For years now, Club Mud has been firing by ear. Literally; we determined the flame adjustment on our kiln burners partially by sight, but mostly by listening. The sound of the flame at different stages of firing was variously described as a "whoosh", a whistle, a flutter. Experienced firers could tell just by the sound whether the kiln was adjusted properly.
Beginners? Not so much.
Add in the fact that, as us veteran kiln-meisters get older, our hearing gets a little less reliable, and you end up with a strong lobby for more objective measurements. So at our November meeting, we voted to install pressure gauges on all the burners of our two gas kilns. Somehow I wound up being the one to figure out how to make this work.
I went online, of course. Quickly found pressure gauges for under ten bucks, if you wanted to measure in pounds per square inch (PSI). Unfortunately, PSI is a huge measurement for natural gas. Normal pressure is a fraction of 1 PSI. What we really need are water-column inch gauges. (You know how atmospheric pressure is measured in inches of mercury? Like that, only with water, which is much less dense, hence measures lower pressures.) I found a supplier priced around $25 per, then hit a Black Friday sale, so we got two sets of four for well under $200.
Then of course, I had to figure out how to install them. They needed to go in the--fairly short--space between the on/off valve and the burner itself. We had to go from this--
--to this. (More or less. All the burners were plumbed slightly differently.) I was able to reuse a couple of 4 and 5-inch pipe nipples, but for the rest, I had to get:
4 1-inch Tee joints
4 1x1/2-inch bushings and 4 1/2x1/4-inch bushings (to narrow down the 1-inch pipe to accept the 1/4-inch gauge stem)
4 2-inch pipe nipples
3 3-inch pipe nipples
And a roll (or two) of teflon tape, the yellow stuff specially for gas fitting.
Also, a small box-end wrench, three pipe wrenches, and a big length of pipe to slip over the end of a wrench when I needed extra torque. Plus our bench vise.
It took me three visits to Jerry's (our local home-improvement chain) to get the parts I needed. Wrong measurements (A 1-inch pipe is actually 1-1/4" across, as they go by internal diameter. Go figure.). Wrong parts. Right parts, wrong size. Last minute fourth
run for three slightly longer pieces. And I still have to return three 2-1/2-inch nipples that I got because I wasn't sure 3-inch wasn't too big. That's okay, though. Now that I've finished the big kiln, I need to get the pieces I need to set up the small gas kiln with its own set of gauges.
And it is
finished; everything came apart and went back together again! All I need to do is pressure-test all the joints, seal any that leak, and it'll be ready for my end-of-January firing.
Objective documentation! I can hardly wait.ETA
: Pressure test is good! No hisses, no bubbles (you check for leaks by flooding all the joins with bubble soap. No bubbles means no gas leaks). And all the gauges read! Ran them up to warm-up levels, and they were between 2-1/2 and 3 W.C. inches. Things are looking good for my next firing.