Remove a Redundant Fire Pump from Service?

3/13/2020

My employer owns several properties in with 2 fire pumps that are discharging to the same loop. The pumps were there when we bought the buildings. In most cases there is one electric and one diesel, but in other cases there are two diesel fire pumps.

The power purveyor is not considered unreliable by any criteria.

Is there anything you can think of that would prohibit me from decommissioning a redundant pump for the purpose of saving on maintenance costs?

Each pump is 2000 gpm and the greatest demand on the loop is less than 3,000 gpm. The pumps are provided in parallel.

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10 Comments

Scott

3/13/2020 10:04:00 am

There might be an insurance company requirement above the normal fire/building code requirements. I used to work for a large insurance company and once buildings got to a certain insurable value, they would require redundant pumps with separate power supplies.

Efi Sher

3/13/2020 10:10:43 am

2 diesel pumps doesn't make sense.
One electric and diesel is OK.

sean

3/13/2020 01:13:13 pm

you still get redundant pumps.

3/13/2020 10:14:13 am

The maintenance costs on your existing fire pump would be far less then you would spend if you would have to replace it. Penny wise and dollar foolish. ( Not calling anyone foolish, but that is how he saying goes.)

Joseph

3/13/2020 10:17:22 am

Consider consulting a maintenance and reliability professional to determine the availability and reliability of your system. Any reported failures or periods of unavailability could help derive the reliability of each pump. Note, consider including lead time for parts and repair personnel schedules in the periods of unavailability to calculate "operational availability". If the respective reliability calculations for each individual pump drops to 70%, having them in a redundant configuration still achieves a system reliability of 91% assuming the switch from one pump to the next is 100%. Compare the availability and reliability the owner desires against the cost of liability and cost of maintenance on the additional pump.

Jesse Cecil

3/13/2020 10:26:16 am

Undoubtedly an insurance requirement. If the properties were designated as High Protected Risk, there would most likely be 2 pumps, even two diesel pumps - though the more common arrangement is primary electric and secondary diesel.

Before working as a design manager, I was an insurance HPR engineer for 13 years. This arrangement is very common.

I'm curious as to what the occupancy is and what the extant AS protection is. J

Paul Pinigis link

3/13/2020 10:32:37 am

This is most likely an insurance company requirement.

I would not recommend removing one because the maintenance costs should not be very high, but the cost to replace the remaining one in the event of a failure would be very high. The maintenance is a small price to pay for peace of mind.

Chris

3/13/2020 11:26:46 am

The pump is 2000gpm and the greatest demand in the system is 3000gpm?
Than doesn't tell me much.
I heard so many people referring to a pump capacity as 20HP or 30HP.
The main thing when addressing a fire pump is the rated pressure and the rated flow.
Since any fire pump must deliver 65% of the rated pressure at 150% of the rated flow we don't know where is this 2000gpm is located on the graph.
When selecting a pump you want to pick a point on the graph somewhere between 90% and 130% of the rated flow and enough pressure to overcome the gap between the system demand and city's water pressure.
If your pump is rated at 100psi and 2000gpm you may be happy with the 3000gpm but you will only get 65psi at that flow so make sure both values for flow and pressure are in the right area on the graph.
Otherwise your insurance provider has a file on these systems (pumps) and your owner must have signed up for that plus the right approvals were given by local A.H.J. (Factory Mutual of IAO most likely. They are the only ones who can approve the eventual change you are talking about.

Regards

Franck

3/13/2020 11:39:13 am

All the above comments are right

In addition to possible insurance requirements (depending on Total Insured Value), in particular for HPR locations, there are also many other possibilities.

One may be a change on the design of some systems that goes beyond the characteristics of just one pump.
Normally, the pump is to be sized upon the most demanding system. And if the most demanding system is close to 3000 gpm (which is a huge demand!) then the fire pump should be rated at 3000 gpm, not 2000. So maybe the change of commodity/occupancy required that 2 pumps are needed to meet the most demanding areas.

What is your activity for having such a demand ? Storage facility ?
Maybe the previous design for the previous owner is not suitable for your activities and your actual demands are lower than the designed for 3000 gpm ? Or maybe it is even higher and you need for sure 2 fire pumps !

In any case, having 2 pumps in service is a "gift" and I wouldn't get rid of it. More flexibility for maintenance (if one pump is out of service, you don't impair all your sprinkler systems at the same time) and as already indicated by others, it can save you a lot of money when you will need to replace one pump.

Not to mention that in case of fire, the probability to have both pumps not operating is much lower than having one pump not operating.

DTC

3/14/2020 06:23:30 pm

In addition to insurance I would say consult the AHJ in our area you are required to have redundant pumps if your pump is feeding multiple buildings.

Also until last code cycle we did not consider the electric company as a reliable source.

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