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Slay the P.E.

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Everything posted by Slay the P.E.

  1. Thanks for the shout out. We’re glad to have been of service in your studies. Congrats!!!
  2. Thanks!! Much appreciated. Congratulations!!
  3. Thank you for creating this thread. 😊
  4. If coach woulda put me in 4th quarter we would’ve been state champions. No doubt.
  5. 'Till Spam do us part. Couple has SPAM-themed wedding
  6. I know how this spam thread influences the release date
  7. Let me tell you how getting to 15k posts is related to the results release date:
  8. LOL. No. I'm afraid not. There are like 6 or 7 problems in this thread. Did you work them all?
  9. Be mindful of the issues that are being reported with that manual. Most have been for TFS but it seems reasonable to suspect the MDM and HVAC sections might be affected too.
  10. The link doesn't work because one has to be logged in to myNCEES to download the manual. I'm going to urge HVAC people to download and review this ASAP. It should put to rest any doubt about what ASHRAE handbooks to bring to the test. Here NCEES has copied everything they deem important. You should review the Refrigeration, HVAC, and Combustion sections and make sure you understand how to use every table and graph in those sections. They're virtually all taken straight from the ASHRAE handbooks. Similarly for MDM. This handbook definitely helps determine which areas of Shigley's you should really emphasize in your prep. After a quick review with an eye for the TFS Exam: YIKES! no Mollier diagram anywhere in sight. Makes steam turbine problems unnecessarily long. There are no Normal Shock compressible flow tables, but they do provide the equations, so people taking CBT will have to solve shockwave problems without the benefit of the table. That's not nice of them. Their table of unit conversions is appallingly sparse. The psychrometric charts are preposterously blurry, bordering on unreadable.
  11. If "B" is a reservoir, then VB = 0, so that's the first thing you're doing wrong. Also, when you write the Bernoulli equation from A to B, then hf has to be from A to B. From what you wrote above, your hf is only from A to the end of branch 1. So, yes, you need to add the friction loss across either one of the other branches. This is what they did in the link you provided.
  12. How did you solve for V1 if you don't have hf for branch 1?
  13. Can you show your work? The approach you're describing here is exactly what they did in the link to solve the problem.
  14. Yes, tables usually give a range and also a "design" value (See Appendix 17.A in page A-48 of MERM13. I'm not sure what the "PE Handbook" that you're referencing is, but in MERM13, the Moody Diagram of page 17-7 doesn't have a table). But anyway, you're right. Values are typically listed as ranges. So, what to do? Let's look at the problems in the Thermal and Fluid Systems practice exam from NCEES that use a friction factor or a friction head loss: Problem 126: They say "smooth pipe" but they also just give you the friction head, so no need to calculate the Darcy friction factor. Problem 133: You're asked to calculate the friction head loss, but you don't have enough info to use the Darcy equation. You find hf from the definition of NPSH. So no need to calculate the Darcy friction factor. Problem 505: The friction factor is given in the problem statement, so there's no need to calculate the Darcy friction factor. Problem 515: The friction loss is given, so there's no need to calculate the Darcy friction factor. Problem 519: The friction factor is given in the problem statement, so there's no need to calculate the Darcy friction factor. I notice a pattern. I suspect that most likely you won't need to calculate a friction factor with a Moody chart in the test. HOWEVER, if you do, I strongly suspect they will tell you exactly which roughness e to use because given the ambiguity in the ranges, you will not land on the correct multiple-choice answer unless you use their same roughness. Finally, if push comes to shove and you find yourself having to calculate a friction factor and they are not explicitly giving you a roughness in the problem statement then the safest bet is to use the "design" value from Appendix 17.A
  15. They're taking Environmental Engineering exam, per their profile.
  16. It's exactly the same one you posted from the solution in your book. The one with the difference of the square roots of the heights.
  17. The equation you attempted to use is for steady state, which is achieved only when: the fluid being drained is replenished at the same rate at which it is leaving through the orifice, or the volume of fluid in the tank is so large that one assumes the water level remains constant during the period of interest. Neither one of the above apply for the problem you posted. In that problem, you have a transient effect, and there is no other way to solve it other than considering time-dependent effects. The equation they used in the solution is derived in page 17-19 of the MERM13 and it is equation 17.83. It is a time-dependent solution.
  18. Don’t know if people are aware of this thread. We won’t be adding more problems to it, but all problems here are still very relevant.
  19. We won't be adding any more problems to the "practice problem of the week" threads. However, the threads are still here in the boards and are relevant, not just because of the problems themselves but also because of the lively discussion.
  20. Thanks! buying our books is the best way to prepare to tackle it wink, wink, nod, nod.
  21. This problem appears in our Fluid Mechanics & Hydraulics book. Here's the solution from the book. Let me know if you have any questions. Thanks,
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