C/VM2 sez. for radiation calcs…
The design fire for this scenario comprises an assumed emitted radiation flux from unprotected areas in external walls of the fire source building (assuming no intervention). This shall be taken as:
d) 58 kW/m² for FLED for sprinklered firecells not containing a storage occupancy or a storage occupancy with a capability to store to more than 3.0 m
Is my reading of this correct that 58kW/m2 (733 degrees) should be used for all sprinklered fires, or is the intent that it is only for non storage occupancies or where storage is less than 3m. In that case, what radiating output/ temperature should be used? If it is the sprinklered temperature, may as well take the sprinkler system out completely, as that will pay for the hundreds of thousands of dollars of extra concrete walls due to the lesser unprotected area allowed.
Some common sense thoughts
- If you plug in some of the numbers in the C/VM2 tables and apply CVM2 allowances for unprotected area, you get more or less the 58kW/m2. Given it is a deemed to comply acceptable solution, the same values should be used for consistency given there is a single Building Code
- From the reply from the NZFS to my query, it does not appear that fire spread from sprinklered buildings is an issue and hence it is not a significant problem that needs a large safety factor.
see https://fyi.org.nz/request/3885/response/12918/attach/5/OIA%202016.815%20Response.pdf. This is backed up by some stats I had from overseas, such as FM Global. interestingly enough in the (US) stats, the age of the sprinkler system didn’t make much difference, whcih is unexpected, as modern storage sprinklers have more science to them than the older systems such as the small bore C/UP heads of NZS4541P.
I know MBIE are looking at rewording this in the new-and-improved VM, but that doesn’t help in the short term