Recent content by sheela34

Regarding #78, technically all the answer choices would meet the requirement of having a deflection of less than 0.5 in., but I guess they want the answer closet to the cutoff spring constant. Though the question doesn't make it absolutely clear.

I was confused about the superheat as well. Glad others also think it is unclear. Though I included superheat in the evaporator discharge enthalpy, the answer I got is still closest to the correct answer. Yout reasoning to focus on the table provided also makes sense but now we are out of the...

Regarding #52, I don't understand why they included heat pump power in the answer when the question is just asking for the value of the supplemental electric heat. Regarding #54, this one I did not comprehend at all what the situation is that is presented in the problem. oh well

Personal opinion, #39 seems to be written poorly.

Regarding #38, if water pump inlet pressure is 20 psig, and discharges 160 ft above to atmosphere with 20 ft of friction losses. Isn't the pressure required after the pump 160 ft + 20 ft = 180 ft / 2.307 = 78 psig? I'm not sure why the solution adds 20 psig to that...

Regarding a different question, I'm looking at #25 in the practice exam. Although the the numbers are plugged into the correct equation, I believe the equation shown on the 1st and 2nd lines switch the CFM1 and CFM2.

How does the equation go from the first one to the next one?

What is the difference between using one or the other equation to calculate the NPSHA?

No worries, I have also ordered supplementary CBT style practice problem books that I will go through.

Yeah...I was like why try to read this chart when there is a table. This is from the 11th edition of the PPI Mechanical Reference Manual (2001). Bit old since it was passed down to me, but I figured most engineering concepts probably didn't change in the last couple decades. I recently borrowed...

Oh nice, do you know if we can move drawn lines around? Because that would help with the SHR.

Good to know actually answer choices won't be that close. The question was to find the enthalpy of air at Tdb = 80F and Twb = 67F. The choices were: - 30.2 btu/lbm - 30.8 btu/lbm - 31.5 btu/lbm - 31.9 btu/lbm So...1-2% difference in the answers of this practice problem.

Also wondering if they provide a hard copy of the psychrometric charts for the CBT exam because matching multiple lines up on a display ain't easy...

So, I'm wondering at what RH the density in this table 1.2.1 Properties of Air at Atmospheric Pressure is tabulated at since it didn't match specific volume values in ASHRAE Psychrometric Chart No. 1 - Sea Level. Since that margin of error did affect the correct answer on some practice problems...

thank you! didn't realize there was a new version out