E-mail: michael@shboqu.com   |   Expert in Water Quality Measurement and Water Treatment Project

How to deal with several common problems of online conductivity meter?

by:BOQU     2023-04-09
The online conductivity meter is a multi-range instrument that can meet the detection requirements of various applications from deionized water to seawater. The instrument provides automatic temperature compensation and can set the temperature coefficient, so it can be used to measure liquid samples with a different temperature coefficient than water. It can provide three ranges and has automatic range selection function, which can automatically select the appropriate range during detection. The instrument is supplied with a dual-plug stainless steel conductivity electrode with built-in temperature sensor (for automatic temperature compensation), a rubber non-slip cover, 4 alkaline AAA batteries, the instrument operation manual and a soft carrying case. How to deal with several common problems of online conductivity meter? 1) Can online measurement replace offline measurement? Is there any need to believe in the results of on-line measurement when the sensor technology—conductivity sensor is so mature today? It is necessary to measure the conductivity after sampling the pharmaceutical water. The point of view is that the conductivity meter technology is very mature, and the supplier has the ability to ensure that the battery constant is within a certain error range. Even if the offline conductivity meter has a daily so-called calibration, this frequency is not performed every day in most cases. The online conductivity meter may be troublesome in daily calibration, but since the online monitoring technology is selected, the online test results should be believed, and appropriate standards should be established, and automatic feedback will be automatically performed through automated means. Additional sampling for offline testing is not necessary. Too much necessary. 2) The conductivity limit of purified water at 25 degrees is 5.1 μS/cm, is it appropriate? Has the capacity of the existing water production equipment far exceeded this design requirement, and the linear conductivity limit curve of purified water is also unreasonable. It is recommended to use the USP three-stage method, a stepwise conductivity limit of a broken line segment Curve, as the standard of limit judgment. 3) Is the linear interpolation method necessary for the calculation of the conductance limit of purified water, is the conductance value of water for injection corrected to 25 degrees, and the limit under 25 degrees is used to judge whether it exceeds the standard? At the same time, since the temperature of water for injection is usually much higher than 25 degrees, many conductivity meters have built-in calculation methods to convert it to the conductivity at 25 degrees. In Mr. Zhang’s opinion, this is not necessary, and can be directly based on the above figure A curve below to make a judgment. The standard practice for measuring conductivity should be to adjust the water sample taken offline to 25 degrees by means of a water bath, etc., and directly measure its conductivity instead of converting it by temperature.
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