Monday, 27 June 2011

My KH228 solder paste dispenser - Part 2 (Alternative pressure sources)

I have an air compressor - but it is big, heavy, noisy and most importantly - located no where near my workshop. I don't really want to have to move the compressor, and I'm not sure if I want to buy another one just yet. Lets try another way:


 Air duster! Its not really air but compressed hydrocarbon (or similar) gasses (this is also why they last so long) so you need to take a couple of precautions.
  • Use only non-flammable dusters - check the label (I have no idea about the one above, it's not available in Australia!)
  • Use in a well ventilated area - you could suffocate!
  • Take a few deep breaths of fresh air and even cough every so often to clear your lungs as this stuff is supposed to be heavier than air and could be hard to clear from your lungs.
I did a bit of googling and found that most of these cans provide pressure in the 80-85 PSI region - plenty for my purposes. One problem left - conencting up the can!


A quick jig built out of some scraps and we can test! The can nozzle was screwed to the metal bracket on top, it was then heated and the hose barb was then screwed in to the malleable hot plastic - completely leak free.

The entire setup


And it works!




8 comments:

  1. Are you worried about the pressure dropping off as the can empties? I guess as long as there is liquid hydrocarbon left, your pressure will remain moderately stable- but I wonder how long that will be. How low is the pressure regulated down to? I wonder if another, longer-term solution might be one of these:
    http://www.harborfreight.com/11-gallon-portable-air-tank-65595.html
    Also, compressors for airbrushing are very quiet. If you want to drop some cash on it, a paintball CO2 tank with a regulator would also work well.

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  2. As long as there is some liquid and some gas hydrocarbon, the pressure will remain constant assuming equilibrium is reached sufficiently quickly (almost certainly a fair assumption here as you're probably not using much at a time), and as long as the temperature is constant (probably stays close enough)

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  3. I believe you are right, the pressure should be stable until it is so low that there is no liquified gas in the can. The dispenser has a gauge which will show when the pressure gets low, I have it's regulator dialed down to around 50 psi and it still works with tiny nozzles. How long will it last? I'll have to let you know. I do loosen the wing nuts to stop the can when it's not in use. The portable tank is a great idea, I might pick one of them up when I burn through a can or two!

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  4. You could just rent a "High Pressure Air" tank a.k.a Scuba tank or a C02 tank and get a regulator. Or what I did was run a compressed air hose through the house and left my compressor in a area that reduced the sound.

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  5. Renting isn't a good solution and compressor is way to far to run an air hose - If I am going to buy another compressor it will be on the outside of my lab with the hose running in for sure. This was more of a test to see if it works and to get a bit of hands on time with the dispenser before buying another compressor.

    I like the comments on H.A.D. about using a refrigeration compressor, i'll definitely see if I can find an old fridge to cut one out of and play with.

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  6. Or use one of those cheap 12V compressors available at supercheap auto?

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  7. Noisy as hell - still need a surge tank, pressure switch, several amps at 12v.....

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  8. Umm... If you go to an art supply house, you can find much larger versions of your canned air which are sold for the sole purpose of running an air brush. They even sell all of the hardware necessary to interface the can to a hose.

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