I built a tig cooler using a diaphragm pump, the type typically use for
agricultural sprayers. The pump is rated at 1.8 gpm @ 60 psi. It is made by
Shurflo, and is periodically on sale at Northern Tools for less than $60. A
12VDC power supply is required; an old PC power supply works great. Even
though the pump is rated for continuous duty the motor will become very hot
after about an hour of use. I installed a small fan, also salvaged from an
old pc, blowing on the motor. With a fan the motor runs cool even after
several hours of continous use.
One characteristic of a diaphragm pump is that the pressure is pulsating. It
does not deliver a constant pressure like a gear pump does. This is not a
problem, because the hose leading to the torch is long, small diameter, and
flexible. The hose works to average the pulses. I can feel a significant
pulsation in the hose immediately after the pump, but there is almost no
pulsation noticable at the torch, even with a 12' hose.
My system uses a 5-gallon bucket as a reservoir. A bypass valve is used to
regulate the pressure. I have found that under most circumstances only
around 40 psi is needed to cool the torch. I bump the pressure up to 50 psi
when I am welding aluminum at high amperage. Due to the pulsations from the
diaphragm pump, if you connect a pressure gauge you will need a "snubber"
ahead of the gauge. I use a small needle valve for that. If you search the
web you will find plenty of info to describe a snubber.
Overall, I spent about $90 on my cooler, most of that for the pump. Except
for the pump and the left-hand hose fittings, everything was either salvaged
or purchased at a local hardware store. It's ugly as a cow's butt, however
it works well. I have noticed that during extended welding sessions at high
amperage the water does become warm, but even so it still effectively cools
the torch. You would need to be using big amps on a big torch to overwhelm
the 4 gallons or so of water in the bucket. A radiator is probably overkill
unless you are doing commercial welding at > 200 amps, or you live in a hot
climate. Ten feet of 1/4" copper tubing in a coil on the return side of the
circuit would probably be an adequate radiator for most home uses.
I also installed a safety fuse on the coolant return/power cable. This is a
device that is inserted inline on the return hose. If water is not flowing
or if inadequate water is flowing the fuse will blow and cut the power
before the torch is damaged. I think I paid about $35 for that item. Be sure
to buy some extra fuse links, they will occasionally fail because of arcing.
It doesn't happen often but when it does you will need a spare link. The
fuse links are cheap, about $7 or so for five of them - probably a 3-5 year