Rationale

The current direct flame impingement test configurations (vertical and horizontal) of the ASTM 2886 (based on E2912) is not representative of heat exposure for exterior vents. The horizontal vent sample is currently placed too close to the burner, giving an excessively fuel rich area near the sample surface, causing flames to shoot out the back end of the table. The vertical vent sample has flames that go up the box, but it is difficult to confirm that flames are actually impinging on vent sample. Comparative heat fluxes between the two orientations showed the vertical orientation having a heat flux roughly four times higher than the horizontal orientation, which would not be observed in an actual exterior fire event (e.g., direct flames impinging on the underside of a horizontal vent [soffit vent] will experience higher heat flux than a vertical vent situated on a wall [gable/foundation vent]). The proposed change, at least in the view of the technical contact, would be to have a burner/wall/vent configuration to follow a combination of E2707 and E2957 test standards.