How to Read Radar Level Meter Hazardous-Area Markings

The letters Ex do not prove that a radar level meter is suitable for a particular hazardous location. The complete marking describes the protection concept, gas or dust group, temperature limit, equipment protection level and sometimes ambient restrictions. Engineers must match the exact certificate and installation conditions to the site's classification.

Start from the site classification

Obtain the approved zone or division, gas or dust classification, temperature requirement and ambient range for the actual mounting point. Do not infer classification from the process name. The vessel interior, roof and wiring route may have different conditions.

Confirm whether gas, vapor, combustible dust or a hybrid hazard is credible. A gas approval does not automatically cover dust, and an enclosure suitable for dust may use different installation conditions from an intrinsically safe gas circuit.

Read the complete marking

Identify the protection concept, equipment group, gas or dust subgroup, temperature class or maximum surface temperature and equipment protection level. Check suffixes and certificate numbers. Each element must be equal to or more suitable than the site requirement under the governing scheme.

Use the certificate, not a marketing summary, to confirm special conditions of use. An X suffix may indicate restrictions such as impact protection, electrostatic precautions, approved cable entries or temperature-dependent ratings.

Verify the electrical loop

For intrinsically safe circuits, compare entity parameters for the transmitter, barrier, cable capacitance and inductance. Confirm grounding and segregation. A device label alone does not validate the complete loop, and substituting a barrier or cable can change compliance.

For other protection concepts, check glands, conduit seals, unused entries, cover engagement and permitted wiring method. Use components certified for the relevant protection and environmental conditions.

Include process and temperature effects

Process temperature can raise surface temperature or reduce the permitted ambient range. Review the certificate tables for the exact assembly and seal. Thermal extensions or insulation must be installed according to the approved conditions.

Chemical compatibility, pressure rating and measurement performance remain separate checks. Hazardous-area approval does not prove that the antenna or gasket suits the medium or that the beam path is acceptable.

Control installation and maintenance

Record label photographs, certificate revision, model code, barrier and cable details. Inspect bonding, glands, enclosure seals and electrostatic precautions before energizing. Protect nonmetallic antenna surfaces from charging or impact where required by the instructions.

Maintenance must preserve the protection concept. Do not open energized enclosures or replace fasteners, seals or entries outside the approved procedure. After repair, document parts and required tests before return to service.

Worked marking review

A radar is offered for a dusty grain silo because its brochure says explosion proof. The site requires a specific dust zone, group and maximum surface temperature. Certificate review shows the proposed option covers gas only, so it is rejected before purchase and replaced with the correctly certified dust version.

The approved record includes the full model code, marking, certificate, ambient and process limits, gland and grounding requirements. Receiving inspection can then detect an incorrect variant before installation.

Questions for the supplier

Request the certificate and schedule for the exact order code, not a similar product photograph. Ask the supplier to identify special conditions, permitted ambient and process temperatures, compatible glands or barriers and any restrictions on nonmetallic surfaces.

If the marking differs between the quotation, nameplate and certificate, stop approval until the discrepancy is resolved. Commercial equivalence is not enough when a suffix changes the approved protection concept or hazardous-area boundary.

Engineering checklist

• Obtain the approved site classification.
• Match gas or dust group and temperature requirement.
• Read the complete marking and certificate conditions.
• Validate barrier, cable and gland arrangements.
• Check process and ambient temperature tables.
• Preserve label photographs and exact model code.

Frequently asked questions

Is an Ex-marked radar suitable for any hazardous area?

No. Every part of the marking and certificate conditions must match the site classification.

Does gas certification cover combustible dust?

Not automatically. Dust protection uses its own marking, group, temperature and installation conditions.

Can a certified transmitter use any cable gland?

No. The gland and wiring method must preserve the approved protection concept and environmental rating.

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