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About justin-hawaii

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    Justin PE
  • Birthday 12/16/1984

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    HVAC and Fire Protection
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  1. justin-hawaii

    Power PE Technical Study Guide by Justin Kauwale

    Thanks everyone for the review comments. I added an index and corrected some errors I found, for the October 2018 exam. I would love any suggestions on where I should go into more detail for the April 2019 exam. I already received requests to include Reliability Engineering & Measurement topics and more detail on motors and VFDs.
  2. justin-hawaii

    Free Mechanical FE Study Material

    I've recently put together some free study material for those taking the FE Mechanical Exam. It is separated by topic and focuses on the NCEES Exam Specifications. It is my hope that everyone passes! Feel free to message me should you have any questions. http://engproguides.com/fe-mechanical.html
  3. justin-hawaii

    Complex Power Current Conjugate S=VI*

    @ellen3720 The conjugate is used when you are given the power factor or power factor angle. The power factor angle tells you the phase angle difference between the voltage and current phasors. For example, if the power factor angle is 30 degrees lagging and you assume voltage has a phasor angle of 0 degrees, then the current phasor angle will be -30 degrees. This is because in a lagging power factor, the current phasor angle lags the voltage phasor angle. If the power factor angle is -30 degrees aka 30 degrees leading and you assume voltage has a phasor angle of 0 degrees, then current will have a phasor angle of +30 degrees, because the current phasor angle must lead the voltage phasor angle. If the power factor angle is not given and you are instead given the current phasor angle and the voltage phasor angle, then you can simply multiply these two phasors to get the single phase apparent power or you can multiply those two phasors and the root 3 term to get the 3 phase apparent power. In my above discussion, I am assuming line voltage and current for the references to 3-phase power.
  4. justin-hawaii

    Just finished the April 2018 PE Exam

    If the response was a little questionable with respect to the NCEES rules, then yes I deleted the response. It was a while back so I am not sure about your specific response.
  5. justin-hawaii

    Just finished the April 2018 PE Exam

    @bernie I published the results of the survey on my website. Please see the links below and scroll down to the Raw Reviews section. http://www.engproguides.com/hvacguide.html http://www.engproguides.com/thermalguide.html http://www.engproguides.com/machineguide.html -Justin
  6. justin-hawaii

    Machine Design & Materials Oct 2018

    I think that the NCEES practice exam is representative of the actual exam, see the link and excerpt below. According to the NCEES the practice exams contain questions from past exams. https://ncees.org/exams/exam-preparation-materials/ NCEES practice exams help you determine what you know—and what you don’t know—before taking the exam. NCEES practice exams Contain questions from past exams Simulate the format, style, and level of difficulty Provide solutions or feedback on performance in each topic area
  7. justin-hawaii

    HVAC Test Taking Strategy

    I know several people who have done @gomeybear's method, but with @Audi driver, P.E.'s variation. They speak very highly of this method. I also know a few people that have gone through each question in order. These people spent way too much time in the morning session on a few problems and ended up running out of time and had to guess on the last problems without even looking at the problem. They changed their method in the afternoon session after making that mistake. I think the test taking method is sound and makes sense since each question is worth the same amount.
  8. justin-hawaii

    Mistake on TFS Sample Test?

    Gotcha @ValonaBrau. Good catch, I missed where it stated "water", I just read the "head". You can email NCEES and hopefully they include it in the next errata. They updated their HVAC/R errata based on this last post, but I had to email them and it took from August 2017 til March 2018 . Here is the current errata for T&F https://ncees.org/wp-content/uploads/2016-Mec_Thermal_errata_ALL-2.pdf Current errata for HVAC/R: https://ncees.org/wp-content/uploads/2016-Mec_HVAC_errata_ALL-2.pdf
  9. justin-hawaii

    Mistake on TFS Sample Test?

    @ValonaBrau The term feet of water is used to describe the pressure created by the water elevation. In order to convert from feet of water to pressure per square inch as you have stated with the 0.433 conversion factor, you must use the density of water. For example, 1 cubic inch of water is equal to (62.4 lbs/ft3) * (1 ft3/ 1728 cubic inches) = 0.036 lbs/cubic inch Then if you have 12 of those cubic inches stacked upon each other, then you have 1 foot of water elevation. (0.036 lbs/cubic inch ) * (12 inch/ft) = 0.433 psi per foot of water So as you can see, the conversion of 60 feet of water to 26 psi is dependent on the density of water. When you have a different fluid, with a different specific gravity, you need to convert the density to the actual density of fluid. For example, 1 cubic inch of new fluid is equal to (62.4 lbs/ft3) *(0.7) * (1 ft3/ 1728 cubic inches) = 0.0253 lbs/cubic inch Then if you have 12 of those cubic inches stacked upon each other, then you have 1 foot of the new fluid. (0.0253 lbs/cubic inch ) * (12 inch/ft) = 0.3033 psi per foot of new fluid So you can use your HP equation, with PSI and GPM, but with this conversion.
  10. justin-hawaii

    autotransformer question

    Sorry but my content currently doesn't include buck and boost auto transformers. But I will add this concept into my next update.
  11. justin-hawaii

    Practice Problems Materials for Power Exam

    @Surf and Snow thank you for the feedback and glad I could be of help. Just to ditto @Szar i think you should remove that blackburn link. I am very paranoid about copyright infringement ever since that article from NCEES came out. So just watch out. https://ncees.org/ncees-reaches-settlement/ @Edu I really like these Danfoss tutorials that focus on variable speed drives. http://drives.danfoss.us/knowledge-center/training/#/
  12. justin-hawaii

    Just finished the April 2018 PE Exam

    To thermal test takers, What did you think about the thermal april 2018 test takers wishing that they studied more HVAC?
  13. justin-hawaii

    Just finished the April 2018 PE Exam

    Survey results can be found on the link below. https://docs.google.com/forms/d/12QyAkDirFa8z-Fu5w_1x9gkaJyrs1PIiSeQ6r4KzOgY/viewanalytics
  14. justin-hawaii

    Just finished the April 2018 PE Exam

    Survey results can be found on the links below. HVAC/R: https://docs.google.com/forms/d/1kvRzXbMQucabWkqN2Za-Pfs-NMJVBFOqgtEJowLhp4A/viewanalytics MDM: https://docs.google.com/forms/d/1LfplzRbt8XrP1IYwUrStlCfW4f1xOQOVGAkIAmh9g2I/viewanalytics Thermal: https://docs.google.com/forms/d/1rtoqA7WQAZxshUWFMJmoqi5zIJPZpYKzO91GM9hkLT4/viewanalytics
  15. Congratulations on making it through the PE exam! How did the exam go? What was your experience like? I know all the future exam test-takers would love to hear your thoughts on the forum and/or on the survey below. Power Survey: https://goo.gl/forms/AdwaX78voQy1Apli1 Just a friendly reminder, you cannot share the actual exam problems or solutions.