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Re: Re: more air reg

Continuing the air pressure discussion, Al Hooton wrote:

> From:          Al Hooton <al@teleport.com>
> Subject:       Re: more air reg
> Reply-to:      neon-l@netcom.com
> 
     { all except current questions snipped }
  
> - Approximately how heavy is the plug?  In my situation the outer tube
>   is somewhere around 4 lbs or so.  I suspect your plug can be lighter
>   than this?

It's only the weight of the four pieces of 3/4" pine (approx 1 1/4 diameter) 
and the carriage bolt that holds them together (about 4-5" long) plus any nuts 
added to the excess length of the bolt.  I haven't actually weighed it, but the 
total assembly can't be more than a few ounces.

The air column above this piston assembly is what cuts down on the weight 
requirement.  Since upward movement on the piston is trying to compress the 
column, (as long as the top of the pipe is capped), it can eliminate a lot of 
iron.  If I run with the pipe uncapped, I have to put in a bunch of pieces of 1"	 
black pipe to ride on top of the piston to get the same kind of air pressure at 
the fires.

But gosh, there are so many variables involved that it's difficult to 
understand exactly what effects happen at the other end of the pipe when any 
one of them is changed.  For example, if I were going to take my own design 
(which is version 394.6 all evolved from the same raw materials) and build it 
from scratch--neatly and cleanly--I'm sure I'd find some interesting 
differences in how it operates.  Just the variation in internal roundness from 
one piece of PVC to another would impact final best-fit piston sanding, then 
from there it would affect how much air normally escapes past the piston, which 
in turn changes how much raw pressure there actually is to regulate, etc. 

> - You mentioned not needing a surge tank.  I don't either, but in addition
>   to the regulator I've got around 10 feet of 2 inch PCV to get from the
>   blower to my air manifold (this length is needed to get from my attic down
>   to my shop area).  So, there's a pretty good volume in there to act as a
>   surge buffer.  I was just wondering what the diameter of the air feed is
>   between your blower and your air manifold, and how long it is. You might, in
>   effect, have a 'surge tank' there, as I do.

The blower is in a box next to the end of the bending bench, and it has
probably 20' of 1 1/2" pipe going to the outside air intake.  Its output goes
about 3' to a tee which then goes about 4' to the regulator stack one way and
maybe 3' to the first burner valve the other way.  My fires are steady enough
that once one is lit and adjusted it will stay that way, but if I did a lot (or 
when I start doing a lot) of having multiple fires going and turning some on 
and off at random I might need a bit more stability in the form of a surge 
tank.  Sounds like almost anything of sufficient internal volume will work, and 
I have plenty of options for splicing one in at either end of the manifold.  

Before I did that I'd probably try raising total regulated pressure in the 
manifold to maybe 3 psi and dialing it down at each fire with an adjustment to 
the stop valve.  One thing that happens to me sometimes is that it's easy to 
fall into doing a lot of tinkering with the hardware...and in the process not 
making a lot of progress in learning the art of bending glass.  Gotta watch 
myself on that one!  

>         Thanks for doing your GIF!
Thanks for the inspiration and the motivation to sit down and wrestle with 
Corel Draw until I got something useable!
 
Cheers,

JD


--
J.D. Schueler
lightem_up@socketis.net