Has anyone encountered the situation that the use of two diesel pumps in one pumping room was questioned. One water tank.
I'll appreciate any early answers.
2 diesel driven fire pumps are recommended where property value exceeds 100 million USD. Personally, I think one diesel pump is enough. My experience is that one well maintained pump (per NFPA 25) is more reliable than two or more not maintained pumps.
Of course, it is a bit questionable but if there are no alternative solutions that's fine. NFPA is only worried about the fire fighting system's operation in an emergency condition. the source of the power for the fire fighting system should be
Thanks for an early answear. I realize 1 tank could be questioned which is obvious, not 2 diesel pumps.
BTW I consider this scheme as safe. Just curious what is your experience.
San Francisco High-rise building now require a 10,000 gallon tank and a diesel and electric fire pump in each building. There is also one high-rise that had two fire pumps as a safety factor becsue of the value. Air Force hangers frequently have multiple pumps for reliability and the volume needed.
Greg give me 1 advantage of using electric pump instead of diesel pump. When power supply is not that reliable as you have in San Francisco.
There is no doubt that the reliability of a diesel does appear to be greater than that of an electric fire pump due to power outages but a sound risk assessment will consider the overall reliability of the scheme. Since they each have different failure vulnerabilities there is risk on either side (i.e., type of pump). The article linked to above provides very good insight on the risks of both and especially of the diesel. One risk omitted in the article was bad fuel which is a very real possibility. It can either be from the quality received or the degradation of the diesel over time and I have read of it shutting down eight backup generators simultaneously. Without going into details of all of the failure modes of both types of pumps, an overall risk assessment will tell you that, statistically, you cover more risk scenarios when you have one of each type of pump and therefore the overall reliability would higher. To answer your question then, the advantage of providing an electric pump as the second one is that it will raise the overall reliability of the scheme.
appreciate your comment, but you will have the same disadvantages in power generator that is obligatory in this scheme of 1 diesel + electric. Also you can face difficulties during start as you have delta configuration on your electric motor instead of star.
Not sure why it would be questioned. We have two fire pumps at almost all of our locations because of the value of the building and its contents. I design and require 2 pumps for all of our newer buildings but its usually 1 diesel and 1 electric ( if the electric is backed up by generator) otherwise we have 2 diesel pumps. We have never been questioned by the AHJ or our insurance company (FM Global).
I'm not sure what your actual question is, whether it's that you have two instead of one fire pump, or it's two fire pumps in the same room. One issue I haven't seen brought up yet is whether the two diesel fire pumps have a fire barrier between them since they're in the same room and whether their power supplies are separated. If they're both 100% redundant, if you were to have a fire in the pump room, you could potentially lose both fire pumps without them being adequately separated.
For example, at our facility (a nuclear power plant), we've received questions from the regulator on the fact that we have 3 100% capacity electric fire pumps in one room without adequate separation. The three pumps were not separated by fire barriers and the power cables were routed through the same cable tunnel. To mitigate this, we have an additional engine driven 100% capacity fire pump in a separate building with the cables routed separately, and two other 50% engine driven pumps that can be manually cross-tied from a separate fire main.
My question was about 2 diesel pumps (1 is 100% redundant). During my 15 years "sprinkler" career, for a first time it was questioned for the reason of only 1 type of power source (diesel) is used. For the person that questioned this scheme, it "seemed to be" not reliable, which I will never agree. Pumping room is protected with K115 sprinklers, pumping room is fire separated for a 1 hour. Pumps will be maintained acc. to NFPA 25.
The reason I used second diesel pump (redundant) is a value of facility which significantly exceeds 100 000 000 $.
It was easier to use 2nd diesel pump which is more reliable than electric pump if we compare it without second source of electric power (generator or second independend connection). Cost of generator + cost of fire rated electric cables (it's a must in my country) make electric pump much more expensive.
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