In the practical analysis of piping systems the quantity of most importance is the **pressure loss due to viscous effects** along the length of the system, as well as **additional pressure losses**arising from other **technological equipments** like, valves, elbows, piping entrances, fittings and tees.

At first, an **extended Bernoulli’s equation** must be introduced. This equation permits account of viscosity to be included in an empirical way and quantify this with a physical parameter known as **the head loss**.

### Summary:

**Head loss**or**pressure loss**are the reduction in the**total head**(sum of potential head, velocity head, and pressure head) of a fluid caused by the**friction**present in the fluid’s motion.**Head loss and pressure loss**represent the same phenomenon –**frictional losses**in pipe and losses in hydraulic components, but they are expressed in**different units**.- Head loss of hydraulic system is divided into
**two main categories**:**Major Head Loss**– due to friction in straight pipes**Minor Head Loss**– due to components as valves, bends…

**Darcy’s equation**can be used to calculate**major losses**.- A
**special form of Darcy’s equation**can be used to calculate**minor losses**. - The
**friction factor**for fluid flow can be determined using a**Moody chart**.

- A
**special form of Darcy’s equation**can be used to calculate**minor losses**. - The minor losses are roughly proportional to the
**square of the flow rate**and therefore they can be easy integrated into the Darcy-Weisbach equation through**resistance coefficient K**. - As a local pressure loss
**fluid acceleration in a heated channel**can be also considered.There are following methods:

See also: