John, That sort of is my point. I have heard of BFP issues with ITC flows
as
well. My question is what new problems are we going to learn about at full
flow
that would not show up at ITC or 2" drain flows?
Todd G Williams, PE
Fire Protection Design/Consulting
Stonington, CT
www.fpdc.com
860-535-2080 (ofc)
860-608-4559 (cell)
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On Tue, Jun 23, 2015 at 5:59 AM, [email protected]
<[email protected]> wrote:
Todd, I can add cite two instances where the first check of a BFP was too
tight
at single head flow (low flow) causing the waterflow switch to cycle
therein
never reaching the retard and never tripping the alarm panel. This was
found by
conducting a proper waterflow test thru the ITC with the smallest K head in
it.
The BFP manufacturer was contacted and as happens often enough, the by the
way
answer comes out about using a special first check for low pressure water
systems. Once swapped out worked like a charm. The moral to this story,
never
ever test a waterflow switch by simply removing the cover and moving the
vane
arm by hand.
We do forward flow BFPs per 25 and have yet to see one hang. But I'm sure
that
day is coming.
John Drucker - Mobile Email
Assistant Construction Official
Fire Protection Subcode Official
[email protected]<mailto:[email protected]>
Cell/Text 732-904-6823
Todd - Work <[email protected]> wrote:
I wouldn't mind hearing this as well. I would think that between
inspector's
test flows, 2" drain flows and annual backflow preventer tests (required by
states), that the health of the BFP would be sufficiently determined. Of
course
in Light/Ordinary Hazard situations, the 2" drain could discharge system
demand,
so the requirement would be met. Perhaps a full flow as part of an
acceptance I
could understand. Have there been any instances where there has been a
backflow
preventer failure at full flow and not at a lower flow?
Todd G Williams, PE
Fire Protection Design/Consulting
Stonington, CT
www.fpdc.com<http://www.fpdc.com>
860-535-2080 (ofc)
860-608-4559 (cell)
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On Tue, Jun 23, 2015 at 1:55 AM, [email protected]
<[email protected]> wrote:
Something I have failed to understand, and would appreciate if someone can
enlighten me.
The forward flow test is required at the full system demand, presumably to
check
the operation of the BFP. If the test shows that the BFP will open at
system
demand, what guarantee is there that it will open at a lower flow. I would
think
higher the flow, greater the force and easier to open the check valves. Or
am I
missing something?
Tony
----- Original Message -----
From: "Brad Casterline" <[email protected]>
To: [email protected]
Sent: Monday, June 22, 2015 10:42:17 AM
Subject: RE: BFP_Compare_Roland
Hello Forum,
Two weeks ago I said:
"I fixed it and compared the results for a wide range of flows to the
results in Roland's article and I will never bad-mouth Hazen, Williams, or
Roland again :)."
Here is a summary of the more exhaustive comparisons for the 2" and 2 1/2"
Main Drain scenarios:
https://www.dropbox.com/s/1tqp42gqdpxum04/BFP_Compare_Roland.pdf?dl=0
and here is the link to the issue of Roland's article:
http://digital.turn-page.com/i/127056-may-2013
I added (5) quantities to each calc:
1) velocity
2) HW pf/ft
3) DW pf/ft
4) HW va eq len
5) DW va eq len
Looking at 4) and 5) you might see why I said, "My concept of K-Value and
Pf
and equivalent length being proportional to v^2 was exactly backwards."
I hope a Forumite or two finds this kind of thing as interesting as I do!!!
Thanks,
Brad Casterline
AFSA Designer Member and SET
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