In industries such as chemical processing, chlor-alkali production, fine chemicals, lithium battery materials, and wastewater treatment, storage tanks containing highly corrosive media such as hydrochloric acid, sulfuric acid, sodium hydroxide, liquid chlorine, and bromine water require highly reliable level measurement solutions.
Failure of a level instrument caused by corrosion may lead to inaccurate measurement, production interruptions, leakage of hazardous chemicals, and even serious safety or environmental incidents. Therefore, selecting a reliable corrosion-resistant level measurement device is essential for ensuring safe and continuous industrial operation.
To address these demanding applications, Jiwei Automation has developed the Flap-11Px Lined Magnetic Level Indicator, a specialized level measurement instrument designed for highly corrosive environments. With advanced PTFE (F4) and FEP (F46) lining technology, the product provides excellent corrosion resistance and reliable liquid level monitoring for chemical storage tanks and process vessels.
Project Background
A large fine chemical manufacturer operates multiple storage tanks containing highly corrosive materials, including:
- Concentrated sulfuric acid tanks
- Hydrochloric acid tanks
- Sodium hydroxide solution tanks
- Sodium hypochlorite tanks
The production process requires continuous and accurate monitoring of liquid levels under harsh chemical conditions.
The company required a level measurement solution with the following capabilities:
- Continuous real-time level indication;
- Clear local visual display;
- Remote signal transmission to DCS/PLC systems;
- Long-term resistance to aggressive chemical corrosion;
- Low maintenance requirements;
- Compatibility with hazardous and explosive environments.
Previously, conventional stainless-steel magnetic level indicators were installed on some tanks. However, after several months of operation, corrosion occurred on wetted parts, and leakage appeared around flange connections. Frequent replacement and maintenance increased operational costs and safety risks.
Analysis of Operating Conditions
After detailed investigation, engineers identified several key challenges.
1. Extremely Corrosive Process Media
Hydrochloric acid, sulfuric acid, sodium hydroxide, and other chemical liquids can severely corrode ordinary metal materials.
Although stainless steel such as 304 and 316L offers certain corrosion resistance, long-term exposure to high concentrations of strong acids or alkalis may still result in:
- Pitting corrosion;
- Crevice corrosion;
- Material degradation;
- Leakage failures.
Therefore, conventional metallic level gauges cannot always meet the requirements of these applications.
2. Flange Connections Are High-Risk Leakage Areas
Many traditional anti-corrosion level indicators use simple plastic lining methods on the float chamber.
However, the connection between the float chamber and flange is often the weakest point. Mechanical stress during installation or thermal expansion during operation may damage the lining layer, resulting in chemical penetration and leakage.
This was also the primary failure reason for the previous equipment used by the customer.
3. Requirement for Remote Monitoring
The customer’s central control room needed real-time liquid level data.
Therefore, the selected level indicator needed not only local indication but also:
- 4–20 mA output;
- Connection with PLC/DCS systems;
- High and low-level alarm functions.
Solution: Flap-11Px Lined Magnetic Level Indicator
After technical evaluation, the customer selected the Jiwei Flap-11Px Lined Magnetic Level Indicator as the replacement solution.
Designed specifically for corrosive applications, the Flap-11Px adopts a corrosion-resistant lining structure using:
- PTFE (F4) lining;
- FEP (F46) lining.
These materials provide excellent resistance against strong acids, alkalis, and other aggressive chemicals.
Based on different operating media, suitable lining materials were selected:
| Storage Medium | Recommended Lining Material |
|---|---|
| Concentrated Sulfuric Acid | PTFE (F4) |
| Hydrochloric Acid | PTFE (F4) |
| Sodium Hydroxide | PTFE (F4) |
| Liquid Chlorine | FEP (F46) |
This customized selection ensures both corrosion resistance and long service life.
Key Advantages of the Lined Magnetic Level Indicator
1. Advanced Lining Structure Prevents Leakage
One of the major advantages of the Flap-11Px is its optimized lining structure.
Unlike conventional lined level gauges, Jiwei’s design improves the connection between the lining layer and flange structure, reducing the risk of cracks caused by installation stress or mechanical deformation.
This effectively minimizes the possibility of corrosive media contacting the metal body and significantly improves operational safety.
For chemical storage applications, this design provides a more reliable solution for long-term operation.
2. Excellent Compatibility with Various Corrosive Media
Different chemicals have different corrosion mechanisms. The Flap-11Px provides flexible lining options:
PTFE (F4) Lining
Suitable for:
- Hydrochloric acid;
- Sulfuric acid;
- Sodium hydroxide;
- Ammonia solution;
- Various acidic and alkaline liquids.
FEP (F46) Lining
Suitable for:
- Liquid chlorine;
- Bromine water;
- Highly permeable corrosive chemicals.
This material flexibility allows the level indicator to meet a wider range of chemical process requirements.
3. Stable and Reliable Level Measurement
The magnetic level indicator operates based on the principle of communicating vessels and magnetic coupling.
The internal magnetic float moves with the liquid level, driving the external magnetic flap display synchronously.
The measurement principle provides several advantages:
- Real-time level indication;
- No external power required for local display;
- Clear visual reading;
- Stable operation;
- Not affected by liquid conductivity or dielectric constant.
It is especially suitable for large chemical storage tanks requiring continuous level monitoring.
4. Remote Transmission and Alarm Functions
To meet modern automation requirements, the project was equipped with:
- 4–20 mA remote transmitters;
- Magnetic level switches for alarm functions.
The liquid level signal is transmitted directly to the DCS system.
When the liquid level reaches preset high or low limits, the system can trigger alarms or automatically control pumps, improving process safety and automation efficiency.
The supporting transmitters and switches are available with explosion-proof options for hazardous areas.
5. High Environmental Protection Rating
Chemical plants often operate under harsh environmental conditions, including:
- Acid mist;
- High humidity;
- Outdoor installation;
- Chemical splash exposure.
The Flap-11Px supports high protection ratings up to IP67, ensuring reliable operation in demanding industrial environments.
Installation and Commissioning
To ensure long-term reliable operation, the following installation procedures were implemented:
- Isolation valves were installed at the upper and lower process connections for maintenance convenience;
- The level indicator was installed vertically;
- Magnetic materials were kept away from the measuring chamber to avoid interference;
- The display panel was calibrated after installation;
- During startup, the upper valve was opened first, followed by the lower valve, allowing the medium to enter smoothly;
- Remote transmitters and switches were properly grounded.
Application Results
After one year of operation, the customer evaluated the performance of the equipment.
Stable Level Display
The liquid level indication remained accurate and stable without:
- Display fluctuation;
- Magnetic flap sticking;
- Measurement interruption.
No Corrosion Leakage
The flange connections and lined chamber remained in good condition, with no signs of:
- Chemical leakage;
- Lining damage;
- Corrosion failure.
Reduced Maintenance Costs
Compared with previous conventional magnetic level indicators, maintenance frequency was significantly reduced, lowering spare parts consumption and labor costs.
Improved Process Automation
The stable 4–20 mA signal was successfully integrated into the DCS system, enabling:
- Remote monitoring;
- Automatic alarm;
- Better production management.
Why Choose Lined Magnetic Level Indicators for Corrosive Storage Tanks?
For acid and alkali storage tanks, the level measurement device must provide not only corrosion resistance but also safety, reliability, and easy maintenance.
Compared with other technologies:
Glass Tube Level Gauges
Potential issues:
- Fragile glass components;
- Safety risks under chemical conditions.
Differential Pressure Level Transmitters
Potential issues:
- Impulse line blockage;
- Maintenance difficulties.
Radar Level Sensors
Potential issues:
- Installation requirements;
- Possible interference under certain process conditions.
The lined magnetic level indicator offers unique advantages:
- Excellent resistance to strong acids and alkalis;
- Direct visual level indication;
- No power required for local display;
- Optional remote transmission;
- Simple structure and reliable operation;
- Low maintenance requirements;
- Long service life in harsh environments.
Typical Applications
The Flap-11Px lined magnetic level indicator is widely used in:
- Chlor-alkali chemical plants;
- Petrochemical facilities;
- Fine chemical production;
- Lithium battery material plants;
- Environmental protection systems;
- Pharmaceutical industries;
- Power plant chemical treatment systems;
- Acid and alkali storage facilities.
Typical applications include:
- Brine tanks;
- Alkali circulation tanks;
- Dechlorination towers;
- High-purity hydrochloric acid storage tanks;
- Liquid chlorine tanks;
- Bromine water tanks;
- Ammonia solution tanks;
- PVC production process vessels.
Conclusion
In highly corrosive acid and alkali storage applications, the reliability of liquid level measurement equipment directly affects production safety and operational efficiency.
Compared with conventional stainless-steel level indicators, the Jiwei Flap-11Px Lined Magnetic Level Indicator provides a more reliable solution through:
- PTFE/FEP corrosion-resistant lining technology;
- Optimized anti-leakage structural design;
- Stable magnetic coupling measurement principle;
- Remote monitoring and alarm capabilities;
- High environmental protection performance.
By providing customized corrosion-resistant solutions for different chemical media, Jiwei Automation helps chemical enterprises improve operational safety, reduce maintenance costs, and achieve more efficient tank level management.
The Flap-11Px is an ideal choice for continuous, safe, and accurate liquid level measurement in harsh corrosive environments.
