There seems to be a common misconception concerning the official status of FM guidelines. NFPA is an adopted Standard which in most if not all jurisdictions is part of the legally adopted building code. When adopted as part of the code it is part of the law of that state or local jurisdiction. Any code official who's worth anything will tell you that his duty is to uphold the laws of his state when it comes to building and construction. (Ok, in a perfect world, go with me on this)
FM Data sheets are tremendous tools and are used by many to determine protection criteria for those special systems that the Codes do not always address. BUT, the FM data sheets are not part of the building code. They can be used as an addition or supplement to the basic NFPA Standard but they are the guidelines from an insurance entity. The FM recommendations are typically negotiable between the insurer and the owner, Code requirements are usually non-negotiable (there are variances for certain things). I don't know of any building official that will tell you to use FM in place of NFPA. An insurance underwriter would be the one to tell you if they have recommendations beyond NFPA which they would require/request. In no way am I discrediting the FM data, it is priceless but it is not the same as NFPA from a legal standpoint. Anyway, back to the main topic................. Check out the commentary in FMDS 7-11. It addresses the air flow issue. Craig L. Prahl, CET Fire Protection Specialist Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [email protected] http://www.ch2m.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Jay Jay Blocker Sent: Tuesday, February 03, 2009 11:21 PM To: [email protected] Subject: Re: Sprinkler protection below conveyors in pits Well yes and noon the interlock issue but thats not really the issue at hand. In order to find out if FM or NFPA is going to be the standard I would consult the AHJ to get the perspective of the individual that says yes or no. I have yet to find an AHJ that says FM will be used to substitute NFPA simply due to liability. If not listed for there intended use just simply ask the AHJ to sign off on it then the situation is resolved. If they will not sign off on that look at the deluge system. Mines are a creature all there own and rarely found to resemble the next. The main reason for this is do primarily to the length of the conveyor and type of material it transports. As far as the interlock goes we all know how the fire tetrahedron works. The stopping of the belt is not so the fire wont outrun the sprinklers it is to limit air flow which is fueling the fire. The fire can only out run the sprinklers if the proper fuel base is there, so we limit the extra ingredients. Keep us informed. Jeremy S. Blocker Let us not look back in anger, nor forward in fear, but around in awareness. --James Thurber ________________________________ From: Rod DiBona <[email protected]> To: [email protected] Sent: Tuesday, February 3, 2009 8:44:28 AM Subject: RE: Sprinkler protection below conveyors in pits Well I have a different opinion on this Craig. Most of the time the ONLY reason that many of these industrial sites are getting any fire protection is because the insurer is asking for it. We have about seventy mining sites in our working area and the majority of them have very little or no protection at all. When the insurer is the one coming in and ASKING the owner to sprinkler a certain hazard he is also the one telling them how it will be done to receive the proper premium credit. I have had several instances in the last year dealing with this exact issue. On one of the projects where the sprinkler alone was $10 million I adamantly asked that we cover the top and bottom belt on thousands of feet of new belts that were being built. I showed NFPA 15 and even had a proposal that showed that it was even more important with Powder River Coal because of its higher propensity to spontaneous combustion. This was a piece done by the powder river coal group. At the end of the day the engineers said no because FM was not requiring it. Their data sheets only require the top belt. It is one of the few times that I have seen where the FM data sheets were clearly less restrictive than NFPA. Secondly most of these systems that I have seen are not deluge. This is due to hydraulic restrictions of large deluge systems and physical restrictions due to parallel runs of bulk needed for several deluge systems. Most of these systems are preaction that I have seen. As you referenced there is an interlock that shuts down the conveyor upon activation isn't that so that the fire doesn't "out run the sprinklers." Rod DiBona Rapid Fire -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, February 03, 2009 6:56 AM To: [email protected] Subject: RE: Sprinkler protection below conveyors in pits First, Unless FM's guidelines exceed NFPA I wouldn't be replacing the NFPA standard with the FM guidelines since NFPA is usually referenced in the building codes and FM's Data Sheets are not. So if NFPA says do top and bottom and FM says only do bottom I'd be doing top and bottom. Second, Conveyor system protection is found in more detail in NFPA 15 (7.2.3, 2007) since these are almost always deluge type systems. Definitely would not want to use closed heads in this application as the fire could out run the sprinklers or the sprinklers may not respond at all due to the belt movement. A typical installation would consist of open spray nozzles usually with a broad angle spray pattern with linear heat detection or other heat detection method to set the system off. Manual activation is also a common accessory to the system. Also it wasn't stated what was being conveyed. There are other NFPA Standards for various industries or hazards which provide additional information on protection of conveyors in specific applications. With open nozzles such as Tyco's Protectospray or Reliable's Model A or Viking's Model E or other similar, you can select the discharge angle up to 180 degrees, the nozzle can be placed with a few feet of the object you are protecting with no loss of integrity of the spray pattern. This is something you can not accomplish with a typical SSU or SSP. They are not made for this type of application. You must determine the appropriate spray angle as you determine the distance between the nozzle and the belt (axial distance). As you get closer to the belt naturally the spray pattern area will get smaller. Also understand that you have various K-factors to choose from. Choose the correct K-factor nozzle to deliver the needed amount of water to the hazard. You do not need to use just 5.6K's everywhere. If this is an enclosed conveyor make sure the structural people as well as the conveyor mfgr. know about how much water you will be introducing into the enclosure so they can provide adequate drainage capabilities. Remember if you go below a certain size orifice (I think it's 3/8") you will have to provide a strainer on the system. Don't forget to discuss system interlocks for belt movement interruption with the conveyor vendor and owner. Craig L. Prahl, CET Fire Protection Specialist Mechanical Department CH2MHILL Lockwood Greene 1500 International Drive PO Box 491, Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 [email protected] http://www.ch2m.com -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Rod DiBona Sent: Monday, February 02, 2009 6:49 PM To: [email protected] Subject: RE: Sprinkler protection below conveyors in pits We have used nozzles that can be selected with various spray patterns in this situation. Also something that we have recently discovered is that if this is an FM insured property they normally do not require the return belt to be covered even though NFPA is clear that it should be. If not FM then we find a solution that most closely complies the standard and listing and present that to the powers to be. It is not always possible to comply 100%. Rod DiBona Rapid Fire -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ryan Hinson Sent: Monday, February 02, 2009 3:56 PM To: [email protected] Subject: Sprinkler protection below conveyors in pits Where would I go to properly protect below conveyors in pits that there is less then 4' of clear space below the return loop of the conveyor and the conveyer belt is 60" wide with SSU's? NFPA 13(2002) section 8.6.5 does not address this situation in my opinion. What is the space depth at which sprinklers are no longer able to develop the water pattern necessary to be practicable? Thank you, Ryan L. Hinson, EIT, CET, Nicet III FP Design Manager Fire Construction Design Services, LLC #C124 A Division of Fire Construction Services, Inc. 6950-43rd Avenue SE St. Cloud, MN 56304 Direct: 320-250-5404 Fax: 320-358-3495 email: <mailto:[email protected]> [email protected] CONFIDENTIALITY NOTICE: The information contained in this message, including any files transmitted within, is confidential, may be legally privileged, and is intended only for the use of the individual(s) named above. The use of any confidential or personal information may be restricted by state and federal privacy laws. 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