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Captrol 520

RF Capacitance Liquid & Bulk Solids Level Switch

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Captrol 520

The Captrol 520 is designed for refinery and chemical plant operators, wastewater and industrial process engineers, and OEM equipment designers who require reliable point-level detection in challenging tanks, silos, pits, and bulk storage applications.

The instrument delivers proven RF capacitance switching, universal power compatibility, and rugged probe configurations up to 250 ft in length.

Unlike mechanical floats, optical sensors, or vibrating forks that can foul, drift, or fail in viscous, abrasive, or sticky media, the Captrol 520 uses high-frequency RF technology, coating-rejection circuitry, and independent calibration controls. These features ensure accurate and repeatable switching even in low-dielectric liquids, powders, sludge, and slurries.

With fail-safe protection, adjustable time delay, and explosion-proof construction, the Captrol 520 is an effective solution for overflow protection, pump control, dry-run protection, and safety shutdown systems across oil and gas, chemical processing, water treatment, food production, and general industrial applications.

Captrol 520
Captrol 520 RF Capacitance Liquid & Bulk Solids Level Switch
Cap Point  520

Features

High-frequency RF Sensing

Uses a 2 MHz excitation signal to detect level changes accurately through coatings, low dielectric materials, and electrical noise found in difficult processes.

Coating-rejection Circuitry

Compensates for conductive or sticky buildup on the probe, preventing nuisance trips and ensuring stable switching in viscous or adhesive materials.

Universal Power Compatibility

Accepts 115/230 VAC or 24 VDC, enabling simple retrofits and reducing spare-part requirements across facilities with mixed power standards.

Selectable Fail-safe Logic

Allows high-level or low-level fail-safe modes, ensuring predictable relay behavior during power loss or wiring faults to protect pumps and tanks.

Extended-length Probe Support

Allows rigid or flexible probes up to 250 ft, enabling reliable level detection in deep vessels, tall silos, and remote sumps without custom assemblies.

Hazard-area Certified Enclosure

Explosion-proof NEMA 4/5/7/9/12 housing supports safe installation in Class I & II environments with flammable vapors, dusts, or industrial contaminants.

Applications

  • Sticky Coatings: Coating-rejection RF circuitry prevents false trips when viscous, adhesive, or fouling products cling to probe surfaces during normal operation.
  • Tall Silos: Long rigid or flexible probes up to 250 ft enable accurate detection in deep storage vessels without signal loss or special mechanical supports.
  • Corrosive Liquids: Teflon, Kynar, and Hastelloy probe options maintain performance and service life when exposed to aggressive chemical media or corrosive vapors.
  • Pump Control: Dual-point switching supports pump ON/OFF logic with differential, preventing short-cycling, overflow, or run-dry conditions in sumps or lift stations.
  • Hazardous Areas: Explosion-proof housing and Class I/II approvals allow installation in flammable or dust-laden environments requiring certified protection.
  • Abrasive Solids: Heavy-duty probes withstand wear from granular or fast-moving bulk solids, maintaining stability in bins, hoppers, and material handling systems.
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Specifications

Electrical

Power

115 VAC (95–135 V), 230 VAC (180–270 V), or 24 VDC (18–28 V)

Output

Up to 2 DPDT relays (independent)

Load Rating

5 A @ 115 VAC non-inductive 2.5 A @ 230 VAC non-inductive 3 A @ 26 VDC non-inductive Performance

RF frequency

~ 2 MHz

Sensitivity

Adjustable, suitable for liquids ≥ 1.5 dielectric constant & bulk solids ≥ 10 lb/ft³

Stability

0.01 % / °F

Time Delay

Fixed fast response + adjustable 50 ms–10 s

Electronics Temperature Limits

–40 °F to +160 °F (–40 °C to +71 °C)

Probe Rating (Depends on Type)

up to 450 °F and 400–500 psi

Enclosure Certifications

NEMA 4, 5, 7, 9, 12

Enclosure Hazardous Certifications

NEC Class I C&D, Class II E/F/G

Probe Mounting

¾″ NPT or flange

Probe Types

Rigid, flexible cable, heavy-duty, Teflon, Kynar, Hastelloy

Probe Length

Up to 250 ft

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Contact Support

If you have questions not covered here, please contact the Cognesense support team for assistance.

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What makes the Captrol 520 suitable for challenging media such as sludge or powders?

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Its 2 MHz RF sensing and coating-rejection circuitry ensure accurate switching even with buildup, foam, or low-dielectric materials.

Can the switch be used for both liquids and bulk solids?

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Yes. The RF capacitance technology in the Captrol 520 is highly versatile. It’s sensitive enough to detect level changes in liquids (dielectric constant above 1.5) and is also effective for many bulk solids and powders (bulk density >10 lb/ft3).

Is the Captrol 520 approved for hazardous locations?

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Yes — the housing is explosion-proof and approved for Class I & II hazardous areas.

What power supply options are available?

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It accepts 115 VAC, 230 VAC, or 24 VDC, making it easy to standardize across facilities.

Can the device be used for pump control?

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Yes — dual-point logic and adjustable time delay allow reliable pump-on/pump-off control to prevent short-cycling and overflow.

What is the benefit of the dual DPDT relay outputs?

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The dual DPDT relays provide two completely independent switching circuits. This allows one Captrol 520 unit to handle two separate critical functions simultaneously, such as a high-level overflow alarm and a low-level pump shutoff, reducing the number of devices and tank penetrations required.

What probe lengths are available?

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Probes are available up to 250 ft, ideal for tall silos and deep pits.

Does the Captrol 520 operate correctly in plastic or fiberglass tanks?

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Yes — ground reference and probe options allow accurate sensing in non-metallic vessels.

Summary

The  Cap Point  520 is a rugged, reliable RF-capacitance point-level switch engineered for demanding industrial tanks, sumps, bins, and silos. It delivers dependable operation in viscous, abrasive, corrosive, and dusty environments where other technologies struggle. With universal power, selectable fail-safe logic, flexible probe configurations, and explosion-proof design, the  Cap Point  520 is a cost-effective, field-proven solution for overflow protection, pump control, material handling, and process safety applications across chemical, oil & gas, water/wastewater, food, and general industry.

Cognesense, through its Cognesense brand, brings advanced process reliability backed by decades of RF-level sensing expertise — reducing downtime, preventing overflows, and improving operational confidence.

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