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  1. timsch

    Scale consideration with ultrasonic wall thickness testing

    3rd party inspection service has done the measurements.
  2. timsch

    Scale consideration with ultrasonic wall thickness testing

    We will test it to 1.5 times its MAOP. I will keep your other recommendations in mind. Thanks for the responses - much appreciated.
  3. timsch

    Scale consideration with ultrasonic wall thickness testing

    We're taking 4 measurements @ 90deg every 3 feet, totaling 168 points (chambers are actually over 100' long). Statistically, I think we should be fairly confident that we have a pretty good picture, but I agree that we likely don't have the absolute minimum thickness. My calculations are...
  4. timsch

    Scale consideration with ultrasonic wall thickness testing

    Thanks for the response. We're measuring from the outside.
  5. timsch

    Scale consideration with ultrasonic wall thickness testing

    I'm running calculations to re-rate our carbon steel hydrotest chambers. I have UT wall thickness measurements. These chambers are very long (4 to 5" pipe, 100' long), so any scale that might be on the ID of the chambers was not removed. Would scale throw off the measurements, or would the...
  6. timsch

    RTD temperature elements - heavier extension wire gauge effects?

    For high calibration temperatures, the reading is low, for low calibration temperatures, the reading is high. The further from ambient temperature, the greater the deviation, which supports the thermal conduction along the wire hypothesis. Moisture in the MgO is always on our minds...
  7. timsch

    RTD temperature elements - heavier extension wire gauge effects?

    I agree. That's been my hypothesis. We had issues calibrating at -196C, being off by 5-8C when 1' of wire was immersed. When we immersed the majority of the wire, we were much closer. The further from ambient we've been, the greater the error, and the error has been to the ambient side of...
  8. timsch

    RTD temperature elements - heavier extension wire gauge effects?

    3-wire with a PT100 wire-wound ceramic element
  9. timsch

    RTD temperature elements - heavier extension wire gauge effects?

    We use Class A resistors by default in our applications. With our typical 22-26ga extension wire, we rarely have problems meeting class A tolerances and never fall outside class B, with this wire we are having difficulty with class A half the time and are even falling outside of class B...
  10. timsch

    RTD temperature elements - heavier extension wire gauge effects?

    Does anyone have experience with RTD elements that use heavier gauge extension wire than that which is typically used? I have an application where customer has specified 18 gauge wire where our standard is 22-26 gauge wire. We are having more difficulty with calibration than we typically do...
  11. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    Thank you everyone for the input. It's been a good education for me, and is much appreciated.
  12. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    I accidentally hit like when I meant to hit reply. I actually don't like it. While it may be true looking at it from a bean counter perspective, it is a learning opportunity for an engineer. It's been a good use of my time learning about a discipline I had no experience with that hopefully...
  13. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    Ours is an R&D facility. This is a full scale furnace as used in refineries. Roughly 10 x 8 x 15 ft^3 in the radiant section, which is where we've tapped through the roof for this particular test. The 1-1/2" pipe is part of a test piece only. I mentioned earlier that there is a slight...
  14. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    I was not looking at the curve correctly. Now I understand that the no-flow condition is at a dead-head condition, and maximum flow at roughly ambient happens because there is no resistance to the flow. Thank you. Yes, this curve is not quite accurate for our conditions. From the...
  15. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    I apologize if I've misled anyone with wrong terminology. After seeing the drawing, does that change anything with the calculations you've given?
  16. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    Here's a drawing of the exhauster itself. The bottom flange is what I blanked off measured the vacuum in a separate test run. The air compressor line was input on the left side flange connection. What is not shown is the length of pipe used during our R&D tests that connects to the bottom...
  17. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    I appreciate the responses, but I think that I've not been clear enough about my conditions. Sorry for any confusion. "The suction is the lower section of the tee you refer to which sucks in the exhaust gas into the venturi section and has nothing to do with the main flow pipe." It is this...
  18. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    I've already measured the vacuum resulting from the flow through the venturi. I should be able to leave the venturi out of it and treat it as simple air flow through a section of pipe with a pressure differential between the ends. It'd be nice to have the hot-wire anemometer, but it was a...
  19. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    Thanks for the replay. I do have a table (attached) from the manufacturer, but it is greek to me. The suction pressure on the Y-axis tops out at 15.5 psia, which I assume is near full vacuum since the maximum suction capacity is at that value. My suction pressure is much lower than that, if...
  20. timsch

    Trying to determine airflow through a pipe when vacuum is applied

    Hello All. Non-piping engineer here. I am trying to determine what airflow I have through a section of pipe attached to what we call an exhauster. Searching for exhausters online doesn't come up with much, so I don't know how common they are or if they're known by some other term. Our...

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