Accession Number : AD0449189
Title : INVESTIGATION OF ELECTRIFICATION OF POWDERS IN FLOW THROUGH TUBES AND NOZZLES. I. A CHARGE ANALYZER
Descriptive Note : Special rept.
Corporate Author : AEROJET-GENERAL CORP DOWNEY CA
Personal Author(s) : Owe Berg, T G ; Fernish, G C ; Flood, W J
Report Date : May 1963
Pagination or Media Count : 46
Abstract : As a part of an investigation of the electrification of powders in flow through tubes and nozzles, a charge analyzer has been designed, constructed, and tested. The charge analyzer has two electrodes at + or - 1000 volts with respect to ground. At a stationary state, the current from each electrode is equal to the rate of deposition of charge. The two currents are recorded and integrated with a planimeter. The electrodes are weighed on a micro-balance for determination of the amount deposited. The nozzle is located at one end of the pair of electrodes. Experiments have been conducted with several airborne powders, in the range 1 to 30 micron of particle diameter, flowing through a hypodermic needle of 0.8 mm diameter and 3 ft length of flow rates between 50 and 500 cc/min. The average positive charge, the average negative charge, and the average absolute charge are proportional to the square of the flow rate. The charge is all acquired in friction between the powder particles and a deposit on the tube wall. Average charges up to 0.01 C/g have been measured. The charge is smaller the greater the extent of agglomeration of the powder. It depends as much upon agglomeration as upon the nature of the powder. It follows that literature data on aerosol charges determined with samples in slow rectified flow, e.g., by a capillary tube or a slit system, are misleading and may be too low by many orders of magnitude.
Descriptors : *POWDERS , VELOCITY , AEROSOLS , AIRBORNE , VOLTAGE , PARTICLES , ELECTRODES , NOZZLES , FRICTION , STATIC ELECTRICITY , CAPILLARY TUBES
Subject Categories : Miscellaneous Materials
Electricity and Magnetism
Distribution Statement : APPROVED FOR PUBLIC RELEASE