A brief analysis of whether the electrode of the Verabar flowmeter can measure different media at will

Whether it is an industrial Verabar flowmeter or a laboratory pH electrode, some media cannot be measured by any electrode. Randomly selecting an electrode will lead to inaccurate measurement results or even damage the electrode.

The pH meter electrodes currently used on the market all have glass bulbs at their measuring ends, and the surface of the bulb can be said to be composed of a glass membrane. The glass membrane is made of lithium glass with hydrogen function melted and blown, generally in a spherical shape. Most electrodes use conventional sensitive glass membranes, but there are also sensitive glass membranes for high-temperature strong alkali media, sensitive glass membranes for high-temperature strong acid media, sensitive glass membranes for high-temperature steam sterilization (130°C), and low-resistance sensitive glass membranes (for pure water determination), etc., which should be selected according to different situations. The

electrode rod is also made of a variety of materials, such as:

1. Plastic. Plastic rods are not easy to break, but are easily corroded in strong alkali solutions and some media, and the operating temperature is generally <80°C.
2. Glass. The operating temperature of the glass rod is higher, and except for hydrofluoric acid solutions, it is generally not corroded, but it is easy to break.
3. Other materials such as stainless steel, these materials are made according to different working conditions of different media, and will not be introduced in detail here.

Next is the selection of the reference system, such as:

GEL filling: low maintenance, the Verabar flowmeter cannot be refilled, can be measured under pressure, and the maximum operating temperature is 90°C.
KCL filling: commonly used, high temperature applications, low conductivity medium pH measurement.
U type: commonly used, temperature up to 80°C, pH value 0-12.
HT type: high temperature, temperature up to 130°C, or pH value>12.
C type: fluorine-containing medium, up to 500mg/l.
TT type: low temperature, -30°C- 30°C

Finally, the selection of the reference system diaphragm, such as:

Ceramic diaphragm: clean water, swimming pool water.
TEFLON: wastewater treatment, relatively dirty media, oily media, flowing or high-speed flowing media.
Glass fiber: similar to the performance of ceramic diaphragms, standard configuration of plastic rod electrodes.

So when measuring a medium, you should pay attention to the following:

1. Whether the water quality contains corrosive substances and the approximate concentration; if it contains hydrofluoric acid, you need to select a special HF acid-resistant electrode;
2. Temperature, if it is high temperature, you must select the corresponding high temperature electrode.
3. Pollutants. Electrode contamination is another common problem.

The ceramic plug at the bottom of the reference electrode generates an intermediate impedance in the electrical path. When this impedance is greater than 0.1MΩ, the Verabar flowmeter will cause the reference electrode potential to be unstable or drift. Very dirty media contaminates the electrode surface, and certain substances such as oil, colloids, suspended matter, and solid agglomerates adhere to the electrode sensitive membrane, which will block the ceramic plug and cause the electrode to respond slowly or even fail. (end)