Drexelbrook Intellipoint Series RF Admittance Level Switch

Overview

The Drexelbrook Intellipoint Series RF Admittance Level Switch is an engineered solution for reliable point-level detection in demanding industrial process environments. Based on the principle of radio-frequency (RF) admittance measurement, the device detects changes in the composite impedance—comprising capacitance and conductance—at the sensor probe interface when material contacts or departs from the sensing element. Unlike traditional capacitance-based switches, RF admittance technology applies a high-frequency signal (typically in the 1–10 MHz range) to suppress effects caused by coating buildup, moisture, humidity, and variations in dielectric constant or conductivity across diverse media—including slurries, viscous liquids, powders, and granular solids. This makes the Intellipoint series especially suited for applications where false tripping due to bridging, condensation, or adhesion is common. Designed for continuous operation in safety-critical loops, the switch complies with IEC 61508 and is certified to SIL2 per IEC 61511, enabling integration into Safety Instrumented Systems (SIS) for overfill prevention, dry-run protection, and interlock logic.

Key Features

• Intelligent self-calibrating architecture eliminates manual field calibration—no potentiometers or external tuning required.
• Adaptive signal processing compensates in real time for gradual coating accumulation, maintaining stable setpoints without operator intervention.
• Wide operating temperature range: standard models support –40 °C to +200 °C; high-temperature variants rated up to 815 °C with specialized ceramic or Inconel probe construction.
• High-pressure capability: process connections rated to 27.5 MPa (4,000 psi) using ASME B16.5 Class 2500 or equivalent flanged or threaded configurations.
• Flexible power architecture supports both conventional AC/DC supply (24 VDC, 115/230 VAC) and intrinsic safety-compatible loop-powered operation (4–20 mA with HART).
• Integrated diagnostics include continuous probe integrity monitoring, signal-to-noise ratio tracking, and fault logging compliant with NAMUR NE 44 guidelines.
• Multiple explosion protection options available: ATEX II 1/2G Ex ia IIC T6 Ga, IECEx ia IIC T6 Ga, and CSA Class I, Div 1, Groups A–D, T6.

Sample Compatibility & Compliance

The Intellipoint switch reliably detects level in conductive and non-conductive media—including corrosive chemicals, heavy fuel oils, cement powder, fly ash, and polymer melts—without requiring medium-specific recalibration. Its RF admittance algorithm inherently rejects false signals from vessel wall proximity, agitation-induced splashing, or foam formation. The device meets electromagnetic compatibility requirements per EN 61326-1 (industrial environment), functional safety compliance per IEC 61508 Ed. 2 (SIL2), and pressure equipment directive (PED 2014/68/EU) for applicable variants. All units undergo factory verification against traceable standards and ship with full test reports including proof test intervals and PFD_avg calculation documentation.

Software & Data Management

Configuration and diagnostic data are accessible via local push-button interface or remotely using Drexelbrook’s proprietary Intellitool™ configuration software (Windows-based, USB or RS-485 connection). The software supports full parameter backup/restore, event log export (CSV), and firmware updates. For integration into asset management systems, the device provides HART 7 protocol support with standardized device variables (e.g., measured admittance, coating factor, diagnostic status) mapped to FDI EDDs. Audit trails and change logs comply with FDA 21 CFR Part 11 requirements when used with validated host systems under GLP/GMP frameworks.

Applications

• High-temperature boiler drum level interlocks in power generation
• Overfill protection in API 650 storage tanks handling hydrocarbons or solvents
• Low-level detection in silos conveying abrasive mineral powders
• Dry-run prevention for centrifugal pumps in wastewater treatment plants
• Safety-critical level monitoring in pharmaceutical reactor vessels subject to USP and validation protocols
• Interface detection between immiscible liquid phases in chemical separation columns

FAQ

Does the Intellipoint require periodic recalibration during service life?
No—its adaptive learning algorithm continuously adjusts baseline impedance values and maintains detection stability without scheduled recalibration.
Can it be installed in a pressurized stainless-steel reactor operating at 15 MPa and 450 °C?
Yes—select the high-pressure/high-temperature variant with Inconel 600 probe and ASME Section VIII Div. 1 certified flange mounting.
Is SIL2 certification valid for both hardware and software elements?
Yes—the certification covers the complete device architecture, including microcontroller firmware, analog signal conditioning, and voting logic within the safety loop.
How does the switch handle heavy coating on the probe in sticky polymer applications?
It employs dynamic coating compensation: the system distinguishes between true level contact and gradual dielectric drift by analyzing phase-angle shifts and harmonic content of the RF signal.
What documentation is provided for regulatory audits?
Each unit ships with a Certificate of Conformance, SIL2 certification report (TÜV Rheinland or exida), calibration certificate traceable to NIST, and full failure modes and effects analysis (FMEA) documentation.