[Clayart] fast fire clarification
jefflawr at gmail.com
Thu Oct 6 14:35:42 EDT 2016
The best of them(I use Eclipse atmospheric mixers) use the gas jet itself
to entrain primary air, which is controlled in volume by the air shutter.
incidentally, I have seen air shutters opened wide, despite the
manufacturers' suggestion (in the case of Eclipse) that 3.5 turns is full
air. More than that creats turbulence which reduces efficiency. Anyway, the
machined throat that Vince cites is a low pressure area which draws air
into the mixer in a very effective way. ... Eclipse Mixers are a thing of
beauty, IMHO. Many on this list probably think I am paid to praise their
I've demonstrated many times that a wide range of burners that work well in
other kilns can be used to achieve abysmal results. This range includes
Ward forced-air burners, ancient GACO burners, newer MR-series burners and
finally, Eclipse mixers, which I tried based on Hank's suggestion.
The MR-750 is the well-regarded workhorse of venturi burners, but comparing
it to the Eclipse system is to compare a machete to a scalpel. A couple of
years ago, obsessing about primary air led me to measure it for both. Using
identical orifices and under gas pressures from 3-12wci, the MR-750 topped
out at about 45% efficiency (i.e. 45% of air needed to fully burn the gas)
while the Eclipse maximum ranged from 67% at higher volumes to 95% for low
volumes. As Hank pointed out, there's a point where opening the shutter
more doesn't do anything good. Since primary air mixes and burns better
than secondary air, which can grope kiln contents like an oxidizing
tentacle, this persuaded me he was right to praise Eclipse burners (tho I
also proved in my kiln they could be used for evil results.)
The mixers come with adjustable needle valves for "dial-an-orifice"
capability. Hank replaced these with fixed-hole spuds, but my plumbing
isn't as neat as his. Hence, I'm glad I can tune individual mixers.
If you're looking at venturi burners, you should consider Eclipse
mixer/burner tip systems. Full line is available from Flameco Industries,
in Tulsa (918) 832-1100. If you call Eclipse directly, they'll send you to
their corporate sales guys, who for some reason charge twice as much.
Thanks again for the tip, Hank!
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