# 7.9 Laminar Flow in Valves, Fittings, and Pipe

SAE 30 oil at 100 deg F flows through a 5” schedule 40 pipe at 400 gal/min.

There is a sketch in the Crane document of the system.

Find the velocity in feet/second and the pressure drop.

    [1]:

    from fluids.units import *
    from math import pi
    from fluids.constants import g
    g = g*u.m/u.s**2

    dH = 50*u.foot
    L = (175+50+75)*u.foot
    mu = 130*u.cP
    rho = (62.364*0.87)*u.lb/u.ft**3
    NPS, Di, Do, t = nearest_pipe(Do=5*u.inch, schedule='40')

    Q = 400*u.gallon/u.min
    A = 0.25*pi*Di**2

    v = Q/A
    Re = rho*v*Di/mu
    fd = friction_factor(Re=Re, eD=0.0018*u.inch/Di)
    ft = ft_Crane(Di)

    K_gate = K_gate_valve_Crane(D1=Di, D2=Di, fd=ft, angle=0.0*u.degrees)
    K_angle = K_angle_valve_Crane(D1=Di, D2=Di, fd=ft, style=1)
    K_elbow = bend_rounded(Di=Di, bend_diameters=1, angle=90*u.degrees, Re=Re, method='Crane')

    K_tot = K_elbow + K_gate + K_angle
    K_tot += K_from_f(fd=fd, L=L, D=Di)

    dP = dP_from_K(K=K_tot, rho=rho, V=v) + rho*g*dH
    dP.to(u.psi), v.to(u.foot/u.s)

    [1]:

    (26.063989664869815 <Unit('pound_force_per_square_inch')>,
     6.414177533606955 <Unit('foot / second')>)

## Intermediate calculations

    [2]:

    K_gate/ft, K_angle/ft, K_elbow/ft

    [2]:

    (8.0 <Unit('dimensionless')>,
     150.0 <Unit('dimensionless')>,
     20.00000000000006 <Unit('dimensionless')>)

    [3]:

    K_tot

    [3]:

29.991124449003742 dimensionless

    [4]:

    v.to(u.ft/u.s)

    [4]:

6.414177533606955 foot/second

    [5]:

    fd, ft

    [5]:

    (0.0381948926809522 <Unit('dimensionless')>,
     0.01543941031464228 <Unit('dimensionless')>)

## Proof system is laminar

    [6]:

    Re.to(u.dimensionless)

    [6]:

1675.616699190696 dimensionless