| 摘要 |
<p>1,111,410. Determining porosity. GEORGIA TECH. RESEARCH INSTITUTE. March 20, 1967, No, 12862 / 67. Heading G1S. In apparatus for determining the porosity of a specimen 10 of porous material by gas displacement, the specimen is sealed in a flexible envelope 11 which is closed at the bottom by means of a base B which is screwed into a cavity 22, there also being provided a reservoir to hold the gas and valve means 30, 31, 34 to selectively release the gas from the reservoir into either the envelope or the cavity. In use, a pump P is used to evacuate air from within the envelope 11 and the cavity 22, valves 30, 31 are then closed and valve 34 opened allowing air in the column 35 to expand into the cavity 22 so that the envelope 11 adheres to the specimen. The levelling bulb 37 is then raised to bring the pressure in the cavity to atmosphere, the pressure difference being read on scale 44 of a manometer M as a measure of the bulk volume of the specimen. Valve 30 is then opened and the charge in pressure due to air filling the pores of the material is measured on the pore volume scale 45 of the manometer when atmospheric pressure is reestablished. In a modification the manometer is replaced by a comparison chamber and pressure gauge. In a further modification, the specimen and envelope are sealed in a chamber of variable volume which is controlled by a sealing disc moved by a rotatable shaft. In a further arrangement the variable volume chamber is connected through valve control means to a similar control chamber.</p> |
