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new shop setup, etc
Well then my own .02:
I too have a Gast regenerative-type blowers. In addition to being
relatively quiet to start with (mild whining noise, all but gone when
stuffed behind a wooden barricade in the corner) they are much cheaper than
the Roots type blowers -- for a one-person shop figure $500-$600 new,
including inlet air filter, for a one-man-shop (around 42 CFM, if I recall
right).
I use propane with a copper 3/4" main line, 1/2" branch lines, which are
plenty adequate for a one-man shop.
I also have a solenoid valve on the main line, shutting off all gas in the
event of power failure and consequent gas buildup; the one I use is 3/4"
diameter and so poses no restrictions on gas flow. Being special for propane
I think it ran about $75.
VENTING is indeed important; consider that not only the air from the
torches should be fresh, but a regular supply just for breathing is a good
idea too -- phosphor dust is unhealthy stuff (ever see the Material Safety
Data Sheets for various coatings?) not to mention that mercury vaporizes at
room temperature.
> it's a great challenge to put it all together
>at considerably less cost than some of the all-in-one packages I've seen
>advertised.
no kidding. Kind of astounding what you can pay if you're not careful, or
resourceful, or both. My own worst deal was a bombarding milliammeter for
$140; I tracked down the manufacturer and posted the results ($50 when
ordered direct) in the Neon News (my own sweet revenge).
> The proper pressure for torches for neon is 2 lb. air and 1/2 lb. of gas.
>That ratio may be slightly different for propane.
Years ago we had problems with torch fluctuation at the two-man shop I
worked for. Rather than replumb the place I upped the propane pressure to 10
psi -- worked like a charm. I continue to use this pressure, even though
I've only got one set of torches. But then, I also have kickswitches for
turning off the crossfire and ribbon after each bend -- having a higher
pressure means no waiting around when kicking it on. I also use oxygen to
speed up bending time -- but that's another thread.
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> the voltage will take the path of least resistance to ground and I
>would prefer that path to be through the tubes. Why give it a choice? The
>ground philosophy comes from the notion that a short to ground will trip a
>breaker somewhere or other protection device. With transformer secondaries
>that doesn't happen. The other notion is that if you have metal you won't
>have fire. The theory is that the metallic conduit or greenfield will "sink"
>the voltage to earth and eliminate a potential difference to surroundings. I
>find this to be incorrect in practice.
> The idea of reducing the secondary
>voltage of transformers to 10k max will only cause more problems.
Weeell, I guess we can agree to disagree. Part II of my own "o-so-safe"
transfomer installing system has me using 9,000 MAX outside, 12,000 max
inside -- Hilo Hawaii is the wettest city in America (though the "being in
America" part is arguable); I made a tidy living when we first moved here by
overhauling existing, chronic-problem signs and using multiple smaller
transformers. Big ones jump big gaps; small ones do not. To my knowledge the
8,000-volt limit on German and Dutch transformers have kept neon fires there
pretty unheard of. (Ed DeZuzio, new list member, can correct me if I'm wrong
:^) ) Then again, everything in Holland is made out of brick anyways --
nothing to burn.
Of course the path through the tubes is where the current will want to flow,
given that it's a half-decent installation of any type. It's when a tube
breaks or otherwise fails that problems develop -- and I've seen a lot more
melted plastic than melted metal conduit. I've yet to touch a metal-conduit
installed sign and get a shock, even without separate grounding wires as per
UL; can't say the same for nonmetallic.
I don't think the notion of grounding ANYTHING is ever to "trip a breaker
somewhere" -- with the exception of GFCI-type breakers (which, by the way,
don't work with neon.) The notion of ground is to provide a safe path, as
opposed to through your body or through flammable materials.
I've seen arcing inside metal conduit that has evidently been going on for a
long time, without spreading -- by giving the voltage a place to go, it's
happy and content -- as opposed to seeking a path, say, through damp wood
and starting a fire that way.
> I
>have seen many a job where the electricians kept adding more and more ground
>wires in an attempt to provide sufficient pathways for this voltage to bleed
>off without success.
Well, I've never seen a case where a good ground doesn't stop the arc, so
I'm surprised by this.
> One interesting point
>is that transformer manufacturers recommend that you load on the heavy side
>rather than the light side which is how I do it also.
Yep -- and then the Actown supplier told me that the reason people were
having trouble with burnouts was from UNDERloading. I smiled and politely
excused myself. Underloading's main problem is that it adds to the
transformer heat -- so as I said before, I work hard to keep my transformers
cool. Something I regularly do is leave the cover off the box, if it's in a
drop-ceiling location. I used to do this ALL the time; now I don't do it in
restaurants or other "food is present" locations -- rats provide a pretty
good path to ground!
> I might have
>lost 2 transformers in 20 years
I'm jealous. By the way, I'm curious if other folks who load with a
milliammeter use 80% of the ACTUAL short-circuit, or the NOMINAL short
circuit? A "30mA" transformer will rarely put out a real 30mA; these days
it's often around 28 - 29 mA (I've seen as low as 24mA!); I've got some from
1928 (real beauties!) that put out 34mA (!) -- all with a "30mA" nominal
rating on the nameplate. So I've always gone with 80% of actual
short-circuit; I've also written Paul Davis and some others about this, and
never gotten an answer.
> I don't do them by UL 48 or NEC exactly
Me neither. These codes are formulated entirely for safety, not for sign
longevity. (see note above on transformer box lids).
> BTW, the local
>inspector has NEVER bothered me about my installs. He calls me for advice.
Someday I imagine there will be an inspection of a finished sign somewhere
in this state. Hopefully I'll recover from the shock.
(Though last month the Maui County Council, in their infinite wisdom,
decided to immediately adopt strict licensing requirements for all sign
shops, such that one can't get even get a sign permit without a Contractor's
License. A Contractor's License is a big deal here -- figure $800 and four
months if you're lucky -- and they put the legit folks there out of
business. The only company on that island with such a "Sign Contractor's
License" is, get this -- an electrician. And we know how much THEY know
about neon installation!)
> Looking forward to the commentary.
Looking forward to the commentary back.
-Ted Pirsig
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