SAE oil is discharged at 15 degrees Celsius from a tank with 7 m of head to atmosphere through:

- 60 meters of 80 mm schedule 40 pipe
- Six 80 mm standard 90 degree threaded elbows
- One 80 mm flanged ball valve, with a 60 mm diameter seat, 16 degree conical inlet and 30 degree conival outlet.
- The entrance is sharp-edged and flush with the tank

This is the same problem as 7.6, except the properties of the fluid are sufficiently viscous to put it into the laminar regime although not by much.

```
In [1]:
```from fluids.units import *
from math import pi
rho = 875.*u.kg/u.m**3
mu = 78*u.cP
H = 7*u.m
L = 60*u.m
NPS, D_pipe, Do_pipe, t = nearest_pipe(Do=80*u.mm)
fd = 0.017
Re = 1E5
for i in range(20):
K = K_from_f(fd=fd, L=L, D=D_pipe)
K += entrance_sharp()
K += exit_normal()
K += 6*bend_rounded(D_pipe, angle=90*u.degrees, fd=fd, bend_diameters=0.65)
ball_valve_angle = 0.5*(15+30)*u.degrees # use the average angle
K += K_ball_valve_Crane(D1=D_pipe, D2=60*u.mm, angle=ball_valve_angle, fd=fd)
v = (2*u.gravity*H/K)**0.5
Q = v*pi/4*D_pipe**2
print('Flow rate = %s, Reynolds number = %s' %(Q.to(u.L/u.min), Re))
Re = Reynolds(D=D_pipe, rho=rho, mu=mu, V=v)
fd = friction_factor(Re=Re, eD=0.0018*u.inch/D_pipe)

```
```