You’ve taken much of what I said out of context. I said that even when sprinklers and standpipes are combined they are separate systems HYDRAULICALLY. It is absolutely NOT required to combine the demands as you implied with your statement this morning, even with the qualifier of a partially sprinklered building. 7.10.1.3.1 implies that you cannot combine the systems if the building is partially sprinklered (it could be worded better, to be sure). In that case, you would have to determine the hydraulic demand of two completely separate systems. If a building is fully sprinklered per 13 or 13R, then you select the more demanding of the two (separate calc’s because they are hydraulically designed independently of one another) and that becomes your benchmark water supply for sizing the COMBINED system piping that serves standpipe hose connections and sprinklers.
The NFPA 14 committee added 7.10.13.1.1 in the 2013 edition BECAUSE there has been long-running debate and confusion. This change was reactive to and intended to be companion to the change in NFPA 13, 2010 edition that added A.11.1.6.6 (as it was numbered in 2010) that clarifies that it isn’t the intent to add standpipe demand as a hose stream to a sprinkler calculation. So let’s not allow history to blur the focus both committees have brought to the issue of combined systems calculation; better late than never. It IS clear in my opinion that it is not the intent of either standard to require concurrent demands in any form. Your theoretical regarding a partially sprinklered building and an automatic water supply (presumably for a standpipe system) is just that – purely theoretical. There is NOTHING in the codes or referenced standards that requires an automatic water supply be furnished for the manual (presumably Class 1) elements of a low- or mid-rise building that doesn’t require an automatic water supply. You state that it goes to reason that an automatic water supply (ostensibly to meet demand of sprinklers and/or Class II hose connections) would be calculated to meet the demand of a manual standpipe system but that would potentially entail upgrading a pump from 100 or 250 GPM to 1000 GPM, electrical system upgrades, maintenance issues, testing costs, etc., etc. It does NOT go to reason that such an application would be a good idea; manual standpipe systems are the preferred means for fire departments to control their water supplies in a fire fight. Even in a building equipped with an automatic standpipe, engineers and incident commanders are trained to not trust building systems and they will override pumps as necessary, so long as they have the capacity to pump to the top of a building with their trucks. The foregoing is my opinion only and is not intended to represent the NFPA 14 Technical Committee, nor serve as an interpretation of the standard. Steve Leyton Protection Design & Consulting San Diego, CA From: Sprinklerforum [mailto:[email protected]] On Behalf Of å... .... Sent: Thursday, February 09, 2017 12:28 PM To: [email protected] Subject: Committee Intention and Reducing Sprinklers' Pressure in a Combined Standpipe/Sprinkler System where and by whom: **Answer: robust debate and 2016 NFPA 14 -7.10.1.3.2. ** 14 is very clear: ** Answer: If very clear, Then why the robust debate for many years? If one side of the argument were clearly superior, the other side should have rested their case. Playing my own devil's advocate, it is admitted that new ideas take decades to penetrate an industry, even in this age of social media . It is as Max Plank said "science advances one funeral at a time (each funeral removing another piece of intransigent old wood that up until then -- would not bend). ** 7.10.1.3.1.1 states that in combined systems the water supply for sprinklers and an AUTOMATIC standpipe system, “… shall be based on the sprinkler system demand (including any hose stream demand) or the standpipe demand, whichever is greater.” **A: -7.10.1.3.2, partially sprinklered building ** And such a calculation is only required of an automatic standpipe system because a manual is calculated from the FDC and represents a completely separate water supply from the sprinklers. **A: How does a manual calculation from the FDC legitimize the requirement to verify that the automatic water supply meets the standpipe demand? It seems to my old intransigent woody brain, given that if an automatic water supply were proposed, one would then reasonably require a calculation to verify this automatic water source supplied the standpipe demand -- even if there were no manual standpipe calculation. ** And not that anyone asked, but let’s clarify that standpipes are a separate system from sprinklers hydraulically even when they’re combined. (underline added) **A: I and most of your audience know what you mean, but the above sentence "...are a separate system ... even when they're combined" , is logical fallacy at a simple, literal linguistic level. It is realized the explanation is an administrative distinction, not a distinction water flow would make during a fire. It is generous that the intention of the NFPA 14 and 13 committees is shared here. Another logical instance for reflection is created if ---Standard for Standpipes (NFPA 14) wants the designer to go to the Standard for Sprinklers (NFPA 13) to execute this hydraulic calculation per common practice. If a cross-Standard reference is the intention, then why doesn't NFPA 14 Standpipe Standard mention in the main body of text -7.10.1.3.2 that it wants the designer to migrate to NFPA 13 Sprinkler Standard to finish the hydraulics? NFPA 14 -5.4.1.3 is not afraid to explicitly refer the designer to NFPA 13 at its main body of text. When one is designing and using the NFPA 14 Standard for Standpipes at -7.10.1.3.2, it is a logical (even if an unsanctioned Committee practice) assumption to conduct the primary calculation as standpipe system (e.g. 1,250 gpm for a large system in partially sprinklered building) and then supplement the primary calculation with the sprinkler system demand, not the reverse. Your argument is sympathetically heard. But if Standard prose don't go into woody-headed mortals such as myself without accompanying interpretations, we are left to divine, only from the original script that the Standard offers us there. Why would the Standard for Standpipes not clear up this issue and settle the debate? Maybe because the: a. issue is 'very clear' and there is not much to clean up, or b. change doesn't come easy to Committees as well as old guys like me, 1. it is embarrassing to make corrections to one's own writing, especially in the safety industry 2. there is the spectre of liability as past prescriptions might now be opined of inferior quality. In such case, the,Good Samaritan law should apply. as NFPA committee work is far and away well intentioned. c. some committee members make salary from interpreting the very obfuscatory script they sometimes write, or their colleagues write, or their predecessors wrote, and d. NFPA makes money teaching these 'secrets' to denizens at the near and far reaches of their empire where these standard practices have not yet trickled down, or e). it is too difficult for a prescriptive Standard to write out every conceivable instruction for every occasion, and so great-writing is good enough. It is argued that item "e). is wrong and that it is not too difficult to write better than great; it is virtually impossible. With the seemingly unpredictable elements in our lives (at least at the quantum level ;-) we simply can not prescriptively write Standards that will address every situation, let alone write entire volumes without the occasional self-conflict. Writing safety prescriptions is hard to do. That is why intentions should be written too. Intentions should be written into the main text of the prescriptions. But if this happened, would there be as many transactions exchanged on the interpretations and classroom explanations? Taking alternative position to committee opinion is very disconcreting -- there is a tidal surge of branding one is swimming in, and potentially a lot of bank to be losing. BIG THANKS go out to every safety committee member and code framer that offers their time on committee and especially whom share their opinion in public forums such as this one. Steve generously gives of his time and recognized superior expertise, garnered through many months of unpaid contribution to enhancing these safety committees. I am indebted to him for many lessons. Steve, Roland, Ken and the many sisters and brethren like them whom are sharing news we can use on these public forums; they are the exception. Realize most committee members do not ring in when questioned. Scot Deal Excelsior Fire & Risk Engineering gms: +420 722 141 478 GMT + 1
_______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
