Are you asking if you can do a flow test from the pumper connection? If
so, then sure you can. You just need to modify the coefficient based on
your pitot.
How are you inflating the gpm? If you measure 1200 gpm from the 2½" and
you measure 2000 gpm from the 4.5", how is that inflating flow? You
should typically have a lower residual pressure when flowing the pumper
connection than the 2½" connection.
If you are looking to 291 for direction, are you getting the required
25% drop in static and residual from your 2½" flow? If not, what do you
do? You are required to open up additional hydrants to get the flow.
So, to get additional flow, you can also flow from the pumper connection.
Maybe I am misunderstanding your question.
Travis Mack, SET
MFP Design, LLC
2508 E Lodgepole Drive
Gilbert, AZ 85298
480-505-9271
fax: 866-430-6107
email:[email protected]
On 5/13/2014 1:47 PM, Sean Lockyer wrote:
Here is an interesting question: In the event that you do not have an adequate amount of water
flow (in terms of GPM) is it acceptable to flow the 4-1/2" pumper connection in lieu of
the standard 2-1/2" connection on the side ? I know that in NFPA 291 it is recommended to
only blow off the 2-1/2" outlet but when you blow off the pumper connection there is a
formula used to reduce it. However, even after the formula reduction you still have a far
higher amount of water (once again, in terms of GPM). My question is this, can you use that
GPM in your hydraulic calculations ? I would have to think that most AHJ's would be hesitant
to allow this to be used since you are artificially inflating the water supply.
What does everyone else think ?
Sean Lockyer
Project Designer 4617 Parkbreeze
Court
Cell 386-279-1197 Orlando,
Florida 32808
[email protected] Phone: 407-816-9101
www.AITLifeSafety.com Fax:
407-816-9104
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