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Recent content by Orionstar

  1. Orionstar

    Gear Center Distance Variation

    I would like to use a pair of equal diameter spur gears to connect opposing friction drive rolls ("pinch rolls"). The hardened steel rolls will be about 3 inches in diameter (I can specify this) and the strip will be between .035 and .058 inches thick, therefore the center distance will need to...
  2. Orionstar

    Pump for circulating hot Limonene liquid

    To close this out, as the OP, we never did build this job (for other reasons). We had settled on using a March mag drive pvdf pump with the vessel at -2.5psig. With a discharge throttle valve we expected to have a positive discharge pressure (we only needed 1/3 of the wide open flow rate) so...
  3. Orionstar

    Fittings for tubing under low pressure (vacuum)

    Thanks for the comment. The tubing, at different times, will see 60-80C fluid (similar to water in viscosity and density) at pressures between -7 and + 15 psig, and 80C vapor at pressures as low as 50 Torr (absolute). Oh, by the way, diameter is in the 1/2" range for the most part. I don't think...
  4. Orionstar

    Fittings for tubing under low pressure (vacuum)

    Does anyone know if there is a flexible polymer tubing (in the 1/2" OD range) that can handle fluid flow inside at 80C under 27" Hg vacuum (about 50 Torr). If so, how to connect it (metal compression fitting, flared, barbed)? Most charts I see give vacuum ratings at 72F. Also, don't know the...
  5. Orionstar

    Pump for circulating hot Limonene liquid

    I spoke at more length with Iwaki. Turns out the negative pressure worry is due to the thin plastic shell that separates the impeller magnet (in fluid) from the outer motor magnet. With enough negative pressure in this area, the shell can deform inward and rub on rotating impeller magnet. We...
  6. Orionstar

    Diaphragm Vacuum Pump Ratings

    I do understand the physics and I'm saying what your saying. I guess I didn't write it well, but if you re-read what I said, the mmHg will become higher (like you said in your example of 150 mmHg). Yes, that is a "lower vacuum" (higher abs pressure). I agree totally with your explanation of the...
  7. Orionstar

    Diaphragm Vacuum Pump Ratings

    Compositepro - so you agree with me that it is highly unlikely that the max vacuum rating of a diaphragm pump (this one is published as 70 mmHg) won't change (become a higher number mmHg) if the pump output is into a 15 psig tank vs atmosphere?
  8. Orionstar

    Diaphragm Vacuum Pump Ratings

    I have questions relating to a diaphragm vacuum pump. I am looking for a diaphragm vacuum pump that can pull down a tank to between 50 and 100 Torr and at the same time push the outlet to another tank sitting at 15 psig. I see some pumps that have ratings for both max vacuum inlet and max...
  9. Orionstar

    Pump for circulating hot Limonene liquid

    Thanks for the info mm. A mixer or propeller is off the table at this time. Also, there is no air available for an air diaphragm pump. Good news is the process vacuum requirement is much reduced - now we will probably run the vessel at around 300 mmHg. Also, the flow requirement might be as low...
  10. Orionstar

    Pump for circulating hot Limonene liquid

    Thanks for the replies so far. I can place the pump as far as about 2 ft below the vessel bottom. I guess that will get me a little static head for the pump inlet. I don't have air available for an air-diaphragm pump, but maybe slow motor driven diaphragm? How about an oversized vane pump run at...
  11. Orionstar

    Pump for circulating hot Limonene liquid

    I need to find a pump that will circulate hot Limonene to create flow within a heated vessel. The Limonene will be at 80C and in a vessel that has been pumped down to 1 psia. It will be just under it's boiling point (VP at 80C is just over 1 psi. Properties of Limonene are; Sg .84, 0.9 Cp (at...
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