BN-OF

BN-OF transformer pit covers consist of BN-O type profiles. Flat steel strips 30 x 2 mm are welded to the underside of the sheet metal profile. Both open sides (ends) are closed with flat material. In the event of a fire, it will be temporarily contained within the retention basin until the fire brigade arrives.

 

BN-OF Sheet Metal Profile
material	S 235JR
surface finish	galvanized according to DIN EN ISO 1461
sheet thickness	2.5 mm (2 mm)
module R	62.5 mm
production lengths L	preferably n x R
width B	150, 200, 250, 300 mm
height H	40, 50, 75, 100 mm
edge fold Tu	approx. 10 mm

Simple rules for designing transformer pit covers using BN-OF fire-extinguishing profiles

BN-OF profiles require support on only two sides, always at the ends. However, it is recommended that the bearing for BN-OF profiles be provided around the entire perimeter of the pit to ensure better sealing of the basin. When designing the bearing width for the profiles, the required clearances must be taken into account.

The clearance between the profile and the pit wall in the load-bearing direction should be at least 15 mm on each side; in the non-load-bearing direction, approx. 10 mm per each meter of width. The size of the clearances depends on the basin dimensions, the selected profile arrangement, and their length.

Regarding profile widths, it is advisable to cover the entire area using the standard production widths of 150, 200, 250 and 300 mm, and to distribute any gaps evenly among the individual profiles. For larger quantities, non-standard profile widths can also be manufactured. Regarding profile lengths, when designing a new transformer pit it is recommended to use a multiple of the grid module of 125 mm (this is the most cost-effective option). In the case of an already finished basin or during reconstruction, it is possible to add or subtract 1/4 to 1/2 of the grid module (a less advantageous option with additional costs). Non-standard lengths and widths can also be manufactured; however, this increases the price and extends the delivery time.

The maximum clear spans between supports for pedestrian loading for the respective profile types are specified in the load capacity table.

 

Attachments

Load capacity table for BN-OF profiles (*.pdf)

BN-OF leaflet (*.pdf)