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  1. wuddog

    R value for fabrics/tents

    Been a while since I've posted. So my hospital has erected a tent for COVID testing. The staff want it air conditioned. Any idea what the R value for waterproof fabric is? Has anyone got any tips or tricks for designing an A/C system for a tent?
  2. wuddog

    Are there appreciable efficiency gains from 480 V vs 277 V

    Thanks folks. Our main is 480 then it transforms to 277. We would bypass the transformer to achieve 480 throughout the system. Sounds like we may have an argument for going 480 based on your feedback. I appreciate the help.
  3. wuddog

    Are there appreciable efficiency gains from 480 V vs 277 V

    I am not an electrical engineer.[smile] Now that I got that out of the way, I have been asked if there is an efficiency advantage between 480V vs. 277V. Intuitively I said yes due to the lower amperage of the 480V, but I was then asked if I could prove it with numbers. At this point I am...
  4. wuddog

    BREATHING AIR CRITERIA

    So I know that NIOSH specifies Grade "D" breathing air as follows: (a) Oxygen (volume/volume) within 19.5-23.5% (b) Hydrocarbon (condensed): no more than 5 milligrams per cubic meter of air (c) Carbon monoxide (CO): no more than 10 parts per million (ppm) (d) Carbon dioxide (CO2): no more...
  5. wuddog

    STEAM LINE SIZING

    Interesting, chief. I've always found it to be the opposite. I thought it was because steam occupies more volume than water, thus the line size for steam is greater than those for condensate. Would love to hear other opinions.
  6. wuddog

    STEAM LINE SIZING

    katmar & hacksaw, thanks for your posts. After reading your posts, I re-checked my numbers and realized I made a huge error with the specific volume (used vf instead of vg). Now I realize I need 1.5" for 600 lbm/hr...if I want the flexibility to move up in flow I should probably go to 2"...
  7. wuddog

    STEAM LINE SIZING

    Hello, I have what I think is a quick question. I have a currently installed steam heat exchanger that I want to double in capacity. Per the design data I am only using 1/3 of the exchanger's capacity (U=180 but I am only using U=53 BTU/(f^2*h*F)). As I understand it, to squeeze the...
  8. wuddog

    Using a Pump Curve w/No Design Data

    I need to justify the repair of a branch of an existing well water line in our plant. We are currently running city water to the areas this failed branch supplies and have meters to provide daily use requirements. I know what it's costing me to supply city water on a daily basis to these areas...
  9. wuddog

    VACUUM CONDUCTANCE

    Thanks Ted. My only question about this is, "Do effective lengths for positive pressure lines apply to negative pressure?" My line is going to be around 5 torr (0.1 PSI). I believe things get a little different at these low pressures.
  10. wuddog

    VACUUM CONDUCTANCE

    I have been tasked with designing a vacuum pipeline that will be connected to an existing vacuum pump. This is the first time I've delved into vacuum design. I've read about the term "conductance" and understand it to be akin to resistance. However, all the info I've uncovered merely...

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