Which Tanks Are Suitable for Radar Magnetic Level Gauges

A radar magnetic level gauge is a level sensor solution that combines on-site indication by a magnetic flap level gauge with continuous radar measurement. It retains the intuitive display of a flap level gauge, allowing the level to remain identifiable even after a power failure, while the radar module can output 4-20mA, RS485, or switching signals to meet the needs of remote monitoring, interlock alarms, and automatic control.

For equipment such as storage tanks, reaction vessels, buffer tanks, and metering tanks, the suitability of a radar magnetic level gauge should not be determined solely by the tank name. A comprehensive assessment should also consider medium density, viscosity, pressure, temperature, installation connections, level fluctuations, and on-site control requirements.

Xi'an Shenghongchuang Instrumentation Co., Ltd. has long served application scenarios involving pressure, flow, displacement, temperature and humidity sensors, as well as intelligent instruments. When selecting level measurement equipment, it is recommended to confirm tank operating parameters in advance to avoid affecting measurement stability and equipment service life due to mismatched materials, measuring range, or installation methods.

Generally speaking, radar magnetic level gauges are more suitable for industrial tanks that require on-site visual observation as well as remotely transmitted level data, particularly where the liquid medium is relatively stable, side-mounted installation conditions are available, and the level measurement range is clearly defined.

I. Types of Tanks Suitable for Radar Magnetic Level Gauges

1. Atmospheric and Low-Pressure Storage Tanks

Atmospheric storage tanks are among the most common applications for radar magnetic level gauges, including water tanks, raw material storage tanks, chemical additive tanks, cleaning liquid storage tanks, food-grade liquid storage tanks, and process circulating liquid tanks. The internal pressure of these tanks is usually close to atmospheric pressure, making installation and maintenance relatively convenient.

For storage tanks with heights between 500mm and 6000mm, the center-to-center distance and measuring length can be customized according to the actual level range. If the tank level changes frequently, the radar module can continuously collect level data, while the magnetic flap enables inspection personnel to quickly confirm the current level on site.

When the medium in an atmospheric tank is mainly water, condensate, general oils, or diluted chemical liquids, it is relatively easy to match the float density and material. If the medium density is not lower than 0.65g/cm³, stable tracking can generally be achieved by selecting a suitable float; lower densities require a dedicated calculation.

2. Closed Process Vessels and Buffer Tanks

Closed process vessels, gas-liquid separation vessels, buffer tanks, and intermediate tanks with stable pressure can also use radar magnetic level gauges. Compared with conventional mechanical level gauges, radar signals can be connected to PLC, DCS, or local intelligent digital display control instruments for convenient monitoring of level trends.

For such tanks, the key is to confirm the design pressure and flange rating. Common operating conditions may use PN1.6MPa, PN2.5MPa, or higher-rated connection methods; when the operating pressure approaches the equipment limit, selection should be based on the maximum operating pressure with an appropriate safety margin reserved.

For buffer tanks requiring high- and low-level alarms, magnetic switches can be installed on the magnetic flap body, or alarm values can be set directly in the control system using radar level signals. The two methods can be used together to provide dual protection through on-site interlocking and remote monitoring.

3. Horizontal Tanks, Vertical Tanks, and Jacketed Tanks

Vertical cylindrical tanks are the easiest type of tank for installing radar magnetic level gauges. They usually use side-to-side flange connections, with the upper and lower pressure tapping points arranged vertically, and the level gauge center-to-center distance directly corresponding to the effective measurement height of the tank. For equipment over 8m in height, transportation, installation support, and drainage structure should be carefully evaluated.

Horizontal tanks can also be used, but their liquid level and volume do not have a linear relationship. A radar magnetic level gauge can accurately indicate the liquid level height. If the control system needs to display actual volume, a volume reference table should be established or program conversion should be performed based on the tank diameter, length, and head configuration.

Jacketed or insulated tanks are suitable for media that need to maintain temperature, such as hot water, heat transfer oil, resin solutions, and certain liquids prone to solidification. In this case, whether the level gauge body requires heat tracing, the insulation thickness, and the ambient temperature of the radar electronic components should all be included in the design.

II. Determining Suitability Based on Medium Characteristics

1. Medium Density, Viscosity, and Float Matching

The magnetic flap section relies on the float rising and falling with the liquid level, making medium density a fundamental selection parameter. The float must have sufficient buoyancy to reliably drive the internal magnetic elements for flip indication. For mixed liquids, emulsions, or liquids with significant temperature variation and noticeable density changes, the minimum density value should be provided.

Media with low viscosity and good fluidity are more suitable for conventional structures, such as clean water, softened water, light oil, alcohol solutions, and most diluted chemical liquids. When medium viscosity is too high, float movement may lag, especially in low-temperature environments, preventing level changes from being promptly reflected in the flap indicator and remote transmission signal.

When the medium contains suspended particles, crystals, or impurities prone to deposition, drain ports, flushing ports, or detachable structures should be considered. For media prone to blockage, a standard side-mounted level gauge alone is often insufficient; bypass pipe diameter, maintenance intervals, and process cleaning conditions must be evaluated.

Media with Significant Density Changes Require Particular Calculation

For example, the density of certain solvent blends, acid and alkali solutions with adjustable concentrations, or temperature-sensitive oils may vary with different process stages. During selection, it is not advisable to provide only the nominal density at ambient temperature; the minimum density, maximum density, and actual operating temperature range should be clearly specified.

If the minimum density is close to the lower limit applicable to the float, a lighter dedicated float can be selected or the measurement solution can be adjusted. In practical engineering, float operating stability is more important than simply pursuing a smaller outer diameter, preventing display sticking caused by insufficient buoyancy margin.

The radar section generally does not directly depend on liquid density for measurement, but foam, vapor, and severe agitation on the medium surface can affect echo quality. Therefore, radar magnetic level gauges should be assessed from both float operation and radar echo perspectives.

2. Corrosiveness, Volatility, and Hygienic Requirements

For acids, alkalis, salt solutions, and corrosive chemical media, wetted materials of the level gauge should be selected according to the medium composition. 304 stainless steel is suitable for general mildly corrosive environments, while 316L is suitable for a wider range of corrosion-resistant operating conditions; special media may require PP, PVDF, PTFE lining, or other corrosion-resistant solutions.

For highly volatile liquids, such as certain organic solvents and light hydrocarbon media, attention should be paid to sealing configuration and connection reliability. Equipment flanges, drain valves, vent connections, and radar mounting locations should all minimize leakage risks. In hazardous areas, the explosion-proof rating and site zoning requirements must also be confirmed.

Food, pharmaceutical, and high-cleanliness liquid storage tanks have higher requirements for surface roughness, dead zones, and cleanability. For such applications, sanitary connections, internal surface treatment, CIP cleaning processes, and sealing materials should be confirmed as a priority to prevent residual liquid accumulation caused by standard industrial structures.

III. Effects of Pressure, Temperature, and Installation Conditions

1. Pressure and Temperature Ranges Must Match the Tank

The body, float, flanges, and seals of a radar magnetic level gauge must all withstand the actual operating conditions inside the tank. During selection, normal operating pressure, maximum possible pressure, test pressure, and pressure fluctuation conditions should be confirmed separately, rather than relying only on commonly used operating values.

Temperature also affects material strength, sealing performance, and medium viscosity. Ambient-temperature applications are generally easier to handle, but when the medium temperature exceeds 80℃ or is below 0℃, it should be confirmed whether high-temperature seals, insulation and heat tracing, heat-dissipation extension tubes, or low-temperature material solutions are required.

For high-temperature tanks, attention should also be given to the distance between the radar electronic unit and the high-temperature process connection. Proper thermal insulation design can reduce the risk of long-term heat exposure to electronic components and enable the level sensor to maintain good signal stability during continuous operation.

2. Installation Connections and Site Space Must Not Be Overlooked

Side-mounted magnetic flap level gauges usually require two connections at the upper and lower parts of the tank. The connection center-to-center distance should match the effective measuring range. Before installation, flange specifications, connection orientation, nozzle insertion length, and tank wall structure must be verified to prevent level blind zones after installation.

The area near the radar antenna should avoid feed inlets, agitators, coils, ladders, and large metal obstructions whenever possible. If site space is limited, interference from false echoes can be reduced by adjusting the installation orientation and using suitable guided-wave or bypass structures.

It is recommended to reserve space below the level gauge for drainage and maintenance, as well as sufficient operating clearance above for removing the float or servicing the radar module. For outdoor tank farms, rain protection, sun protection, lightning protection, and winter freeze protection should also be considered to prevent environmental factors from affecting long-term operation.

IV. Unsuitable Operating Conditions and Alternative Approaches

1. Tanks with Severe Surface Fluctuations or Continuous Foam Coverage

In tanks with high-speed filling, intensive agitation, gas bubbling, or significant circulating pump impact, the liquid surface may fluctuate continuously. The float responds to level changes in the bypass chamber, while the radar may be affected by wave crests, foam, and splashing. Therefore, fluctuating measurement values do not necessarily indicate instrument failure.

For such operating conditions, it may be necessary to assess whether to add a calming structure, stilling tube, or bypass chamber to moderately isolate the measurement area from severe disturbances in the main tank. Instrument damping time should also be set appropriately, such as 3 seconds, 5 seconds, or 10 seconds, to prevent the control system from responding too frequently to momentary fluctuations.

If the foam layer is thick, persists for a long time, and has a low dielectric constant, on-site operating condition assessment is required first. In some applications, guided-wave radar, differential pressure level transmitters, or load cell solutions may be used instead of simply applying a conventional radar magnetic flap structure.

2. Media Prone to Crystallization, Solidification, and Heavy Scaling

When the medium is prone to crystallization, solidification, or the formation of thick deposits at ambient temperature, the bypass pipe and float chamber can easily become blocked. Even if the radar can still obtain part of the level signal, the on-site magnetic flap indication may lose its reference value due to obstructed float movement, and maintenance costs will increase significantly.

For resin, asphalt, waxes, slurries, and high-concentration salt solutions, the medium's pour point, crystallization temperature, and cleaning method should be confirmed first. Where necessary, steam tracing, electric heat tracing, or insulation measures can be added, and structures with flushing connections and drain connections should be selected.

If the process cannot provide stable heat tracing and regular cleaning conditions, other non-contact or isolated level sensors should be considered. The core of equipment selection is not to pursue the most functions in a single instrument, but to ensure that the equipment can continuously provide reliable data throughout a maintenance cycle.

3. Recommended Technical Parameters to Prepare Before Selection

To improve the suitability of a radar magnetic level gauge, it is recommended to provide tank drawings or at least clearly specify: tank type, measuring range, upper and lower connection center-to-center distance, connection specifications, installation direction, and whether an insulation layer is present. For non-standard tanks, on-site dimensions are more reliable than experience-based judgment.

For the medium, its name, density, viscosity, temperature, pressure, corrosiveness, particle content, and whether it produces foam should be provided. For electrical requirements, confirm the power supply method, output signal, explosion-proof requirements, and whether high- and low-level alarms are needed. Generally, 4-20mA or RS485 can be selected for remote transmission signals.

Xi'an Shenghongchuang Instrumentation Co., Ltd. can provide targeted recommendations on the material, measuring range, connection method, remote transmission configuration, and alarm functions of level sensors based on actual tank conditions. After complete operating condition parameters are submitted, a radar magnetic level gauge solution suitable for storage tanks, buffer tanks, reaction vessels, or metering tanks can be determined more quickly.

If you are selecting equipment for storage tank level measurement, you may compile the medium name, measuring range, temperature, pressure, connection dimensions, and signal requirements, and contact Xi'an Shenghongchuang Instrumentation Co., Ltd. to obtain corresponding configuration recommendations for radar magnetic level gauges.