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  • Users: Roach
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  1. Roach

    Metric????

    Sorry for the dumb question, but the answer isnt as easy to find as you might think..... Can someone tell me the standard units for airflow in metric correlating to CFM? M^3/sec, M^3/min???? What about water flow? L/s? Thanks
  2. Roach

    ELECTRO GALVANIC?

    IT IS COMMON TO HAVE A DI-ELECTRIC UNION ON COPPER TO STEEL PIPE CONNECTIONS. IS THIS NECESSARY FOR DUCT CONNECTIONS AS WELL? MY UNDERSTANDING IS THAT THE WATER IS THE CATALYST FOR THE CORROSION, BUT CAN MOISTURE LADEN AIR PRODUCE SIMILAR RESULTS (I.E. COMMERCIAL DISHWASHER EXHAUST?)
  3. Roach

    electric motor heat gains

    ASHRAE Fundamentals has a chart that says that an electric motor driving a fan generates as much heat as the the total power rating of the motor plus the inefficiency of the motor (assuming the fan and the motor are both in the conditioned space). This seems to negate the energy balance that...
  4. Roach

    Industrial Oven Requirements

    Does anyone have any suggestions on the proper fire prot. system for an industrial cure oven for a paint line? (Can't find anything specific in NFPA, please direct) This is a fairly large building with ovens on the mezzanine and is not fully sprinklered currently. thanks0
  5. Roach

    LMTD manipulation

    I have an existing shell and tube HX with the following design values: 190 GPM both sides Hot inlet 220ºF Hot out 200ºF Cold in 165ºF Hot out 185ºF I want my cold in and out to be 140 and 160ºF This increases my LMTD from 31 to 48 (includes correction factor for hybrid design). At the design...
  6. Roach

    Pressure Blower with restricted intake

    I have a pressure blower with a restricted intake. When I open the intake fully (no restriction) my motor pulls FLA (I have blown fuses). When I close it (restrict air flow) it goes down to idle (normal amperage on the motor). I would think that restriction to intake causes the motor to work...
  7. Roach

    Shielded cable grounding

    Can someone explain why if I ground both ends of a shielded cable carrying DC signals in a wireway with AC current carrying wires, I get noise, but if I ground just one end, I don't? Thanks
  8. Roach

    Synchronizing Cylinders

    I need to synchronize 2 pneumatic cylinders stroking in the same direction about 7 feet apart. Rack and pinion would be great if they were stroking in opposition, but they are in the same direction. Are there any valves, or mechanical concepts that can be applied to allow synchronzed stroke of...
  9. Roach

    MASSPROP

    How do I specify the material or density of a solid so that when I get mass prop. I have an actual mass. Right now I get the same mass as I do volume b/c it defaults to a density of 1, I asssume. Where can I change this? Thanks
  10. Roach

    3D and 2D together

    is there a way for me to create a layout with a 2D drawing with dimensions, and paste a 3D of the assembly in an isometric view for visual aid? Thanks
  11. Roach

    Discharge Head

    If I have a dischrge line from my pump that runs up vertically to 102" (elevation), horizontally 60", and then back down to 58" (elevation) to dump at atmosheric pressure, is the discharge head 102" minus friction, or 58" minus friction? I am wondering if a siphon affect...
  12. Roach

    Freezing Temp of Glycerin?

    Can someone help me? I need to know the temperature at which glycerin and ammonia freezes, and I can't seem to find this info in my books. Thanks, Roach
  13. Roach

    What is TDH?

    If I have a guage at the outlet of my pump on a closed H2O system, and it reads 42psi with the pump on, and when the pump is turned off it reads 28psi, does that mean that I am getting the GPM that is seen on the pump curve at 42 or 42-28=14psi ( 97 or 32 ft of head)? If it is 97, then can...
  14. Roach

    High Temp Exhuast Fan

    In a high temp exhuast fan (i.e. 15-1600ºF), do you mount the floating bearing on the fan side or the sheave(drive) side? Does the shaft grow towards or away from the heat? If I mount the floating on the sheave side, I am compromising belt life because of sheave alignment? Is this correct?

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