Fluid density measurements by means of gamma ray absorption

The paper discusses the phenomena involved and the parameters controlling the usefulness of a method of measuring the specific gravity of liquids flowing in a pipe (during manufacturing processes), and of detecting the interface between liquids having different specific gravities, e.g. petroleum products. To ensure stability and accuracy a pressurized ionization chamber is used in conjunction with a vibrating reed electrometer, and a heavily shielded gamma source of the order of one curie. Changes in specific gravity of 0.2% of liquids in steel walled pipes of up to 14 inches diameter have been detected. Details are given of typical industrial installations.