NFPA 219 flow testing hydrants, 25% drop

[davidfire]

Hi,
Im trying to comply with the 25% drop in residual\static specified in NFPA 219 when carrying out hydrant flow testing. example below
Remote static 158 psi
hydrant 1 open with residual 154psi and flow 2627 lpm
hydrant 2 open with residual 140psi and total flow (x2 hyds)4735 lpm
hydrant 3 open with residual 116psi and total flow (x3 hyds)6545 lpm
total flow 6545 x (158-20)0.54 / (158-116)0.54 = 6545 x 138 0.54/42 0.54 = 9320 lpm Is this correct?

also
if I had a fire pump with a gauge that showed 170psi and the pump gauge drops whilst opening the hydrants, should I include this in my theoretical calc? if so how?
Thanks for any help

 

[davidfire]

me again!! sorry my theoretical calc should've said 12442 lpm.

 

[davidfire]

can anyone help me?

 

[cdafd]

Sorry have not done a flow test with a fire pump
On the line and do not know if it is figured in
I think you may have a good representation of the water supply

 

[cdafd]

4.3.6 To obtain satisfactory test results of theoretical calculation of expected flows or rated capacities, sufficient discharge should be achieved to cause a drop in pressure at the residual hydrant of at least 25 percent, or to flow the total demand necessary for fire-fighting purposes.

""" to flow the total demand necessary for fire-fighting purposes"""""

what is your demand you need??

 

[davidfire]

The area is a storage tank farm so the demand for fighting purposes will easily be exceeded and additional water supplies required!

 

[chicopee]

The way that I am viewing your numbers is that you have a total of 6545 lpm at a residual pressure of 116 psig taken at the remote static point which I assume is a fourth hydrant; Hydrant flows at 2108 lpm and hydrant 3 flows at 1810 lpm. So plot the remote static value of 158psig and the 6545 lpm at 116 psig on semi-log graph of N=1.85 power to see what lpm at 20 psig the graph shows. I have included an attachment of the graph in question with your values. At 20 psig, 3270 gpm translates to 12376.9 lpm and 3540 gpm translates to 13398.9 lpm.

 

[chicopee]

That s/b "...Hydrant 2 flows at 2108 lpm and hydrant 3 ......"

 

[sfallows]

Is it just me or I don't see NFPA 219
[URL unfurl="true"]http://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asp[/url]

 

[skdesigner]

NFPA 291 Recommended Practise for Fire Flow Testing and Marking of Hydrants

Slip of the typing finger, it would appear.