Fire Ring Research Articles

Interest group standards for ecological impacts at wilderness campsites

Abstract Little research has focused on the ecological standards of recreation interest groups for campsites in wilderness. Because there are differences in their use of the resource, it is sometimes assumed that groups’ standards for campsite impacts are also different. Using evaluations of bare ground and fire rings from organized interest groups, this study compares impact standards for outdoor activity clubs, environmental organizations, and wilderness managers. For the impacts and groups studied here, results suggest that groups using the back country may not be as different in their views as generally assumed, managers’ standards generally differ from those of user groups, tolerance of ecological impacts at campsites is generally high, and ecological impacts may not be a high priority for users when compared with other campsite attributes. Findings imply that some consolidation of group types may be appropriate for campsite management purposes. Analysis of group standards can help identify a range o...

REFRACTORIES UNDER LOAD CONDITIONS1

Life factors.—The life of fire clay slabs, rings and saggers is influenced by a number of factors, both mechanical and chemical. The chief factors controlling the life of the slabs are (1) proper selections of clays and grog, (2) medium absorption or porosity, (3) strength in the unburned state, (4) proper and thorough blending and preparation of the mix, (5) proper pressing so as to insure freedom from flaws, (6) proper drying, (7) proper setting in the kilns and especially (8) initial burn. These factors are briefly discussed. Setting.—The manner of setting grinding wheels, using large slabs is described. This manner of setting causes transverse bending stress to be set up in the slab and shear stresses to develop. This shearing force, in connection with the large size and the high temperature (cones 11 to 12), make severe conditions for the slab to withstand. Shape and size.—The rate of heating and the size and shape of the slabs are additional factors. Round slabs, up to about 20° in diameter have a decidedly longer life when made in two half sections as compared with the solid shape. Larger slabs have longest life when split up into four sections, while if solid they will fail in one burn. Warping of the slabs, as well as cracking, causes failure. In general, if the width of area of the load is held constant, and length of span of the slab is increased, deformation and cracking is slightly increased. If the span is held constant, and the width or load area is increased warpage is greatly increased, especially as the number of burns under load increases. Cracking also increases in direct proportion to increase in width. These features are more pronounced the longer the span. Ultimate failure at high temperatures.—When not due to structural defects, failure is brought about by a gradual decrease in mechanical strength from burn to burn, so that fire-clay slabs under transverse load at such temperatures have decided limitations