Pump head formula
Pump head formula
(OP)
Hello all,
I am new in engineering field, I was loking for a formula to find a pump head, I found one: Head=total pipe length*50% for elbows and fitting * 0.04. The last term I did not know what represent.
I know the formula for head is:V sq/ 2g.
Please, does any one can tell me what the 0.04 stand for.
Regards,
I am new in engineering field, I was loking for a formula to find a pump head, I found one: Head=total pipe length*50% for elbows and fitting * 0.04. The last term I did not know what represent.
I know the formula for head is:V sq/ 2g.
Please, does any one can tell me what the 0.04 stand for.
Regards,





RE: Pump head formula
1) Cameron Hydraulic Textbook (now offered from Flowserve) and 2) Crane Technical Paper No. 410.
Both are available online and provide the reader excellent knowledge regarding hydraulics, etc.
prudent decision in that you are questioning formulas . . . highly recommend learning the fundamentals, principles, and how to apply them in your work.
oh, v^2/2g is referred to velocity head, not just head . . .
good luck!
-pmover
RE: Pump head formula
RE: Pump head formula
delta z, ft + hv, ft = v^2/2g + hf, ft + hm, ft = Sum K * hv = TDH, ft
delta P, psi = TDH, ft/ 2.31
Using Hazen-Williams equation, hf = 10.44 * L *gpm^1.85 / (C^1.85 * Dia^4.8655)
Sum K = Specific K for each fitting * quantity of that fitting
Remember: The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
-Steve
RE: Pump head formula
He is another possibility for the reason of the factor. Since you are speaking of rules of thumb and roughly approximate figures, for water in pipes, after taking the equivalent length at 150% of the piping length in ft o/a of fittings, you multiply by 4 ft of water/100 ft of pipe or 0.04 to obtain the total pressure drop, when assuming the following flow rates:
for 3in. Sch 40 pipe, 30 m3/h
for 4in. Sch 40 pipe, 60 m3/h
for 6in. Sch 40 pipe, 180 m3/h
Flow rates that would result in about the same friction drop of 4 ft/100 ft of pipe, or 0.04. Just a thought.
RE: Pump head formula
RE: Pump head formula
bhp = (GPM x Ft. wg pump head)/(3960 x pump efficiency in decimals)
Average efficiency is 0.65 with larger pumps better (to .80)while smaller pumps lower(to .40)
pump head in ft. wg. should be larger than sum of pipe friction + static head if open circuit + velocity head + equipment pressure drop + valve pressure drop + safety allowance for pipe aging + allowance for balancing valve.
RE: Pump head formula
for this formula, and all variable details.