An RF admittance level switch consists of an insulated rod or flexible rope probe with a sealed electronics module, and selection should be driven by media type, build-up compensation features, hazardous-area approval such as ATEX, and mounting options such as horizontal, vertical, flange, side-mount, or flush-mount [S1][S3][S5].
The current directindustry category tracks 18 admittance-RF models from multiple vendors, with AMETEK Drexelbrook shipping the Safety IntelliPoint RF, ThePoint and Multipoint II families, and LSY Trumen offering the model LSY for bulk solids and powders [S1][S2][S4][S5]. Specify what the process will actually do to the probe, not the catalogue number, when writing the requisition.
How an RF admittance switch actually works (and why that matters for build-up)
An admittance point level switch measures both the resistive and capacitive components between a sensing electrode and a reference, so conductive coatings, sticky slurries and damp powders that would fool a plain capacitive probe still register as a real material change at the setpoint [S5].
The practical consequence is that RF admittance is the only capacitive-family technology specified to ignore the residue left on the probe between cycles, which is why directindustry lists 18 admittance-RF models for liquids, solids, slurries, sanitary and hazardous-location duty side by side [S3]. For a primer on the broader capacitive family and where admittance sits inside it, the level switch encyclopedia entry gives the framing used in this guide.
Gate 1 — Media, dielectric and coating tolerance
If the service is conductive water-based slurry, sewage, or wet cement, a standard bare-electrode RF probe will short to the tank wall; the spec line must read "coating-tolerant / guarded electrode" and the vendor data sheet must show a documented coating-immune test [S5].
AMETEK Drexelbrook's Safety IntelliPoint RF is positioned for liquids, slurries and solids where heavy coating is the norm, including sediment-level detection in chemical tanks and sanitary food-industry lines [S1]. The LSY Trumen model targets bulk solids and powders, a lower-dielectric service where guard sensitivity rather than conductive shorting is the failure mode to design against [S5]. The general RF admittance level switch reference lists the typical electrode options — rod, cable and guarded flat plate — that map to these services.
Gate 2 — Mount, vessel and process connection
Directindustry shows the same 18 admittance-RF models split across threaded, flanged, side-mount, top-mount, vertical and flush-mount process connections, with protection tubes available for abrasive and high-temperature services [S3]. Pick the mount to match vessel geometry first; an RF probe is too long to retrofit inside a nozzle sized for a smaller technology.
Flanged mounts (3 listed) suit chemical tanks, side-mounts (3) suit pump-control and overflow service, and flush-mounts (2) suit sanitary and food-industry vessels where cleaning-in-place rules out protruding hardware [S3]. The multipoint II line from AMETEK Drexelbrook is catalogued specifically for pump-control duty on tanks, which is a different process connection story from a silo high-level switch [S4]. For broader mechanical options the industrial switch encyclopedia entry covers vertical, horizontal and insertion styles.
Gate 3 — Hazardous area, sanitary and certification envelope
Seven of the 18 listed admittance-RF models carry hazardous-location approvals and six are certified sanitary for food and pharmaceutical service; buyers in those segments must treat the certification list as a hard gate, not a checkbox [S3].
AMETEK Drexelbrook's ThePoint explicitly markets hazardous-area approvals as a feature and pitches itself as "a good choice for most of your point level application requirements" including the temperature, pressure and material envelopes covered by its sensing-element offering [S2]. AMETEK's Safety IntelliPoint RF covers the same hazardous locations plus sanitary and food-industry service [S1]. If the spec is intrinsically safe or explosion-proof, confirm the exact IEC 60079 / ATEX category with the OEM data sheet; the isolating switch encyclopedia entry explains how galvanic isolation between probe and electronics is implemented on these lines.
Gate 4 — Electronics, output and integration
RF admittance switches are point devices, not continuous transmitters, so the integration question is relay contact rating, DPDT vs SPDT, and whether the housing carries a 4-20 mA loop-power or line-voltage option — not a HART or Foundation Fieldbus stack [S1][S2].
Specify fail-safe direction (high-level or low-level), time delay, and proof-test interval on the requisition. AMETEK Drexelbrook's ThePoint and IntelliPoint share a common sensing-element platform and electronics, which simplifies spare-parts holding across a plant that mixes pump-control, overflow and high-high service on the same vessel [S2][S4]. For sites standardising on infrared or photo-electric point devices, the [infrared level switch encyclopedia entry](/encyclopedia/infrared-level-switch.html) is the contrast technology; the two are complementary, not substitutes, in a typical tank-farm I/O list.
Gate 5 — Options comparison: which line to specify
Three of the five most-quoted 2026 product lines compare cleanly on four decision axes: media, mount, certification and electronics. The table below is built from the AMETEK and LSY data sheets published within the past six months [S1][S2][S4][S5].
AMETEK Safety IntelliPoint RF — liquids, slurries, solids, sanitary, hazardous locations; flange/side/top mount; hazardous-area approvals; shared Drexelbrook electronics platform [S1]. AMETEK ThePoint — liquids, tanks, chemicals; hazardous-area approvals; the broadest temperature, pressure and material envelope in the Drexelbrook line [S2]. AMETEK Multipoint II — liquids, tanks, pump control; optimised for pump-chamber setpoints and overflow; same sensing-element family as IntelliPoint and ThePoint [S4]. LSY Trumen model LSY — bulk solids, powders; lower-cost entry targeted at Indian and export OEM channels; hazardous and sanitary variants confirm per order [S5].
Who RF admittance is FOR, and who should look at alternatives
RF admittance is FOR: conductive slurries with heavy coating, sticky powders, hygienic food/pharma service, pump-chamber control, and overflow / run-dry protection on tanks and silos where the probe can be coated in process residue [S1][S2][S4][S5].
RF admittance is NOT for: clean, low-dielectric hydrocarbons, non-contact level measurement on large storage tanks, or any service where a guided-wave radar, 26 GHz FMCW radar or non-contact optical switch will do the job with no probe intrusion. For a process control engineer weighing this against a continuous level device, the broader automatic level encyclopedia entry gives the trade-off framework, and a 2026 radar selection comparison covers the 26 GHz, 6.8 GHz, 120 GHz and guided-wave alternatives. For unrelated flow-service selections, the 2026 [turbine vs ultrasonic flowmeter comparison](/news/turbine-vs-ultrasonic-flowmeter-selection-specs-for-process-and-custody-service.html) and the [orifice plate selection field guide](/news/orifice-plate-flowmeter-selection-criteria-2026-engineering-field-guide.html) sit on the same site.
Failure modes and field watch-outs
The most common admittance-switch failure in coated service is the electronics module losing calibration when the guard electrode is bridged by a continuous wet film; the second is mechanical fatigue of a long cable-suspended probe in an agitated vessel [S3][S5].
Insist on a documented coating-immune test, a high-temperature rating that matches the CIP cycle on sanitary lines, and a vendor-supplied calibration certificate keyed to the serial number. AMETEK Drexelbrook's three 2026 product sheets explicitly bundle hazardous-area approvals, sanitary ratings and pump-control duty into a single platform, which is the right way to control spares across a plant [S1][S2][S4]. Maintenance-free and protection-level ratings are listed on 10 and 14 of the 18 models respectively, which is a usable proxy for service-interval planning [S3].
Standards, sourcing and quoting checklist
Specifying engineer should pin the requirement to IEC 60079 series for hazardous locations, ATEX 2014/34/EU for EU explosive atmospheres, and 3-A / EHEDG for sanitary and food-industry service, then confirm the certificate number on the vendor data sheet [S1][S2][S3].
The 2026 supplier map shows AMETEK Drexelbrook (Safety IntelliPoint RF, ThePoint, Multipoint II) as the dominant Western OEM and LSY Trumen as a parallel Indian supplier for bulk-solids and powder service; multiple Chinese vendors continue to offer admittance-RF probes and meters at sub-USD-300 price points for non-hazardous OEM channels [S1][S2][S4][S5][S6]. Watch for: the next Drexelbrook electronics-platform firmware revision in 2026, and any move by the Indian and Chinese suppliers to publish IECEx certificates in place of the current domestic-only approvals [S3][S5][S6].