Lets start over again since I think the birds have already grabbed the
bread crumbs.
You have a supply tank for both sprinklers and hydrants. After the
pump, the hydrant and sprinkler paths diverge. Do you need to add the
hose demand to the sprinkler calc - right? What difference would
this be from a street main supplying both? The two tank comparison is
the same as two separate municipal supplies feeding each. I must be
missing something since I see no potential confusion so take another
stab at 'splainin'.
Roland
On Jun 29, 2011, at 12:59 PM, Ron Greenman wrote:
Right and that is accounted for. I can flow both hydrant and sprinks
simultaneously for the total duration of each. I may or may not need a
pumper at the hydrant. This is actually more of a pressure question
and is
just theoretical. If the hose stream portion of the sprinkler demand
crosses
the the supply curve from the pump so I don't have the required flow
at with
the hose stream but there is more on-site water than I need to flow
both
(and that is not subject to demand fluctuations from other users) I
can
adjust my pump curve. The question though is why should I need to
add that
demand on the sprinkler calc where the supply to the sprinks and the
supply
to the hydrant diverge? This is akin to doing a rack calc and an
overhead
calc and then adding an arbitrary extra amount of gpm at the common
point of
divergence from the main after you've balanced the two. There's no
problem
to overcome since in the actual case the hose demand can be added
without
causing the problem but it did bring up the question of why does it
need
inclusion in the first place under these conditions. The obvious
parent
answer is because I (the code) say. All the exceptions are for
process water
and when there are only sprinklers on the tank. If I had a small
elevated
tank for the sprinks only and another for the hydrant only I
wouldn't have
to include hose stream but when I combine the both in the same tank
I do.
Doesn't make sense to me.
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