Hi every one, in "line sizing" when we caclulate the item "pressure drop", for such minor losses as of valves and fittings, resistance coefficients k should be taken from tables. Howerver, i see that we can also use formula to get those k and i have some formulas for this purpose, but i cann't check the rightness of those formulas, or any one could help me to confirm from which handbooks/documents the formulas were taken.
Please find the formulas below
Valves and fittings (PNS = pipe norminal size, inch)
Formula
1. Pipe entrance
k= 0.5
2. Pipe exit
k= 1
3. Elbow 90
- Re<500000:
k =0.00476*(ln(Re))^2- 0.1574*ln(Re)*1.446+(Re/500000)^0.25*(0.01163*(ln(e/D))^2+0.2278*ln(e/D)+1.1055)
- Re>=500000:
K = 0.01163*(ln(e/D))^2+0.2278*ln(e/D)+1.3055)
4. Tee turn
k=1
5. Globe v
- PNS > 26”: k=4
- PNS<=26”: k= 10^(-0.2258*log(PNS)+0.9)
6. GATE V
- PNS > 26”: k = 0.1
- 5”< PNS <=26”: k = 10^(-0.1542*log(PNS)-0.7782)
- PNS < 5”: k = 10^(-0.2382*log(PNS)-0.7195)
7. CHECK V
- PNS >= 20”: k = 0.6
- 2” <PNS < 20: k = 10^(-0.1856*log(PNS)+0.01967)
- PNS <2”: 10^(-0.2534*log(PNS)+0.3551)
8.. BUTT V
- PNS> 22”: k= 0.3
- 6”<PNS<= 22”: k= 10^(-0.6523*log(PNS)+0.3527)
- PNS<= 6”: k= 10^(-0.2287*log(PNS)+0.02307)
9. BALL V
k=1.5
Thanks a lot.
Edited by zavtranguyen, 10 May 2021 - 10:00 PM.