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Chemical Industry

Plastic Magnetic Level Indicator Applied in Concentrated Hydrochloric Acid Liquid Level Measurement

Hydrochloric acid or muriatic acid is a colorless inorganic chemical system with the formula HCl. Hydrochloric acid has a distinctive pungent smell. Concentrated hydrochloric acid  is a colorless to yellowish pungent liquid. It is highly corrosive but noncombustible. Soluble in water, alcohol, and benzene.

Chongqing Jianshe Automobile Air Conditioner Co., Ltd. is a manufacturer with an annual output of 80 thousand air conditioning compressors. In the concentrated hydrochloric acid (36-38.0%) auxiliary material tank. Hydrochloric acid is corrosive, and concentrated forms release acidic mists that are also dangerous. If the acid or mist come into contact with the skin, eyes, or internal organs, the damage can be irreversible or even fatal in severe cases, so it is usually packed in closed opaque containers or tanks. To avoid accidents caused by hydrochloric acid overflow, it is necessary to monitor the liquid level in real time with reliable liquid level measuring instrument.

Liquid level instruments commonly used in the market include float level indicator, ultrasonic level transmitter, radar level meter, magnetic level indicator, etc. Base on the strong corrosive characteristics of concentrated HCl, the advantages and disadvantages of the instruments are compared as the following table:



Measured method

Strong corrosive application

Float level indicator

Due to magnetic effect, as the float moves, proximal reed switches in the float level indicator are magnified.


Float and guide tube are coated with acid and alkali resistance, so the cost increases and the price also rises accordingly.

Ultrasonic level transmitter

 Reflected wave is received by the transducer and converted into an electronic signal.


Need corrosion-resistanttransduce. Only suitable for open pool and non-volatile medium.

Radar level meter

 High frequency waveguide theory.


Need corrosion-resistant probe,not interfered by environment. Accurate measurement but high price.

Magnetic level indicator

Equilibrium in U connected vessels and magnetic coupling effect.


Various buoys and flanges are available for different applications. Wide range application, including corrosive condition, easy installation and economical.

From the above comparison, it is clear that magnetic level indicator is an ideal choice for concentrated HCl level control. The client has tried most above instruments except magnetic level indicator, with high cost but dissatisfied result due to the strong corrosivity and volatility of concentrated HCl.

Plastic Magnetic Level Indicator Applied in Concentrated Hydrochloric Acid Liquid Level Measurement

After contact with Jiwei, the client had a detail communication with the engineer. At first, Jiwei engineer recommended Flap-11Px Lined Magnetic Level Indicator, which is suitable for most strong corrosive liquid medium and the chamber is made of 304 stainless steel lined with F4 (PTFE)/F46 (FEP) for strong corrosive liquid level measurement. However, the concentrated HCl storage tank is made of anticorrosive plastic, which is difficult to mount high weight instrument, and the metal process connection also has leakage risk under such strong corrosion. As result, Flap-11C Plastic Magnetic Level Indicator is a better selection. Flap-11C is made of high-quality PP material and has stronger anti-corrosion performance. It is a commonly used corrosion resistant level meter. With the same measuring range, its weight is only about 1/5 of the standard model Flap-11A, which greatly facilitates the installation. More importantly, the flange is made of anticorrosive plastic material, so no corrosion leakage concern.

Flap-11C Plastic Magnetic Level Indicator is not limited by the tank height, and the mechanism of display panel is completely isolated from measured medium. The excellent sealing technics, high reliability, and high cost performance ratio have convinced the client. Compared with the similar products of other brands in the market, our Flap-11C Plastic Magnetic Level Indicator series products have the following advantages:

● Lightweight and easy to install, only about 1/5 weight of the similar product that made of stainless steel.

● Made of high quality material PP, stronger corrosion resistance.

● Display panel with broader design,greatly increases the visual distance and viewing angle, With larger sharp scale and digits, the indicator appears beautiful and elegant outlook.

● Level of Ingress Protection exceeds national standard IP54, IP65 and IP66/IP67 are available for different applications.

● Accessory magnetic switches and remote transmitters have been explosion protection certified for both Flameproof Enclosure and Intrinsically Safety.

From the feedback, all Flap-11C Plastic Magnetic Level Indicators have been running stably and reliably without any problems. The outstanding performance of Flap-11C in the level measurement of concentrated hydrochloric acid is beyond the client’s expectation, so he planned to purchase another batch for the next project.

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