Water Demand & Booster Pump Lab
Count the fixtures, convert them to water supply fixture units and a probable peak flow with the Hunter curve, then size the booster set: pressure zones that keep every outlet between the minimum and maximum pressure, pump duty, power and the riser size. Play a day of demand to see how the pumps stage.
How to use: enter fixtures per typical floor and the number of floors. Fixture unit values are typical IPC figures you can edit. Tap i for explanations.
1. Building and fixtures
Fixtures per typical floor, all floors alike.
2. Pressure zones
Static pressure on every floor with zones and pressure reducing valves marked.
3. Checks
4. Demand and zones
5. How it works
Fixture units and the Hunter curve
Every fixture gets a water supply fixture unit (WSFU) value reflecting how much and how often it draws. The total does not add up linearly: the chance of all taps running at once falls as the number grows. The Hunter curve turns total fixture units into a probable peak flow, which is what pipes and pumps are sized for.
Pressure zones
Every outlet needs enough pressure to work (shower mixers about 1 to 1.5 bar, flush valves more) and no more than the maximum (5 bar in AS/NZS 3500.1 and common UAE practice) to avoid noise, splashing and wear. Height adds 0.0981 bar per metre, so a tall building is split into zones, each with its own pump set or pressure reducing station.
Booster set
Variable speed booster sets with several pumps cover the peak with one standby and run one small pump most of the day. Pump power is flow × head / efficiency.
Learning and checking tool. Use the fixture values and method your authority adopts, for example the Dubai Building Code, IPC, BS EN 806-3 or AS/NZS 3500.1.