[VAC] Re: 1962 Globetrotter Water Pump Question

[Don Horn <donhorn@xxxxxxxxxxxxxx>]

I'd guess that the last years for the compressed air systems were around
'62-64.  My '63 Avion, modeled in many ways after Airstreams of the time,
has the same system.  When you fill up to city water, it automatically
pressurizes the tank if you keep the system closed.  I use a regulator to
keep the pressure down to about 45-50psi.  IIRC, the system is rated to
about 65psi, and city water lines can get a lot higher than that.  The
compressor has an automatic switch.  I seem to recall that it comes on at
about 20psi and shuts off at around 35psi.  The system appears to be very
tight--it holds full pressure a long time, when no water is being drawn.

It also has a hand pump built into the filler cap in case you don't want to
run your batteries down while boondocking, and a tire fitting as well for a
hand pump, portable air tank, or other compressed air source.  The main
drawback is that as the tank empties, there's a lot more air to compress,
and the pump runs a long time.  I think it draws about 7-9 amps.  Sometimes
I pump with the hand pump at the same time the compressor is running, to
save battery power.

I've considered converting to a demand pump, but this system works well
enough, and the plumbing requirements to convert, although probably not
extremely difficult, wouldn't exactly be trivial.  My compressor is a
Grover, and I found that they still make very similar models, only now
they're made for air horns for trucks and boats.  There's a current model on
their web site that looks like it would be nearly a "plug & play"
replacement, although if mine ever fails, I'll probably just convert to a
demand system.

When you try out your compressor, make sure it's filled with SAE 20 oil.
3-in1 sells a  20-weight oil in a small can (blue and white, not the red and
white can) or you can just use some clean spare single grade motor oil.
There's no air filter in the line, but I haven't noticed any problems with
oil in the water, and of course water in the compressed air is not a
problem.  

To test the system, fill it with city water through a regulator with the
filler cap shut.  Bleed all air out of the faucets, water heater, etc.  If
you have a tire-valve fitting somewhere in the system (on the filler neck?),
check the air pressure after filling.  Then run water out of one of the
faucets, holding a pressure gauge on the system, and note at what pressure
the compressor cuts in.   Shut all faucets, and see if the compressor brings
the system back up,  and if so, at what pressure it cuts off.

For a general system leak check, pressure up the system using city water as
above, check the pressure, and continue to check it periodically to see if
it holds.   I'd start out at small intervals, and if it seems to be holding,
check back at longer intervals until you notice a significant drop.

Don