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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