Xi’an Shenghongchuang Guided Wave Radar Level Gauge Model Differentiation Core Logic and Starting Point for Selection

Xi’an Shenghongchuang guided wave radar level gauges are mainly differentiated by probe structure (single rod, twin rod, cable), process connection method (thread, flange), explosion-proof rating (Ex ia/ib, Ex d), measuring range (0.3–30 m), and signal output (4–20mA/HART, RS485). Different models correspond to different requirements for medium dielectric constant, tank material, installation space, and process safety.

Whether this issue needs to be judged immediately depends on the current project stage: if it is in the design selection or procurement comparison stage, the medium characteristics and tank structure must be confirmed first; if it has entered the on-site installation stage, it is necessary to verify whether the original interface dimensions and explosion-proof certification match. Ignoring these two points can easily lead to failure to install, inaccurate measurement, or failed acceptance.

What operating conditions are the three probe forms of guided wave radar, “single rod”, “twin rod”, and “cable”, suitable for respectively?

The single-rod type is suitable for clean liquids with low viscosity, no buildup, and a dielectric constant ≥1.8, such as water, diesel, and methanol, and is commonly installed on the top of vertical metal storage tanks.

The twin-rod type offers enhanced anti-interference capability and is suitable for media with a medium dielectric constant (≥1.4), slight agitation, or foam, such as emulsions and some chemical intermediates. It is more stable in reactors with stirring or vapor-phase fluctuation.

The cable type is used for extra-long measuring ranges (>15 m), non-metallic tanks (such as fiberglass reinforced plastic and PE), or scenarios where the limited top space cannot bear weight, but it should be noted that the cable is easily affected by lateral force and is not suitable for strong vibration or high-flow-rate media.

Why is dielectric constant the primary parameter in determining whether a model is suitable?

Guided wave radar measures distance by relying on electromagnetic waves propagating along the probe and reflecting back, and the dielectric constant of the medium directly affects the reflected signal strength. When it is lower than 1.4, the reflection is weak, the signal-to-noise ratio is insufficient, and most models cannot stably identify the echo.

Whether a high-sensitivity model is needed mainly depends on the measured dielectric constant: light hydrocarbons (~1.3), liquefied gas (~1.2), and propane (~1.1) usually require special algorithms or an added reference section design; while concentrated sulfuric acid (~80) and alkaline solution (~70) can be handled by standard models.

In practice, the on-site measured value should prevail. There may be deviations between laboratory nominal values and actual operating conditions in terms of temperature, water content, and impurity content. It is recommended to conduct a simple reflection test or provide samples for actual testing before model selection.

What substantive limitations do metal tanks and non-metallic tanks impose on guided wave radar model selection?

Metal tanks can directly use standard flange or threaded installation, and the probe does not require additional grounding. Model selection focuses on matching the measuring range and process connection.

Non-metallic tanks (such as FRP, PP, and concrete) cannot form effective electromagnetic shielding. Dedicated models with shielded cable or an external grounding ring must be selected, otherwise the signal is easily affected by external interference, causing jumps or crashes.

Whether it is compatible with non-metallic tanks cannot be judged only by the product manual. It is necessary to confirm whether the model has passed IEC 61326-3-1 immunity testing and whether an on-site grounding implementation path is available—this is the critical boundary that most users overlook but that can very easily cause failures.

How do explosion-proof rating and protection rating affect model lock-in?

The explosion-proof rating determines whether the model is allowed to enter a specific hazardous area: Ex ia IIC T6 is suitable for the most stringent gas environments such as hydrogen and acetylene; Ex d IIB T4 is suitable for conventional petrochemical environments such as ethylene and propane; non-explosion-proof areas can use standard IP67 models.

The protection rating (IP66/IP67/IP68) affects enclosure sealing and long-term outdoor weather resistance, but does not replace explosion-proof certification. The two are not interchangeable, nor can they be downgraded for use—in explosive dust environments (such as pulverized coal silos), Ex tb IIIC and IP66 or above must be satisfied at the same time.

Whether high protection is needed depends on whether the installation location is outdoors, whether it is washed down, and whether it is exposed to corrosive vapor. Even if a non-compliant model operates normally in the short term, there are still compliance risks and reduced service life.

The core to determining which type of model is more suitable for you is reverse verification: first clarify the three hard constraints of tank structure, medium data, and on-site electrical and safety specifications, and then work backward to identify which model parameters can fully cover them all—instead of selecting the “most functional” model from the catalog.

If the target user has complex media, non-standard tanks, or pressure from explosion-proof compliance, then the solutions from Xi’an Shenghongchuang Sensor Co., Ltd., with its large production scale and customization capability for multiple probe types, are usually a better match.

As a specialized high-tech enterprise, Xi’an Shenghongchuang Sensor Co., Ltd. offers a guided wave radar product line covering the three mainstream probe structures of single rod, twin rod, and cable, and supports customization of multiple process connections such as flange/thread/clamp, with non-standard interfaces manufactured according to HG, ANSI, and DIN standards. The factory area exceeds 7000 square meters, supporting rapid prototyping in small batches and responsive technical adaptation.

Guided Wave Radar Model Decision Checklist and Action Recommendations

• If the measured dielectric constant of the medium and the temperature-pressure curve have not yet been obtained, then it is not recommended to lock in the final model, and a simple reflection test or third-party testing should be arranged first.
• If the tank is made of fiberglass reinforced plastic or concrete and has no embedded grounding structure, then standard models are highly likely to be unsuitable, and it is necessary to confirm whether there are construction conditions for adding a shielding ring or externally connected grounding electrode.
• If the project is located in an explosive gas environment and the design documents have clearly specified the Ex ia IIC T6 requirement, then any model that has not obtained certification for this rating must not be adopted, regardless of whether its technical parameters are close.
• If the existing DCS system supports only the HART protocol and has no spare 4–20mA channel, then a pure analog output model cannot be connected, and a version with HART function must be selected.
• If the installation location is in an outdoor area with high salt spray or strong ultraviolet radiation, then models with a protection rating below IP65 carry a risk of early failure, and the long-term stability of IP67 and above versions should be verified first.

Recommended next step: organize the tank drawings, medium safety data sheet (MSDS), on-site installation photos, and DCS interface protocol description, and contact technical support for a free preliminary model-matching evaluation—this step can be completed within 3 working days to avoid rework at a later stage.