Making-over of our Opti-Temp

So hopefully as some of you may know from my previous post, the Opti-temp pump is not powerful enough to handle our monstrous diffusion pump piping lines. The only solution that seems to make sense the most was to cut the pipings in half and upgrade the current 0.3 horsepower motor to a 0.5 horsepower motor. By doing this, I expect to go well above the suggest minimum flow rate of 3.0 gpm specified in the diffusion pump spec list. Currently, I can only reach 2.3 gpm at a reliable steady state.

The motor was ordered two weeks ago and it was only few days ago when I finally saw my new half-horsepower motor on my desk! At the moment I saw it, I just rushed to the basement laboratory with it as fast as I can with all those childish hopes and dreams! Now it's time to give some makeover to our troublemaker!


The above picture shows the current 0.3 horsepower electric motor. I opened up the electric compartment so that all the internal wirings are visible. It's quite simple. + phase, - phase, and ground. Beautiful.


In case some of you are wondering why the hell a piece of tissue wrapped under a sheet of aluminum foil is sitting there in the background, it was for housing thermocouple. But why tissue? Since there is a huge bypass of air flow around the motor, the convection effect tended to degrade the quality of thermocouple measurement of motor surface temperature. So I had to insulate it from the turbulent air flow.


Now, before I actually hook things up, I took my last picture here, this time, the 0.5 horsepower motor and the 0.3 horsepower motor side-by-side. My pretty thermocouple wrap is still posing in the background! In terms of the size they are not very different although the above picture kind of magnified the size of half horsepower motor since I was shooing the picture from a right-side angle. 

In our lab, we have a tenth of a million dollar beam wavelength shifter, state-of-the-art femtosecond pulse laser machine, and all those fancy crystals for optics which easily go over four grands for something as tiny as a fingernail, but we do not have a simple female hex wrench which means that there is no way to take the screws out to decouple the wires to motor! How sad is this?

At the time, I had to change the motor as soon as possible since I am a kind of person who just cannot wait for stuffs once everything is there, so what the heck, just cut-off all the wires, so I did.

Cutting-off wires left me only a tiny fraction of the length to work with for which I had to make an extension by soldering some extension wires. Eventually the motor was hooked up taking a total of roughly 5 hours of labor. You may wonder why it took me so long. This is because the space around the pump is restricted by the awkward placement of a mechanical pump used to back up the diffusion pump. All in all, I had to squeeze myself into about a 40cm by 1m (1.3 ft by 3.1 ft) narrow rectangular space gap and awkwardly position myself to access the internals of the pump system. Being skinny sometimes proves itself useful in situations like this.

In addition to this difficulties, I did not want to unhook the pipings, electric wireings inside the system while doing this task. I know this sounds absurd and rather dangerous but you know, people tend to role their own way and I guess this is how I role. Therefore, working with all the internal systems intact added more difficulties in placing motor in position since working space is highly constricted. Placing the motor in a right position took hoping 2 hours.


With my fingers crossed, I turned on the pump. Good god, no wiring mistakes as there was no typical blow up of things followed by smokes and awesome vibrations. The motor seemed to handle a maximum of 3.3 gpm flow rate okay. This is a significant increase over the previous motor. Now we can finally trust this thing and hopefully this baby will continuously run without any problem. The pump is currently up and running for more than 24 hours and I plan to let it run for more than at least three days to make sure that it is good and reliable.

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