The WSFU (Water Supply Fixture Units)
- 1 WSFU = 1 GPM = 3.79 liter/min
Note that this conversion is only true for one or a few fixtures. Since all fixtures in a system are never used at the same time, the total units achieved by adding the numbers for all fixtures must be compensated for their intermittent use.
For supply pipe lines this is taken care of in the sizing tables.
For manifolds or special equipments sizing, a formula or a table can be used.