GB1363663A - Porosity measuring apparatus - Google Patents

Abstract

1363663 Porosity measuring apparatus A T H A KHAZRAJI 23 Aug 1972 [17 June 1971] 28469/71 Heading G1S The apparatus comprises, a test chamber 6 adapted to contain a porous sample 8 held compressed by a screw down lid 4 and a pressure block 7, a valve 2 in a graduated tube 3, a further graduated tube 12 connected with a flexible pipe 11 and a mercury reservoir 13, a valve 14 connecting either to an air pump 15 or to atmosphere or a vacuum pump 17 via a further valve 16. In operation the valve 2 is opened to the atmosphere and air under pressure is provided via valve 14 to the mercury reservoir 13. This pressure drives the mercury from the reservoir into the test chamber 6 which is empty except for the block 7 and up the tube 3 to a predetermined mark. A volume reading is then taken on the graduated tube 12 near its bottom, the graduations reading zero at the reservoir and mounting as the tube descends. This volume reading represents the bulk volume of the test chamber 6. The valves are now released to atmosphere and the sample 8 introduced into the chamber 6 which is tightly closed. The entry of the mercury into the chamber 6 and up to the mark on the tube 3 is repeated and another reading taken on the tube 12, this time near its top. The difference in the two readings gives the bulk volume of the test sample. Now the air pressure is increased to raise the mercury to a level just above the valve 2 which is then closed. Valve 14 is then released to atmosphere and valve 16 turned to connect the reservoir to vacuum. The mercury rises again in the reservoir bulb 13 until it comes back to a marked level when under atmospheric conditions. The valve 14 is now turned to an isolated position where it communicates with neither 15 or 16, and the air in the sample 8 is allowed to leak out into the chamber 6 and the tube 3. The valves 14 and 16 are then turned to atmosphere so that the mercury rushes back into the chamber 6 and submerges the sample again, driving the exuded air from the sample into tube 3. The chamber 6 is now moved vertically until the mercury levels are equal in both tubes and the pore volume or volume of the exuded air in tube 3 may be read. The porosity may now be simply calculated as a percentage of the original bulk volume of the sample corrected to allow for a volume of adsorbed air on the sample surface.