Anybody Know?

[OneArm]

Anybody know where I can find or have the equation to determine the atmospheric pressure at a particular elevation, say at 5000ft, the atmospheric pressure is X psi? This may be simple, but I'm missing it.

Also, anyone know where I can find the optimum flow in a pipe given the manning value, i.e. d/D?

Finally, gotta vent:

I took the other boards practice exam this past weekend and it was horrible. If the real thing is going to be like that, lotsa luck, I'll stay an EIT forever. Ive been studying for at least six months doing 3hrs a day and 12 hrs on the weekends since January (close to 500hrs). I also cruised my EIT 8yrs out of school with no real engineering experience. Sucks.

Thanks.

 

[IlPadrino]

Finally, gotta vent:
I took the other boards practice exam this past weekend and it was horrible. If the real thing is going to be like that, lotsa luck, I'll stay an EIT forever. Ive been studying for at least six months doing 3hrs a day and 12 hrs on the weekends since January (close to 500hrs). I also cruised my EIT 8yrs out of school with no real engineering experience. Sucks.

Thanks.

Quantity doesn't make up for quality... if you've studied 500 hours and are having trouble with practice exams, I'd suggest you reexamine your study strategies. I'd think 500 hours is close to a study record!

 

[Dleg]

If you have Metcalf & Eddy, there are two equations in the back (Appendix B-2) for change in atmospheric pressure with elevation (the two are metric and english).

I'll tyr to type in the english version here:

Pb/Pa = exp[-gM(zb-za)/(gc*RT)]

P = pressure in psi

g = 32.2 ft/s^2

gc = 32.2 ft-lbm/lb-s^2

M = mole of air (on table B-1) = 28.97 lb/lb-mole

z = elevation, ft.

R = universal gas constant = 53.3 ft-lb/lb-air-degR

T = temperature in degrees R = (459.67 + degF)

 

[Casey]

Finally, gotta vent:
I took the other boards practice exam this past weekend and it was horrible. If the real thing is going to be like that, lotsa luck, I'll stay an EIT forever.

You think you have it bad? My wife is going to kill me if I don't pass!

Well, she might actually kill me before that if she catches me posting messages here when I should be studying.....

 

[IlPadrino]

Anybody know where I can find or have the equation to determine the atmospheric pressure at a particular elevation, say at 5000ft, the atmospheric pressure is X psi? This may be simple, but I'm missing it.
Also, anyone know where I can find the optimum flow in a pipe given the manning value, i.e. d/D?

For the PE exam I think you'll find CERM Appendix 18.A more than sufficient for standard atmospheric pressures.

For circular channels CERM Appendix 19.C can be very useful. Is this what you're looking for?

 

[al***vj]

I agree.