Quantitative Determination of Rinsing Effect by Electric Conductivity Measurement

Abstract

A convenient and accurate method of determining the concentration of wash liquor during the rinsing process has been developed by electric conductivity measurement of NaCl solution as a model substance.
Owing to the intrinsic conductivity (173 μ /cm) of tap water, the initial concentration of NaCl has had to be set 2.0%, which shall be reduced to lower concentration if purer water is applied.
As has been reported in previous paper, the rinsing process followed the equation, logC/C₀ = (-1/2.303)·(ν/V)·t
where, C₀ : initial concentration of wash liquor (%).
C : concentration of rinsing liquor at the time t (%),
V : volume of the wash tab (l) .
ν : flow rate of rinsing water (l/min).
The present results were also proved to fit the equation in a model glass apparatus and two electric washing machines of commercially available.
From the water consumption saving point of view, appropriate degree of rinsing has also been discussed.