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Cap Analog 4100

RF Capacitance Level Transmitter

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Cap Analog 4100

The Cap Analog 4100 is designed for process engineers, instrumentation specialists, and plant operators who require accurate, maintenance-free, and intrinsically safe continuous level measurement across liquids, slurries, or bulk solids.

The transmitter uses two-wire RF capacitance technology with loop-powered 4–20 mA output and a compact explosion-proof design for simple installation and long-term reliability.

Unlike traditional transmitters that require frequent recalibration or suffer from coating buildup and dielectric drift, the Cap Analog 4100 incorporates independent zero and span calibration, coating-rejection circuitry, and temperature-stable electronics, ensuring dependable accuracy even in demanding process environments.

With universal probe materials, wide capacitance range selection, and loop-powered simplicity, the Cap Analog 4100 provides high-performance level measurement for chemical, food and beverage, wastewater, and bulk storage applications while maintaining a low total cost of ownership.

Cap Analog 4100
Cap Analog 4100 RF Capacitance Level Transmitter
Cap Analog 4100

Features

Two-Wire Loop Power

A loop-powered 4–20 mA design reduces wiring complexity, lowers installation cost, and simplifies deployment in remote or retrofit applications.

RF Capacitance Sensing

Measures dielectric changes with stable electronics, enabling drift-free, continuous level measurement in liquids, slurries, powders, and granular solids.

Explosion-Proof Housing

A cast aluminum enclosure rated for Class I Div 1 ensures safe operation in hazardous environments containing flammable vapors or combustible dust.

Independent Calibration Pots

Dedicated zero, span, and calibration controls allow precise field adjustment without cross-interaction, ensuring stable long-term performance.

Wide Dynamic Range

Four DIP-switch extensions provide 10–30,000 pF capability, supporting diverse media from low-DK hydrocarbons to highly conductive slurries.

High Temperature Stability

Electronics with ±0.01%/°F thermal stability maintain consistent output accuracy even under significant ambient or process temperature variations.

Applications

  • Chemical Processing Tanks: Provides stable, drift-free level measurement across varied chemical compositions, dielectric ranges, and temperatures commonly found in process vessels.
  • Wastewater & Sludge Basins: Maintains reliable output in conductive slurries, foaming liquids, or mixed-phase environments where ultrasonic or radar devices struggle.
  • Food & Beverage Tanks: Sanitary probe options allow continuous level monitoring in hygienic environments without contamination risk or frequent cleaning requirements.
  • Powder & Granular Silos: Accurately monitors powders, grains, or dry materials where dust affects non-contact sensors, ensuring dependable solids-level control.
  • Hazardous-Area Storage: Explosion-proof housing and 4–20 mA loop power support safe measurement in flammable, remote, or unmanned chemical and petroleum tanks.
  • Bulk Solids Storage: Handles powders, pellets, and granular materials using RF capacitance unaffected by dust clouds, aeration, or solids buildup on probe surfaces.
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Specifications

Measurement Technology

RF Capacitance; integral two-wire transmitter

Output

4–20 mA DC (loop-powered, isolated)

Supply Voltage

24 V DC nominal (12–28 V range)

Load Resistance

600 Ω max @ 24 V DC

Dynamic Range

10 pF–30,000 pF (four selectable ranges via DIP switches)

Zero / Span Adjustment

15-turn independent potentiometers, non-interactive

Temperature Stability

±0.01 % / °F (±0.018 % / °C)

Probe Mounting

¾″ or 1″ NPT; optional flanged process connection

Probe Materials

316 SS, Teflon®, Kynar®, or Halar® insulated rods and cables

Operating Temperature

–40 °F to +160 °F (–40 °C to +71 °C) electronics

Process Pressure

up to 150 psig (10 bar), depending on probe design

Housing

Cast aluminum, explosion-proof and weather-tight (NEMA 4/4X/7/9)

Enclosure Hazardous Area Ratings

Class I Div 1 Groups C & D; Class II Div 1 Groups E, F, G

Calibration Features

Zero, Span, and Cal potentiometers; invert switch; built-in test points (TP1/TP2)

Optional Accessories

DFI-150 digital field indicator, AFI-150 analog indicator, and 920-2A dual set-point power supply

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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 Cap Analog 4100 different from standard capacitance transmitters?

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It uses a two-wire loop-powered design with temperature-stable electronics and coating-rejection circuitry, providing drift-free, low-maintenance measurement.

What is the benefit of the two-wire loop-powered design?

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The primary benefit is reduced wiring cost and complexity. The Cap Analog 4100 draws its power directly from the 4–20 mA signal loop, eliminating the need to run separate power supply cables. This simplifies installation and reduces both the material and labor costs for new and retrofit projects.

Can it be installed in hazardous areas?

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Yes. The 4100 features an explosion-proof aluminum housing certified for Class I Div 1 and Class II Div 1 environments.

How is calibration performed?

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Operators can use independent zero, span, and calibration potentiometers for quick field tuning, with DIP switches for range selection and an invert option for signal direction.

Is it compatible with PLC or SCADA systems?

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Absolutely. The standard 4–20 mA output integrates easily with process control and monitoring systems.

What probe types are available?

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Probes are offered in 316 SS, Teflon®, Kynar®, and Halar®, available as rigid rods or flexible cables to suit liquids, slurries, and solids.

How does it handle coating or buildup?

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The built-in coating-rejection circuit filters out noise from viscous or sticky materials, maintaining consistent accuracy.

How does the coating-rejection circuitry work?

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The transmitter is designed with a specific probe and circuitry that measures the change in capacitance when the product level changes. The circuitry is able to electronically ignore the capacitance caused by a thin layer of conductive buildup on the probe (1,000 µmho), ensuring the measurement remains stable and accurate despite sticky media.

Can this transmitter measure bulk solids?

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Yes. The Cap Analog 4100 is versatile enough to be used for level monitoring of bulk solids and granular materials. Unlike other technologies, the RF capacitance principle provides a continuous measurement that is generally not affected by dust or bridging of the material.

Summary

With decades of proven performance in process and storage applications, Cognesense through its Cognesense brand offers robust RF capacitance technology built for modern plants. 

The Cap Analog 4100 combines two-wire simplicity, high stability, and industrial durability, making it a premier choice for continuous level measurement in liquids, slurries, and solids. 

Whether used in chemical processing, wastewater treatment, or tank-farm automation, it delivers dependable analog accuracy and low total cost of ownership.

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