burners built and brought their own GBG's -- some via the workshop I
led, others with their own designs or with improvements on mine.

I saw three problems that needed correcting, and so far I've got two
and a half corrections.

1. Dismantling last year meant collapsing the drum for transport by
cutting off the mesh and twine This year, the drum axle can be
collapsed and removed for storage without damaging the fabric. Re-
erecting the drum now takes a minute or two to re-insert the axle,
rather than the 30-45 minutes previously required for a complete
rebuild.

2. Everyone knew sanitation was important, but no one was sure how to
do it properly. Last winter I corresponded with an expert from Clorox
Corp; I described the situation, he gave me advice, I wrote some new
paragraphs which he reviewed, and we now have a simple and reliable
rule for treating water. It takes into consideration the dust and
other contaminants, the temperatures, and other sources of
uncertainty.

"That's amazing!", you think. "How can one rule be so broadly
applicable?" Well, here it is:
1. Add bleach and wait a half hour.
2. If there isn't a tang of bleach in the pond, add some more.
3. Repeat.

A somewhat more elaborate version of this is now Step 30 in the
construction guide.

3. High winds produce huge "evaporation" rates, but they do it by
blowing droplets off the drum and onto the nearby playa. This doesn't
bother the BLM -- we're "treating and dispersing" -- but it can be a
problem for the campers just downwind. Lifting the drive belt from
the propeller pulley helps temporarily. I'm going to experiment with
low wind shields around the drum this year.


--
Subscription settings: http://groups.google.com/group/gray-b-gon/subscribe?hl=en

[Ember]

One more minor change, to correct a brain check. About wheel sizes:
I've been advising 24-, 26-, or 26-inch wheels for the propeller and
drum. It occurred to me that I've never tried a 24-inch wheel (whose
rim is actually only 21" across.)

Now, 24-inch wheels would work, though they'd probably reduce
evaporation rates some on the drum, and for a propeller you might need
to extend blades beyond the rim. But for now the construction guide
advises only 26- and 27-inch wheels.

By the way, a 26-inch wheel (without the tire) is really 22-1/2
inches, and a 27-inch wheel is about 25-1/2.

[Ember]

Here's another change. For building the pulley, the construction
guide specified a 7/8"-long piece of 1-1/4" PVC. At this pulley
width, some fat stocking knots would hang up going through the
pulley. The freehub body that the pulley's designed to ride on is
about 3/16" longer than the pulley width, so in the guide I have
widened the PVC piece from 7/8" to 1". If a pulley now seems too wide
to fit on the freehub, it's probably due to the inner flange being too
wide. Test: push inward on the inner flange and see if it wants to
spring back. Trim an eighth of an inch off the raw edge, and see if
the flange now sits firmly on the hub.