Engineer Boards

# All Activity

1. Past hour
2. ## Random Thoughts Version 2.0

Always love the first question on the OSHA medical questionnaire...Can you read (circle one): Yes / No
3. ## Critical insulation thickness

True. But assuming normal circumstances (normal values for insulation and convective film coefficient), you can almost bet that the heat transfer will decrease in this case. The critical radius for this application is most likely very small, so the new insulation will most likely increase the conduction resistance more than it decreases the convection resistance and thus the rate of heat transfer decreases.
4. ## Critical insulation thickness

Exactly. Its impossible to tell what will happen unless you specify: 1. Current thickness of insulating layer. 2. Thermal conductivity of insulating layer. 3. Convective coefficient.
5. ## Certified Construction Manager (CCM)

Lotty, Thanks for the help. Have you taken the CCM exam? If so, how did you do? Ken
6. Today
7. ## Critical insulation thickness

It will depend on the insulation conductivity and the convective heat transfer coefficient. In your case we know for sure that the resistance due to conduction will increase (due to the increase in thickness) and the resistance due to convection will decrease (due to the increase in surface area), but we can't tell for certain which change in resistance will be more. If the increase in conduction resistance is more than the decrease in convection resistance, the rate of heat transfer will decrease. If the increase in conduction resistance is less than the decrease in the convection resistance, the rate of heat transfer will increase.
8. ## Critical insulation thickness

Thanks for the feedback let assume we have Propane storage tank and there is insulation around the tank if we add 120% more insulation what happened to the heat transfer decrease or increase?
9. ## Bring Back the Lunch Thread !!!!

^^ But none of those dumplings are the soup kind.
10. ## So...it's been a while...

Hi jmbeck. Nice to see you posting again. There's a number of us old timers still here. welcome back. What have you been up to?
11. ## Transmission line design

This is the problem: "A utility company just hired you as a new lead electrical engineer. They requested you to design a new 500_MW power station and transmission line to connect Sydney to Brisbane (1083 km). The transmission line is lowered to 11 kV before entering residential area and then, is connected to a delta-wye transformer before connecting to a residential area that has 50 residential households. Determine the rating (power, voltage) and turn ratio of the transformer ." How can I know the input voltage, that is the value that the voltage assumes before being lowered to 11kV?
12. ## Critical insulation thickness

The addition of insulation makes it thicker, so the resistance due to conduction increases. But, at the same time, as you add insulation the outer surface area of the insulation increases, so the resistance due to convection decreases. So as you add insulation from zero thickness you have two competing effects: increasing conduction resistance versus decreasing convective resistance. Imagine you have a bare pipe and add a very thin layer of insulation. For very thin layers, there is actually an increase of heat transfer because the heat transfer increasing effect of the bigger surface area is greater than the heat transfer reducing (insulating) effect due to the insulation layer thickness. If you add another thin layer you make it worse, and another thin layer also makes it worse until at a certain thickness the insulating effect of the added thickness becomes dominant. After this point, adding layers contributes more to the increase the conductive resistance than it does to decrease the convective resistance. That point where this crossover occurs is the "critical insulation thickness"

14. ## Bring Back the Lunch Thread !!!!

Forget Costco, come to New Zealand: https://www.zomato.com/auckland/barilla-dumpling-balmoral/menu
15. ## So...it's been a while...

Same old spam-a-rama here, welcome back!
16. ## Critical insulation thickness

Hi all, I am confused with critical insulation thickness in MERM page 32-11 , the question how the insulation increase and decrease heat loss?
17. ## So...it's been a while...

Nice to see you again @jmbeck!
18. ## Best strategies for attacking the Seismic and Surveying exams

These are pretty broad questions. I always recommend examinees do as much research as they can on their own first, and then ask the forum any specific questions you couldn't find answers to. I'd read through the stickies and helpful threads in this forum, as well as read up on the exam at the State Board's site. I think you'll find answers to these questions and more by doing a little research. Good luck.
19. Yesterday
20. ## Forum Banning Game

Banned for not using an Oxford comma.
21. ## Forum Banning Game

Banned, because you seem not have noticed how cynical, snarky and sarcastic I have been lately.
22. ## Best strategies for attacking the Seismic and Surveying exams

I am going to take the CA Civil Specific exams this fall, I purchased Hiner book for Seismic and Mansour for Surveying, also I purchased IBC 2015 and ASCE 7-10. What is the best strategies for attacking the Seismic and Surveying exams, and is any other references should be added to those which I purchased?
23. ## Civil AM Office Hours - Videos

Hello everyone, below you will see the recordings of our free office hours for the Civil AM. There are still a few session left in the schedule. Join Dr. Mansour and get real time help. Let us help you become a Professional Engineer as soon as possible. Dr. Mansours Free Office Hours. There is no cost to you and you can attend any session. To enroll go to: www.joinwebinar.com and then enter ID: 635-147-867 (one ID for ALL free office hours). Should you have any questions please email us at names@passpe.com or info@passpe.com Dates for Office Hours 1- Civil AM: Monday’s from 6:30-9:30 PM-PT): 10/2/2017. 2- Transportation PM: Monday’s from 6:30-9:30 PM-PT: 9/25 & 10/9/2017. 3- Construction PM: Wednesday’s from 6:30-9:30 PM-PT: 10/4/2017. 4- Seismic : Wednesday’s from 6:30-7:30 PM-PT: 9/27/2017. 5- Surveying: Wednesday’s from 7:35-8:35 PM-PT: 9/27/2017. 6- Seismic & Surveying: 6:00-7:30 (Sei.), 7:35-9:00 (Surv.) PM-PT:10/14, 21, 28, 11/4/17. First Session July 17th: http://cdn.audiovideoweb.com/lnks/play/8c3fls5521/Office Hours/2017-07-17 18.32 Dr. Mansour Free Office Hours -fall 2017-1.mp4 Second Session July 31st: http://cdn.audiovideoweb.com/lnks/play/8c3fls5521/Office Hours/2017-07-31 18.37 Dr. Mansour FREE Office Hours -Fall 2017-1.mp4 Third Session August 14th: http://cdn.audiovideoweb.com/lnks/play/8c3fls5521/Office Hours/2017-08-14 18.43 Dr. Mansour Free Office Hours -fall 2017-1.mp4 Fourth Session August 28th: http://cdn.audiovideoweb.com/lnks/play/8c3fls5521/Office Hours/2017-08-28 18.36 Dr. Mansour Free Office Hours -fall 2017-1.mp4 Fifth Session September 28th: http://cdn.audiovideoweb.com/lnks/play/8c3fls5521/Office Hours/2017-09-18 18.52 Dr. Mansour Free Office Hours -fall 2017-1.mp4

Howdy.