Combustion Shaft Test

A building material is rated into the group Bl if (a) it passes the Combustion Shaft Test as described in the standard DIN 4102 Teil 1, 1981 and (b) it also meets the requirements of group B2. 

The combustion shaft is a vertical heat-insulated shaft containing metal frames for mounting 4 specimens of 190 mm x 1000 mm with a maximum thickness of 80 mm. The specimens are suspended so that they form a vertical chimney with open edges. A square 32-hole gas burner is situated inside the chimney, somewhat above the lower ends of the specimens, and supplied with 35 dm /min of methane and 17.5 dm /min of air. During the test period, 10 m /min of air is introduced into the combustion shaft at 20 °C and the temperature of the combustion gases is measured by thermocouples in the stack. 

In Hungary, the rating of combustible building materials is similar to that in FRG but a class of medium ignitability is also defined. If a building material is tested in the combustion shaft (according to MSZ 14800/4-74) under identical conditions to DIN 4102, the specimen should pass the test with a 2-min exposure to the flame otherwise it is rated as easily ignitable . 

In pulverized coal combustion, the abrasiveness of the particles severely limits the Kfe of the pulverizer grinding elements. The Abrasiveness Index in this application is usually determined by the Yancey-Geer Price apparatus (Babcock and Wilcox, 1992). In this test, four metal test coupons attached to a rotating shaft are rotated at 1440 rpm for a total of 12,000 revolutions in eontact with a sample of 6350 pm x 0 (0.25 in. X 0) coal. The relative Abrasiveness Index is then caleulated from the weight loss of the coupons. Babcock and Wilcox has estimated the wear of full-scale pulverizers on the basis of the Yancey-Geer Price Index. 

---