Abstract: An apparatus and method for measuring the density of a low density medium ch as air by measuring the absorption of radioactivity decay particles such as alpha particles in the air. The apparatus includes a source of alpha particles from which the alpha particles are directed to the air sample to be measured. An alpha particle detector is spaced from the source by a path distance which traverses the air sample. The detector is located at an operating point which corresponds to the path distance where one half of the emitted alpha particles are detected. A control system employs a double sideband, suppressed carrier waveform generator which supplies a double sideband, suppressed carrier as a reference signal and supplies a double sideband, suppressed carrier waveform that is modulated by the detection signal.

Abstract: The present invention provides a process for separating a condensable gas from a non-condensable gas by switching at least three adsorber beds which preferentially adsorb the condensable gas serially through the following steps:(a) an adsorption step in which a mixture of the condensable and non-condensable gases are passed through the bed and the separated non-condensable gas is withdrawn therefrom;(b) a supercharging step in which a stream relatively rich in the condensable gas is passed through the bed, the stream having an actual volume at least three times that necessary to displace a void volume of the bed;(c) a desorption step in which a vacuum is drawn on the bed and an amount of a non-condensable gas is bled through the bed;and wherein the non-condensable gas in conjunction with entrained condensable gas from step (c) is passed into a vacuum pump, is compressed, at least some of the condensable gas is condensed and at least part of the non-condensable gas and remaining condensable gas is the passed t

Abstract: A method of drying hydrated crystalline magnesium sulfate to reduce its surface moisture content is disclosed. The method comprises: (a) fluidizing a bed of hydrated crystalline magnesium sulfate particles by continuously passing a heated gaseous medium in a generally upwardly direction through the particles at a superficial velocity at least sufficient to maintain turbulent fluidization and mixing of the particles throughout the bed; (b) transferring a dispersed form of hydrated crystalline magnesium sulfate to be dried into the fluidized bed; (c) maintaining the amount of crystalline magnesium sulfate within the fluidized bed at a constant depth; (d) controlling the temperature and relative humidity of the heated gaseous medium to maintain a bed temperature and humidity sufficient to vaporize at least a portion of the surface moisture from the hydrated crystalline magnesium sulfate without removing waters of hydration; and (e) removing dried hydrated crystalline magnesium sulfate from the bed.