A small fire protection system is to be modeled. The sprinkler
system is supplied from city water. The sprinkler headers are
maintained pressurized using an air-loaded tank (minimum pressure
of 50 PSIA). This tank provides the initial pressure source
and water volume until the two parallel pumps are up to speed.
sprinkler system protects three floors of the building. Each
floor consists of a single header (including both a 4 inch section
and a 2 inch section) which supplies 8 sprinkler nozzles (at
approximately 15 foot intervals). The system is to be designed
so that the sprinklers on all three floors can be supplied at
the same time. The sprinkler nozzles are designed to provide
a minimum of 15 GPM with an inlet pressure of 25 PSIA. Further,
inlet pressure to the nozzles must be maintained less than 40
PSIA to maintain a safe flow rate out of the nozzles.
The question to be answered is whether the initial tank pressure
(50 PSIA) is sufficient to meet the design constraints at the
The network layout is built first. Since all three floors are
similar, a single floor layout is first constructed and then
copied to create the other two floors. The remainder of the
hardware is then added.
fluid is then specified. For flow information, the tank pressure
(50 PSIA) and the nozzle discharge pressures (14.7 PSIA) are
specified. DesigNet will then automatically calculate flows
to each nozzle. By displaying the flow rates, it can be quickly
determined whether the tank pressure is sufficient to meet the
design constraints listed above.
can include graphical reports showing the network layout and
flow values (pressures and flow rates, amongst others).