A deeper discussion on NFPA 20 compared to common practices outside USA 2

[annoynimous]

Dear all,

After studying NFPA 20 for some time, I feel like there are some major practices in NFPA that is different to anything we've been learning from our local AHJ in Asia.

The biggest one that's been bugging me, and I would like to discuss today to have a better clarity, is the topic on having a Duty and Standby Fire Pump.

Correct me if I am wrong, but this practice is non-existent in NFPA and perhaps non-mandatory in the States?

I've watched some Youtube videos on Fire Pump testing in America and never once have I seen the fire inspector describing anything about testing two identical fire pumps, one being a standby...

Would appreciate some feedback regarding this as I have never had the privilege to travel to the States to learn more.

Thank you

 

[TravisMack]

It is rare to have a standby pump on non-industrial, highly protected risk, or military projects.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, a Ferguson Enterprise

http://www.mfpdesign.com

 

[UFT12]

NFPA 20 doesn't even mandate one pump, not to mention two, provided the water supply in terms of flow, pressure and duration are reliable and adequate. To put it differently, just as NFPA 13 is a standard on how to design and install sprinklers but not to mandate them, NFPA 20 does pretty much the same. It provides all information necessary for pump installations but does not necessarily require them. What you may want to have a look on is about other various statutory documents pertinent to your jurisdiction such as building/fire codes or specific to the installation and hazard documents typically issued by insurance carriers. These often make their own evaluation of the hazards and risks involved for the given investment and in installations of high value may mandate even more that two pumps.

 

[annoynimous]

thanks for the info guys! @TravisMack and @UFT12

 

[stookeyfpe]

One exception is fire pumps in Very Tall Buildings. If the high rise height is beyond the capabilities to deliver 250 GPM to the highest occupied floor, NFPA 20 does specify redundant fire pumps.

 

[annoynimous]

hi stookeyfpe, let me briefly explain what I meant in my opening thread...

Our local AHJ has been practising British Standards for ages, most likely passed down from post-colonisation days.

Since the day I have been introduced to fire pumps, we have always been taught to size out two identical sprinkler/wet riser pumpsets for any building.

They are usually pre-determined as one duty and one standby pump. The duty pump will be sized accordingly to serve the entire building.
The role of the standby pump (usually a diesel set), is to act as a back up pump just in case the duty pump (usually an electric motor set), fails to run. So yes, in terms of purchasing and maintenance costs, and pump room spacing, owners of commercial buildings will have to suck it up and comply with this requirement. The standby pump will only come in when the pressure drops below the duty pump's cut in pressure settings.

However, because of these practices, we never had to deal with control panel failure and emergency starts as seen in NFPA 20, because our local AHJ treats the standby engine pump as the emergency back up.
Across-the-line starting was never ideal for all countries anyway, especially once the motor size increases to a size where the 600% of FLA for Across-the-Line is too taxing.
In the case of Asian countries, where power stations and power lines are not generously sized to perform such feats, and local electrical contractors main concern is cost saving & more cost saving, soft starting has always been the most preferred choice.