Scanning Electron Microscope Cooler
This drawing shows my plan for a circulating cooler to supply cooling
water to the scanning electron microscope's diffusion pump. A 3.5
gallon plastic pail will hold the circulating pump (National Garden Wholesale
ECO 264 submersible pump, product number 728305) and serve as the water
reservoir. The lid of the pail will support an ~ 50' coil of 3/8"
OD, 0.035" wall, aluminum tubing and a 4" muffin fan (probably older than
the SEM, a Sentinel Model 747, manufactured by Rotron Mfg. Co., Woodstock,
NY). The coil will be supported by four sets (two shown) of 3/8"
long by 1/2" OD nylon spacers and 1" OD by 3/64" thick 18-8 stainless steel
washers strung on lengths of 1/4"-20 18-8 SS threaded rod. The fan
will be supported on an 8 3/4" circle of 1/4" thick polycarbonate.
Flexible PVC tubing will connect the circulating pump to the water inlet
of the diffusion pump and return the warm water from the diff pump to the
top of the coil. The muffin fan will pull air through the 3/32" gap
between the tubes of the coil, cooling the water and exhausting warm air.
The bottom of the coil will be directed back into the pail, returning the
cooled water to the reservoir.
Here's a picture of the parts, ready for some assembly. The aluminum
tubing was coiled around an 8" OD form.
A view of the components assembled.
And a different view, including the pail.
Here are the connections to the diffusion pump (getting a bit crowded).
And another view of the installed cooler. I was originally thinking
of mounting this on the instrument frame, but the pump and fan do produce
some mild vibration, so I'll leave it on the floor until I get around to
Overall, that was about eight days from when I sketched out a rough
drawing of the cooler to when it was installed (and posted here).
(And it should be noted, two of those days were spent with visiting relatives
[Labor Day weekend] and it took another two days for parts to arrive [except
for the pump and fan, the parts came from McMaster-Carr].)