Rack Storage Flue Space and Beam Length
Checks the transverse gaps a bay actually provides, the beam length the nominal flue requires.
Example
You enter
- Pallet width across the bay (in) 48
- Load depth into the rack (in) 48
- Pallets per bay 2
- Transverse gaps in the bay 3
- Nominal flue width (in) 6
- Beam length as built (in) 108
- Rack frame depth (in) 42
- Back-to-back frame spacing (in) 12
- Deeper load being considered (in) 52
You get
- Transverse gap each bay provides 4.0 in across 3 gaps -- 67% of nominal
- Beam length the flue requires 114 in, 6 in longer than built
- Beam shortfall (in) 6
- Overhang at each face 3.0 in
- Longitudinal flue 6.0 in -- meets nominal
- With the deeper load 2.0 in at 5.0 in overhang -- 33% of nominal
- Deeper load flue share (%) 33.3333
Details, formula, and sources
Checks the transverse gaps a bay actually provides, the beam length the nominal flue requires, and the longitudinal flue left after pallet overhang. A bay sized to fit its pallets gives 4 in where 6 in is nominal, and a deeper load closes the back-to-back flue to a third. NFPA 13 as adopted governs.
Required beam length = pallets x pallet width + transverse gaps x nominal flue; longitudinal flue = back-to-back spacing - 2 x overhang, with overhang = (load depth - frame depth) / 2.
NFPA 13 Standard for the Installation of Sprinkler Systems as adopted, with the commodity classification, storage height, and arrangement.
NFPA publishes its standards for free read-only online access; the nominal 6 in transverse and longitudinal flue is stated there.
Estimate. AHJ and licensed professional govern.
Field names used by the API: pallet_width_in, pallet_depth_in, pallets_per_bay, transverse_gaps, nominal_flue_in, beam_length_in, frame_depth_in, back_to_back_spacing_in, deeper_load_depth_in, transverse_gap_each_in, required_beam_length_in, beam_shortfall_in, pallet_overhang_in, longitudinal_flue_in, deeper_load_longitudinal_flue_in, deeper_load_flue_share_pct
- Nominal flue 6 in transverse and longitudinal unless the adopted edition and arrangement say otherwiseNFPA 13 as adopted
- In-rack sprinklers required when ceiling protection cannot be shown adequate; that determination is the fire protection engineer's and the AHJ'sNFPA 13 as adopted