# Blog Archives

## Closed Conduit Hydraulics - Friction and Minor Losses

Friction and minor losses are glossed over in the darcy-weisbach article but I want to throw in some extra notes here. Friction occurs over every bit of length of a close-conduit system and is usually a surprisingly high amount of energy loss. Friction depends on the material of the pipe and the velocity of flow. The formula for frictional head loss IS the Darcy-Weisbach equation.

## Closed Conduit Hydraulics - Bernoulli Equation

The Bernoulli Equation is used to analyze flow in closed pipe systems and is one of the most used equations in hydraulics (that I can remember!).

The base form of the equation relates energy between two or more points in a system. I think it is easier to remember and use in terms of head loss(ft or m).

## Closed Conduit Hydraulics - Hazen Williams Equation

Hazen-Williams can be used to determine the flow characteristics in closed conduits (pipe systems).

### For Velocity

S = slope, in decimal form. This is equivalent to $h_f/L$

R = hydraulic radius, $\text{(Area of flow)}/\text{(wetted perimeter)}$

C = Roughness Coefficient, get this from a tableÂ (available in both theÂ AIOÂ andÂ CERM) Click here to continue reading

## Closed Conduit Hydraulics - Darcy-Weisbach Equation

The Darcy-Weisbach equation is used to determine flow characteristics in closed conduit systems (pipes). It is probably more common than the Hazen-Williams equation due to it being able to solve for systems in both laminar ANDÂ turbulentÂ flow.

• headloss $h_f$ (ft)
• friction factor $f$, length $L$
• length $L$ (ft)
• diameter $D$ (ft)
• velocity $V$ $\frac{ft}{s}$
• gravity g $32.2 \frac{ft}{s^2}$

#### Friction Factor

The friction factor $f$ is either given or must be calculated using a Moody-Stanton diagram (available in both the AIO and CERM). Getting the friction factor from a Moody-Stanton chart requires the Reynolds Number $Re$, and relative roughness $\dfrac{\epsilon}{D}$. Click here to continue reading