# Pump bypass line on tank/pump system



## rth (Jun 27, 2019)

Applicable codes per build:
IBC - 2015     IFC - 2012

800,000 square foot tire manufacturing plant

350,000 gallon ground tank feeding twin 4,000gmp pumps supplying the system and the hydrant loop separately with a pressure reducer (80psi) on the hydrant side. Incoming water feeding the tank is 10" main that has typically has a static pressure above 80psi and often 100psi.

The incoming feed line to the tank does not bypass the tank/pump or feed the system in any way at all. It just goes to the tank only. I've pointed out the risk of this to FM global and all involved with the tank/valve/pumps being a single point of failure for the entire system (hydrant loop included) with no other way of getting water into  the system. FM global wrote me back saying they are restricted by fire codes and do not see a problem with it.

Found 2016 NFPA 20 4.15.4.1 "Where the suction supply is of sufficient pressure to be of material value without the pump, the pump shall be installed with a bypass."

I'm getting push back that this does not apply to a pump/tank system, that this is just for a pump system that is directly fed by muni water.  

What do you guys think?


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## cda (Jun 27, 2019)

Ok will give my non engineer, non sprinkler designer, just been at a lot of holiday inn answer,,,,

My understanding over the years

1. If tank is involved, it has to hold the amount of water,,, for the time NFPA  requires.

2. For get what the refill time is on a tank.

3. Yes a by pass is required on an actual fire pump.

4. A by pass would not do much good if the city main pressure cannot supply the demand.


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## cda (Jun 27, 2019)

I normally have a couple of go to sprinkler experts, I bounce questions off and can trust their answers.


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## cda (Jun 27, 2019)

https://www.qrfs.com/blog/123-a-gui...rinkler-systems-for-facility-managers-part-6/


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## cda (Jun 27, 2019)

Not sure if this is what 22 requires::


The water storage must be self-replenishing. It must reach required volume during normal consumption within 48 hours, and within 24 hours curtailing normal consumption.



It may require eight hour refill


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## rth (Jun 27, 2019)

NFPA 20 does not say that it has to meet demand, it says that if it is of material value.

I'm just looking at the big picture here and the risk involved and trying to find an answer in the code and I'm feeling a bit let down by the code here.

The way this system is designed if the tank fails or is empty for any reason not only is the entire suppression system out but also every hydrant on the property as well. In a suppression system this size it seems unreasonable to not have a back up for what little it would cost to run that 10" supply main over and tie into the discharge side of the system and the hydrant loop.


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## cda (Jun 27, 2019)

I agree with your concern, but I do not believe it is required by NFPA.

You could ask for it, if this is a new build.

Once again if the city underground cannot meet the demand, not much good, more feel good. 


“”Insurance Engineer” should see this and give more detail.

Or write him with the question.


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## cda (Jun 27, 2019)

So a question, before the city water main enters this property 

What does the flow test show as far as static, residual, and flow gpm???


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## e hilton (Jun 27, 2019)

rth said:


> What do you guys think?



I have no idea what code requires, buf if a risk has been identified and a reasonable solution is available ... seems like its stupid not to implement it.   Sounds like a pipe and valve can be added to provide a decent level of operation.  Maybe not the ideal level, but if the main pump fails something is better than nothing.


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## cda (Jun 27, 2019)

“”I'm getting push back that this does not apply to a pump/tank system, that this is just for a pump system that is directly fed by muni water. “””

If not in NFPA 22, than it cannot be required.

It can be asked for.


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## cda (Jun 27, 2019)

Ok after reading the question a few times,

Besides I do not think it is required,

I think indirectly the bypass is there.

If the tank has any water in it, and the fire hydrants are fed off the fire pump, the water should flow through the “fire pump by passes” to the entire fire protection system.

Maybe if not there yet, a fdc to feed the hydrants and fire sprinkler systems.


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## cda (Jun 27, 2019)

Keep on thinking on this 

If there were a bypass, some how it seems like a shut off manual or automatic would be required, to assure the tank is filled and kept filled.


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## cda (Jun 27, 2019)

Looks like NFPA 22 also references you to NFPA 24.


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## cda (Jun 27, 2019)

Since you made me look I do not see anything in 22 or 24, that would indicate a bypass is required, except as per 20 for the fire pump.


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## rth (Jun 27, 2019)

I just thought since it was required in NFPA 20 and IFC referenced 20 for pump installation that it was a requirement.


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## cda (Jun 27, 2019)

rth said:


> I just thought since it was required in NFPA 20 and IFC referenced 20 for pump installation that it was a requirement.




Only if NFPA 20 applied to underground pipe and mains.


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