METHOD AND DEVICE FOR ELECTRIC CONDUCTIVITY MEASUREMENTS Russian patent published in 1999 - IPC

FIELD: physical and chemical investigations for chemical and associated industries. SUBSTANCE: method involves irradiation of two conductivity cells containing reference and analyzed solutions, respectively, by high-frequency signal of constant amplitude and frequency. Irradiated signal is modulated in amplitude whose instant value depends on electrolyte conductivity. Amplitudes of pulse signal picked off cells is measured; high- frequency signal amplitude is stabilized by maintaining constant the current through cells. Instant values of amplitude of pulse signal picked off cells are measured during every constant-period cycle for which purpose reference signal with linearly growing amplitude is shaped since cycle beginning till end of period. Amplitudes of reference and modulated pulse signals picked off cells are compared, number of these pulses is counted from beginning of cycle till moment of their comparison, and relationship between number of pulses from cells is used to find electric conductivity of analyzed solution. Device implementing this method has counter, two comparators, and microprocessor connected to input of oscillator which is connected to reference- and analyzed-solution holding cells. Counter is connected to oscillator second output. Counter outputs function as data inputs of digital-to-analog converter whose outputs are connected to first inputs of first and second comparators. Second inputs of comparators are connected to inputs of cells and outputs, to microprocessor. EFFECT: reduced measurement error. 2 cl, 6 dwg