Water Supply & DistributionQuestion 55 of 120
Using the standard fixture unit to gpm conversion curve, what happens to the estimated demand when the total water supply fixture unit load on a system is doubled?
a.The demand in gpm exactly doubles
b.The demand in gpm increases by less than double
c.The demand in gpm more than doubles
d.The demand in gpm stays the same
Explanation
The conversion curve is probability based: as more fixtures are added, the chance that all of them run at once drops, so gpm rises more slowly than fixture units. This diversity is why a 200 WSFU building does not need twice the flow of a 100 WSFU building. Assuming a straight-line doubling oversizes the service, and the more-than-double and no-change answers contradict how the curve behaves.
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