How to calculate the flow requirement of an ESFR system? 2

[scythe13]

I have chosen ESFR-25 sprinklers for a warehouse, and I considered the number of activated sprinklers to be 12, and the min gpm of each sprinkler to be 158. So, the required flow is 12x158=1896 gpm

So, can I choose a 2000 gpm pump? And what's more, is it a good idea to propose two pumps, one duty and the other for stand by?

Many thanks

 

[LCREP]

K25 protect class I-V commodity and Grp A plastic, non-expanded in boxes. If you have other then this look out the protection MAY not be adequate.
NFPA 20 will let you go to 140% of the pump rating so 1500gpm will work. Some insurance companies will limit the pump to a max of 100-120% so check with the carrier. Also make sure the max pressure is 175 psi at pump churn.PRV are not permitted by NFPA 20 to reduce the pressure below 175psi. The 2000 gpm pump may give you a higher pressure at the top of the curve.Only 1 pump is required in the USA.Some insurance companies MAY require a back up tank and pump when you get over say $250-300 million so check.

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Fire Sprinklers Save Firefighters’ Lives Too!

 

[SprinklerDesigner2]

Be careful with specific state requirements as well. I doubt you are in Georgia but....

In Georgia

http://www.gainsurance.org/External...e Safety Standards - effective 03-09-2010.pdf

RULES AND REGULATIONS OF THE SAFETY FIRE COMMISSIONER
CHAPTER 120-3-3 RULES AND REGULATIONS FOR THE STATE MINIMUM FIRE SAFETY STANDARDS

On page 28:

3. In Table 12.4.2(d), change the number of sprinklers in the 25.2 Nominal K-factor rows from “12 (see Note 3)” to “15 (see Note 6)” and add the following Note 6:
“6. The design area shall consist of the hydraulically most demanding area of 15 sprinklers, consisting of five sprinklers on each of three branch lines. The design area shall include a minimum operating area of 1,200 square feet (111.5 sq m).”

I am curious as to what caused the Georgia fire marshal to make the change concerning K25 sprinklers. Does anyone else in other states have a similar rule change?

 

[b1ueshift]

'So, the required flow is 12x158=1896 gpm'

The required flow is different to this. The minimum gpm is 158 but some sprinklers will be discharging more than others depending on the hydraulics.

If you are doing a preliminary design for estimating purposes, you should add a 'wastage' allowance to the flow rate (about 10%).

As for two pumps - this is not mandatory under NFPA standards, but a lot of authorities require it. Which country are you in?

 

[scythe13]

Thanks for your answers, I am in Turkey

One more question, if I add hydrant valves and hose reel cabinets how it affects the pump sizing?

 

[MGXFP]

You can move part of the hose streams inside the building; that could affect your pump size. Say 2x 50 GPM or 1x 100 GPM. I doubt it would change much however. Certainly worth investigating.