Many more times than you may have heard about, Craig. For a variety of reasons,
there are more fires that exceed the full design area than you are told about.
I recently spent four days at a fire scene where part of a sprinklered, light
hazard building burned to the ground. That fire exceeded
If I had a loading dock attached to and ESFR system, I'd calc the ESFR since it
would be the most hydraulically demanding. If a fire originated on the dock
and migrated inward to the building, involving a portion of the dock and the
ESFR system, you still should be fine from a water supply
I believe the intent came from an example of a dry system loading dock attached
to an ESFR warehouse. The statement was that if we have to carry the density
over into the ESFR warehouse from the loading dock, you would be flowing an
insane amount of water. If you have a 2000 sq ft loading
I'm pretty sure that the increase of 30% goes all the way back to pipe
scheduling where the increase in area was added because of the time-delay
inherent in dry pipes from fusing to water delivery and the likelihood of
extra unnecessary heads fusing across the ceiling even if the fire itself
I've heard it explained that the intent was to drive up the size of the main
feeding the smaller area in case it was ever expanded in size, but in my
personal opinion the standard should NOT be in the business of addressing the
future. If the area gets added onto we can deal with it then by
I believe this is one of those things that has unintended consequences. As I
heard urban legend rumors, the idea was for something like a loading dock or
something. That if you added additional flow to the main, that if adjacent
sprinklers were to activate that the system would be sized to
Very good question. I've read discussions on this issue recently as well and
really wonder what was the thought process behind including a non-existent flow
value in the system design and calculations.
I would love to hear the rationale for this section.
Craig Prahl | Jacobs | Group Lead/SME
I've just been introduced to section 23.4.4.2.5 (2016). In my particular
situation, I have an EH2 refueling building (0.4 / 2,500) that is 2,268
sq.ft. in its entirety. The flow from my calc came out to 998 gpm, so I was
told by my coworker who reviewed my plans not to worry about the extra 2
gpm
