Abstract: A method of cooling a block of porous material comprising inserting said block into a chamber, subjecting the chamber to air pressure less than that of the ambient air and inserting means into the said block to induce a flow of cooling air through the interior of the block to the said chamber, whereby the lower pressure in the chamber causes the cooling air to flow inwardly through the means inserted in the block for cooling the block.

Abstract: Means to induce a flow of air from the interior to the exterior of a block of porous material; comprising a chamber adapted to house said block and to be maintained during an operative cycle at an air pressure less than ambient air pressure; means to locate and to grip the block within said chamber; an injector needle assembly including an injector needle adapted to penetrate the said block after it has been located by the said gripping means; and means to move the injector needle into said block to allow air to flow through the said needles into and through the said porous block.