Can ESFR Be Used for Extra Hazard Group 2?
ust before I saw that discussion on the forum I was confronted with a nearly finished, similar situation. A new technical plant for manufacturing of large-diameter high voltage cables. Huge amount of PE in the next-to-outer layer, and the sprinkler designer have based the fire protection on ESFR due to ‘’all the plastics’’ and generally large ceiling heights – variation between 40 and 55 feet – and a wish for ‘’maximum flexibility’’, by using table values for UUP for the respective ceiling height. NFPA 13 – 2019 is to be used for the design. The manufacturing process starts with a thin single wire and ends in an obvious UUP commodity. In my mind this is mostly a production risk to be protected with spray sprinklers and density/area calculations, or CMSA-sprinkler parameters where the ceiling height permits it, especially as most of the fire load is moving cables, without automatic stop because the alarm could be undesirable or false. It was said that cables during production would be directed up towards the ceiling, turn and twist on large diameter wheels, and also have large horizontal stretches before they run down into the next machine that may put on a new metal screening or extruding the outer PE layer before PVC or similar outer layer. Obviously a multi-stage production that in the end makes one large cable from 3 or more smaller cables. As I have seen in earlier discussions, the understanding of the text in chapter 23.1.1 saying ‘’ESFR sprinkler shall be permitted to protect : …. Any storage arrangement OH1, OH2, EH1, and EH2 design criteria’’ must be vital for the understanding. I don’t feel the actual situation is a storage arrangement, but if so, what is the target for the wording design criteria? I suspect there will be ‘’longitudinal flue spaces’’ between the cables, transvers flue spaces are not possible. Some places there will be cable(s) in conflict with the minimum 300 mm horizontal distance from a storage suppression sprinkler rule. However, this is the first time I have been presented for a ‘’ceiling only’’ option with 1 or 2 intermediate levels ESFRs having water shields. And (luckily !?) someone had found the FM DS 8-9 Table 17b and put in K 480 storage sprinklers in the part of the manufacturing building with the highest ceiling. Hopefully this is not the only cable manufacturing plant in the world, and I would greatly appreciate other views on this subject. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
4 Comments
Pete H
5/19/2023 06:49:07 am
I see where you were going with this, at first I also thought:
Reply
Jesse
5/19/2023 09:14:24 am
The short answer is, no ESFR is not intended for occupancy hazard classes EH1 and EH2.
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Anthony
5/19/2023 10:02:39 am
As Jesse and Pete have mentioned storage is not the same as production. Production has a different set of hazards as compared to storage. Specifically the area required to be protected.
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Franck
5/19/2023 10:13:02 am
As ESFR are extremely good at protecting storage activities (when adequately designed), they might not be suitable for some production activities. This is why it has been excluded, for example, with EH Gr 1 & 2.
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