## Hoses and Branch Pressures

- Details
- Published: Sunday, 28 December 2014 11:24
- Written by Lance Hartley

### Loss of pressure due to friction loss

- Friction loss varies directly with the length of the hose or pipe. (e.g.
**Double the length of the hose and you get double the friction loss**.) - For the same velocity, friction loss decreases directly with the increase in diameter. (e.g.
**Double the diameter and you will halve the friction loss for the same velocity**) - Friction loss increases in proportion to the square of the water velocity. (e.g. Doubling the water’s velocity increases the friction loss by four.)
- Friction loss increases with the roughness of the hose’s interior. (e.g. All other things being equal, water moving through a rough unlined hose has a higher friction loss than in a smooth lined hose).
- Friction loss, for practical purposes, is independent of pressure. In the RFS, the "rule of thumb" rate of friction loss is 100 kPa per 30 metre hose length.

### Typical Branch Pressures

Branch Type |
Optimum Pressure |
Other Notes |

Dial - A - Jet | 500 kPa | Each 30 m length of hose costs 100 kPa in pressure |

AWG | 500 kPa | Every metre elevation costs 10 kPa of pressure |

Elkhart | 700 kPa | |

Akron | 700 kPa |

### Questions

- Using RFS "rules of thumb" for friction loss and height loss / gain, what pump pressure would be needed to supply a nozzle at 500 kPa at the end of a single line of hose consisting of 4 x 30 metre lengths, with the nozzle 15 metres above the level of the pump? (1050 kPa at the pump)