large surface area to cool the air. There is a short
section of ¾” pipe at the bottom (Figure 2) where a tee provides the inlet
from the compressor, and a drain point via a ¾” ball valve. The top of the
2” section reduces to ¾” again before traversing the basement and entering
the bottom of the garage wall (Figure 3). The pipe slopes slightly down
towards the garage.
Immediately after entering the garage there is a ¾” tee, the bottom of which
goes to a ball valve drain point while the top extends up the wall to
another ball valve (Figure 4) which isolates all of the outlet couplers and
the 100-foot hose reel from the supply of air. The isolation valve is handy
since the couplers leak a little bit. If I forget to turn off the isolation
valve the compressor will run occasionally, usually in the small hours of
the night. BRRRRRRR.
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Figure 4 - Isolation valve, filter, |
Above the isolation valve I have a tee which feeds the
100-foot reel via a filter with a pressure gauge. The pressure gauge is
easily visible and is handy just to confirm the pressure in the pipe.
From the top of the tee the pipe enters an elbow and extends on a slight
upward slope to three outlet couplers above the work area. All of the pipe,
fittings, and ball valves are ¾”. The outlet couplers are standard ¼” NPT
using reduction bushings to fit the ¾” tees in the main pipe.
Since I had no experience of plumbing, I measured everything and laid out
the design in a computer drawing package. I was then able to take the
diagram to a plumbing supplier and have all the pipe cut to length and the
fittings supplied. Since the plumbing supplier knew what I was making, he
even fitted some sections together to save me some additional work.
In use, the compressor tank is set at 125 psi and I have
the regulator adjusted for a line pressure of 90 psi which is suitable for
the drill. I have a separate pressure regulator on the riveter which
performs best between 25 and 40 psi depending on the size of the rivets.
Simple, common sense design choices can provide a workable distribution
system. Firstly, use the pipe itself as a heat sink. The longer the run from
the compressor, the cooler the air will be at the outlet. Slope the pipes so
that water condensing inside can be collected at low points and drained via
ball valves. If possible, provide one section of larger diameter pipe close
to the compressor. This provides a larger surface area as a heat sink and
slows the flow down so that the air has time to cool. Be creative about the
selection of fittings; you don’t need an expensive 2” ball valve if you can
install a 2”- ¾” reduction coupling and use a ¾” ball valve.
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Figure 5 - Air coupler fitted to ¾” tee |
I initially estimated the installation would cost around
$150 but it came in at just under $200 with all the outlet couplers. Yes, it
was a considerable investment for a one-man shop but I have a safe and
pleasant work area. Since I installed the system I've hardly given it
another thought except to appreciate the convenience it provides by having
air available when and where I need it. I've since purchased a couple of
paint spray guns and a 3” disk cutter. I’m more than happy that I took the
time to install the compressed air system correctly.
Editor’s note: Neil Hulin came all the way from Australia via
England “just to join Chapter 174”, and has been actively involved, along
with his wife and their 5 young aviators, in building a Zodiac 601XL.
Daughter Maia and sons Kael and Bryn, ages 6 - 11, ran the riveting class
for the Scouts at Clermont County Library’s Aviation Heritage Day last
summer. Neil has offered to provide occasional updates on his project for
the newsletter and web site, as well as articles on various aspects of
building.