Size of line for CNG slow fill
Size of line for CNG slow fill
I am in the process of installing a CNG station for my company vehicles. Maximum compressor output is 116 cft/min pressure at compressor is 3600 psi distance from compressor to final slow fill post is 325 ft size of line from compressor to slow fill posts is 3/8" according to the calculator pressure drop at end of line would be 25 psi at maximum flow which would be acceptable is this correct or should i use 1/2 line? Thanks in advance for your help
Re: Size of line for CNG slow fill
You should have enough flow with 3/8".
Here is the calculation report that I have with isothermal gas flow rate calculator at:
http://www.pipeflowcalculations.com/gasflow/
Isothermal gas flow rate amd pressure drop calculator
1. volumetric flow rate at normal conditions (qn):
qn : 116 ft3/min
2. mass flow rate (w):
w : 140.91876 kg/h
3. length (L):
L : 325 ft
4. diameter (D):
D : 0.375 in
5. pipe roughness (kr):
kr : 0.01 mm
6. local resistence coefficient (K):
K : 0.0
7. velocity (v1):
v1 : 1.9583896 m/s
8. velocity (v2):
v2 : 1.9733074 m/s
9. cross section area (A):
A : 71.25574 mm2
10. friction coefficient (f):
f : 0.019850368
11. Reynolds number (Re1):
Re1 : 508012.66
12. boundary layer (δ):
δ : 0.0060742446 mm
13. pressure on the pipe start (p1):
p1 : 3600 psi
14. pressure on the pipe end (p2):
p2 : 3583.8323 psi
15. pressure drop (p1-p2):
p1-p2 : 16.167753 psi
16. temperature (T):
T : 288 K
17. kinematic viscosity (ν):
ν : 14.405283 mm2/s
18. dynamic viscosity (μ):
μ : 1.03E-005 Pas
19. gas constant (R):
R : 518.8 J/kgK
20. critical pressure (pcrit.):
pcrit. : 666.57 psi
21. critical temperature (Tcrit.):
Tcrit. : 190.45 K
I don't know which calculator you have used, but I get 16 psi pressure drop and pressure at the end of pipe much higher than 25 psi, that you stated.
Here is the calculation report that I have with isothermal gas flow rate calculator at:
http://www.pipeflowcalculations.com/gasflow/
Isothermal gas flow rate amd pressure drop calculator
1. volumetric flow rate at normal conditions (qn):
qn : 116 ft3/min
2. mass flow rate (w):
w : 140.91876 kg/h
3. length (L):
L : 325 ft
4. diameter (D):
D : 0.375 in
5. pipe roughness (kr):
kr : 0.01 mm
6. local resistence coefficient (K):
K : 0.0
7. velocity (v1):
v1 : 1.9583896 m/s
8. velocity (v2):
v2 : 1.9733074 m/s
9. cross section area (A):
A : 71.25574 mm2
10. friction coefficient (f):
f : 0.019850368
11. Reynolds number (Re1):
Re1 : 508012.66
12. boundary layer (δ):
δ : 0.0060742446 mm
13. pressure on the pipe start (p1):
p1 : 3600 psi
14. pressure on the pipe end (p2):
p2 : 3583.8323 psi
15. pressure drop (p1-p2):
p1-p2 : 16.167753 psi
16. temperature (T):
T : 288 K
17. kinematic viscosity (ν):
ν : 14.405283 mm2/s
18. dynamic viscosity (μ):
μ : 1.03E-005 Pas
19. gas constant (R):
R : 518.8 J/kgK
20. critical pressure (pcrit.):
pcrit. : 666.57 psi
21. critical temperature (Tcrit.):
Tcrit. : 190.45 K
I don't know which calculator you have used, but I get 16 psi pressure drop and pressure at the end of pipe much higher than 25 psi, that you stated.
Pipe flow calculations - since 2000
Re: Size of line for CNG slow fill
Thank you for your help on that little problem