Problem #123 NCEES 2001

[Vel2018]

Hello everyone,

So I have this problem #123 from ncees 2001. It did an assumption of the coefficient of flow. 

And then showed a assumption check which I think was done wrong, but technically the values assumed in this particular problem won't matter since you get constant value of cf after 10^5 value of Re.

I though that in the assumption check, you should use the diameter of the orifice and the area of orifice and not the pipe. Since cf will be taken from the graph using Vo and Do values. Can someone please let me know if the NCEES solution is correctly done or if there is an error upon checking the assumption? Thank you!

 

[Vel2018]

The solution.

 

[MikeGlass1969]

I agree with you..  They should have checked the Re for the orifice rather than the pipe.

I tried searching the internet for an errata for this book but have not found it.

Nice find!

 

[Vel2018]

I agree with you..  They should have checked the Re for the orifice rather than the pipe.

I tried searching the internet for an errata for this book but have not found it.

Nice find!

Also the area used was (5/12) which is wrong. Should be 0.4175/12. If this type of problem requires more accuracy, it could have gone wrong.

Yes, its is indeed nice, got about 50 different problems from 2016 version. Bought it as soon as I saw one for sale on ebay.

 

[MikeGlass1969]

I do agree with the (5/12)....  thats diameter of the orifice, 5 in divided by 12 in/ft....  the are using the form pi*d^2/4 for the area.

Why do you think .4175?  The diameter ratio is .5...  

 

[Vel2018]

I do agree with the (5/12)....  thats diameter of the orifice, 5 in divided by 12 in/ft....  the are using the form pi*d^2/4 for the area.

Why do you think .4175?  The diameter ratio is .5...  

Oh yes, that's right. I was going straight to d=0.4175 ft. My bad. I just got the impression it did directly from 10in x 0.5 = 5. But upon checking on pipe schedule it was actually correct should be 5.01/12 to be accurate.