I've always read it to apply to any pump arrangement even if just a
single pump would do. The text says that the demand shall be meet
with the largest pump out of service. If you have just one pump -
THAT is the largest pump so it must be taken out of service. Thus two
pumps are required.
Roland
On Oct 5, 2011, at 2:30 PM, <[email protected]>
<[email protected]> wrote:
Are you talking about redundant primary fire pumps or redundant foam
concentrate pumps?
Redundant foam concentrate pumps are in 6.2.7.
Redundant primary fire pumps aren't specifically listed as being
required per 409. However since many of these installations can
have large fire flow demands there are often multiple pumps
installed. When that occurs the pumps may or may not all be of
equal size. 409-6.2.10.8.2 states that "The total pumping capacity
shall be such that maximum demand can be met with the largest fire
pump out of service." This assumes a multi-pump installation.
I had a project last year where there was a 2000 gpm electric and a
4000 gpm diesel. This setup did not meet 6.2.10.8.2 since the
electric could only do half of the diesel and could not meet demand
of the largest flow on the site if the diesel was out of service.
Now some EOR/AHJ types might read this and deem that it infers
redundant pumps as being required based on this wording.
Craig L. Prahl, CET
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