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Recent content by NZBen

  1. NZBen

    Large diameter pipe with small extruder?

    I'm wanting to make some long lengths of large diameter pipe around 450mm dia with a 28mm wall. I only have a small extruder and the die making company says it's not possible. My extruder has a motor of 10hp and I'm not sure of the output capacity, but am assuming close to 100kg/hr. I'm...
  2. NZBen

    Super Hydrophobic Spray ON?

    Hi Chris, thanks for that, I have a small vile of Octadecyltrichlorosilane so I guess Alcohol is not the best. I'll have a look around for hexane? I'm quite excited and cant wait to have a play with it. Any thing specific to look out for when handling/mixing/applying? Thanks again
  3. NZBen

    Super Hydrophobic Spray ON?

    Hi Chris, thanks for all your informative posts, you say with the silanes you use a hydrocarbon solvent like heptane or hexane - would an alcohol like methanol work as a solvent also? Thanks Ben
  4. NZBen

    Oversized extruder????

    I realize that a 10hp is a very small extruder by industrial standards, however the profile I'm wanting to extrude is really tiny. I'm only estimating that 25kg an hour is the throughput, but may be off by several factors. So I was wondering if running a machine at several times (around 50...
  5. NZBen

    Oversized extruder????

    I want to trial a prototype extrusion from polyprop, I'm only semi familiar with the extrusion process and have never officially operated a machine. I'm currently building up a die and I have managed to pick up a hardly used extruder from a university for a song. However I'm starting to be...
  6. NZBen

    How to create high vacuum cheaply - maybe?

    I meant to say water vapor pressure AT LIQUID NITROGEN TEMPERATURE is around 1e10-19Pa
  7. NZBen

    How to create high vacuum cheaply - maybe?

    The vapor pressure graph was my inspiration, if you look at the vapor pressure chart for water at liquid nitrogen temperatures, the pressure is far lower than any standard vacuum pump could achieve. Ie may vacuum pump can go to I think 1.3e10-2Pa where as water vapor pressure is somewhere...
  8. NZBen

    How to create high vacuum cheaply - maybe?

    Thanks for your input so far guys, I'll give it a go and see what happens. rmw, am wondering how will the water limit ability to pull down into deeper vacuums? The water vapor is what's going to be 'producing' the vacuum?
  9. NZBen

    How to create high vacuum cheaply - maybe?

    I'm wanting to generate a vacuum for purpose of making an LN2 dewar. I'd rather not buy a turbo molecular pump or diffusion pump if I dont have to. I've mentioned the idea to a couple of people who've thought it's dumb and wont work, but thought I'd try and get a vote here. I have a 2 stage...
  10. NZBen

    Simple pressure/temp eq

    Thanks latex man, so does the air warm back up when it slows down? is it only at that temp at the nozzle tip? How far off would a thin section hole be? -60 degrees? I just have this stream of high pressure low temp air in large volumes and want to get as much cooling capacity that I can from...
  11. NZBen

    Simple pressure/temp eq

    I've just done some more research and found that the temp drop is negligable if the airflow is not moving fast - so would I get more cold air out of a vortex tube or a turbine? How cold could i get it? With 2.5MPa and initial temp of -30C
  12. NZBen

    Simple pressure/temp eq

    I'm trying to figure out the temperature of air when it expands out of an orifice I have air at -30deg C and 2.5MPa, what temperature will it be when it expands to atmosphere? I presume if I can run it past a turbine it will become even cooler. The only equations I have - also take volume into...
  13. NZBen

    liquid CO2 injector for dry ice machine (how does it work)

    Thanks Montemayor - the reason I'm curious about these machines is that they are what my competitors are running (funnily enough the one shown in the pic does have an asco revert recovery machine hooked upto it) being that they are my competitiors machines I wanted to know their short comings...
  14. NZBen

    liquid CO2 injector for dry ice machine (how does it work)

    Maybe no one knows the mysteries that lie beneath the theory of the spiral tube/ejector/exchanger device I got a theory but not too sure how true it is (and i've not really had much time to look at it so I'm prolly way off track) - my theory is that the liquid CO2 begins to spiral around the...
  15. NZBen

    liquid CO2 injector for dry ice machine (how does it work)

    I have my own system which works well, but I was wanting to know how this other system works it looks more complex than mine and was thinking there might be some cleverness to it - solely relating to the snow formation not the machine itself (my machine is a fully stainless hydraulic machine)...
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