In the 2020 questions, you use the constant 776 in this question but it is not used in either the NCEES or the FPH.
Which method is correct?
This issue has been confusing to me for a while, according to the calcs below on Meyerfire Prep 2019, it looks that Lumens = cd, I doubt this is correct.
If I search the internet, there are should have a factor, which is the solid angle.
Cd = lumens/ sr
From Wikipedia I found that E is Illuminance which is in lumens/m^2 which is the incident flux on a surface, as in the problem. One lumen per square meter is a Lux.
Are the units on this correct?
Problem 183: For the final step, “Volumetric Flow Rate of Smoke,” the unit obtained as you show would be ft^3/s. So, in order to obtain the final answer in CFM, the value in ft^3/s should be multiplied by 60 in order to convert to ft^3/min, or CFM.
Is this valid?
VN: For Problem 122, I wanted to check if I was breaking down the solution properly. I'm not seeing the end solution of EH1 in NFPA 13 Table 13.2.1.
Could you take a look at the assumptions below and let me know if I'm missing something or assuming the incorrect storage configuration?
Below is the information extracted from the problem statement:
synthetic fiber (less than 50/50) - Class III (NFPA 13 Table A.5.6.3)
natural fiber clothing - Class III (NFPA 13 Table A.5.6.3)
rayon - Class IV (NFPA 13 Table A.5.6.3)
Since movable racks, treat as multiple row rack storage. Storage directly on shelves more than 50% open, so exposed storage. Storage height 10'6".
Assuming unexpanded plastics as the worst case, I'm ending up at either OH2 or EH2 depending on max ceiling height which isn't specified in the problem.
BM: Looking for clarification on problem 151. Why do you use the full length of the room (12.8m) when the strobe is centered on that wall (6.4m)? Wouldn’t this make the farther distance for the sound to travel be the 9.2m? Yielding answer b, 34cd?
JD: Can you explain the logic used in determining the answer to Question 52 – I am having a hard time understanding why a central station would not be correct or is less correct that the Proprietary Supervising Station?
JM: For number 1 - is this something we would be expected to know? The NCEES handbook doesn't provide this equation for calculating convective heat transfer coefficient.
From Joe: Yes, it's actually in NCEES 3.3.2 although I didn't have that referenced there.
JM: Quick follow up question on 1. In NCEES section 3.3.2, the equations to solve for "h" aren't available.
JM: For number 9 - would option c also be correct? NFPA 13 states that K-16.8 uprights are acceptable, but doesn't list pendants as being acceptable.
JG: Please see question #8 of week 16 attached and the reference from page 16-102 of the 20th edition of the Fire Protection Handbook, listing dormitories under the NFPA 13D standard. What are your thoughts?
JG: Please see my question and solution attached. The question references space which infers the quantity of agent. It does not ask for concentration. Based on concentration the solution is correct. But by assuming an ambient temp of 70 degree F, the ranking order would be differ from the solution. Which is related to space/quantity of agent, what the question asks. Am I missing something?
What are your thoughts?
TH: I just wanted to check with you about this question. Isn't the quantity of agent also dependent on the specific volume of the agent? That lead me to put the answers I had after reviewing the Table A.5.5.1 and Table A.5.5.2 volume requirements. I checked for varying temps (70F and 10F) and still ended up with the same order I input in the screenshot below.
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