EchoBeam 80-GHz radar level sensors received CSA, ATEX and IECEx intrinsically safe approval in April 2026 for liquid and solids service in hazardous areas [S1], which makes 80-GHz FMCW non-contact radar the credible default for sump duty in zone-classified plant.
A sump duty point is the worst radar application: short measuring span, turbulent surface, foam, condensate, and typically a low dielectric hydrocarbon or aqueous chemical. 80-GHz radar narrows the beam to roughly 3-4 degrees, which suppresses the sidewall reflections that blind 26-GHz sets in a 1-2 m sump. The right RFQ line is what separates a clean quote from a two-week clarifications loop, and the line items below are written in the order a process engineer actually fills the datasheet.
Process-side data the vendor cannot guess
Process medium, full operating temperature range, full pressure range, full measuring span (not nominal), and the lowest expected dielectric constant must be on the first line of every RFQ [S3]. For a hazardous sump the medium line is the single most requote-triggering field: a vendor that has to assume water will assume a cheaper horn than a vendor that has to assume a hydrocarbon condensate below dielectric 2.0 [S1].
State the dielectric range you have actually measured, not the textbook value. Hydrocarbon condensates and light oils sit near 1.6-2.5; aqueous caustics and acids sit near 50-80. 80-GHz radar with a 1-inch process connection still loses lock below dielectric 1.4 unless the vendor confirms a still-well or coaxial probe configuration, so write the dielectric line as a range, e.g. "1.8 to 12 typical, 1.4 minimum at start-up" [S1]. Temperature and pressure go in pairs because the gasket and O-ring choice rides on both. An EPDM O-ring rated 60 deg C collapses a 150 deg C acid sump; a PTFE seal rated 200 deg C passes -40 deg C cold start but costs lead time. Spec both extremes in degrees C and bar g, not in vague "ambient / process" language [S3].
Hazardous-area certification lines
For zone-classified sump service the four-line block on the RFQ should read: "ATEX II 2 G Ex ia IIC T4 Ga or IECEx equivalent; CSA Class I, Div 1, Groups C and D; ambient -40 to +80 deg C; certificate numbers to be quoted" [S1]. Both ATEX and IECEx approval on the same probe avoids the regional requote when a unit ships to a plant in the Gulf and the same frame is also stocked for a North American EPC package [S2].
Protection type drives price more than sensor type. Intrinsic safety (Ex ia) is the cheapest, but it limits loop power to roughly 0.5 W and forbids long trunk runs above a few hundred metres. Flameproof enclosures (Ex d) carry higher power budgets and survive hot-work zones but add a heavy stainless or aluminium housing, a certified cable entry, and a heavier mounting bracket. For a typical indoor chemical sump the safer default is Ex ia with a passive barrier in the safe area; for an outdoor oil-and-gas drain sump with a hot work permit policy, Ex d is more common. Mark both zones on the same line so the vendor can quote a single instrument that satisfies the worst case [S2]. Sump ambient often runs higher than the loop ambient because the head is over a heated vessel, so a 70 deg C ambient rating is borderline and an 80 deg C rating is the practical floor for many indoor refineries and chemical plants [S1].
Output, protocol and electrical lines
Default the output block to "4-20 mA two-wire with HART 7, 24 VDC loop-powered, reverse-polarity protected" [S3]. 4-20 mA with HART is the only protocol that works on every DCS, PLC and wireless gateway from Honeywell, Emerson, ABB, Siemens, Yokogawa and the lower-tier Indian and Gulf integrators that handle most sump retrofits [S2][S3].
Foundation Fieldbus and PROFIBUS PA are physically incompatible with HART on the same pair, so do not list all three in the same line and force the vendor to pick a card variant. WirelessHART is acceptable for an inaccessible sump but the battery life arithmetic has to go on the RFQ: 1 Hz update with a 19 Ah primary cell is roughly 10 years, and below 0.5 Hz update to stretch that the level reading stops being useful for pump control. A second mA output for an analogue backup is rarely worth the cost on a sump, but a relay or a switch output for high-high level interlock is a clean add-on. The EMC, surge and lightning protection lines belong here too; outdoor sumps near fin-fan coolers see field surge events that take out unprotected loops inside 18 months. A surge arrester on the same line costs little relative to the requote cycle.
Wetted materials, process connection and blanking
Wetted material defaults to 316L stainless with PTFE or EPDM seal, but write the process chemistry on the RFQ rather than the material, because the vendor often has a lower-cost option that is rated for the stated chemistry and fails an unstated one. For hydrochloric acid, sodium hypochlorite and hot caustic a PVDF antenna or a PTFE-faced stainless antenna is the durable answer; a bare 316L face will pit inside a year in 10% HCl at 50 deg C [S3].
Process connection line is the second-biggest requote trigger. Threaded 1-1/2 inch NPT, threaded 2 inch NPT, flanged 2 inch 150# RF, and flanged DN50 PN16 are the four options that cover roughly 90% of sump installations. Anything else, including sanitary tri-clamp on a chemical sump, forces the vendor to quote a custom plate. On a sump, prefer the flange over the thread: a flanged 2 inch 150# RF connection aligns with the same gasket inventory that the rest of the plant already stocks, and a threaded connection on a vibrating sump loosens over time. State the full measuring range, then state the blocking distance (also called blanking distance) the vendor has to guarantee. 80-GHz radar typically delivers blocking distances under 100 mm, but a sump with a stilling well or a coaxial probe sits inside a metal tube and the blocking distance behaves differently. Writing "blocking distance 100 mm max, with dead-band clear of high-high set point" on the RFQ is the single line that prevents the most commissioning disputes [S1].
Selection: 80-GHz non-contact vs 26-GHz vs guided wave
For sumps the comparison comes down to four criteria: minimum dielectric, narrow-tank performance, mechanical vulnerability in a drain pit, and price. 80-GGHz non-contact radar is the best fit for dielectric above about 1.8, narrow sumps with internal piping, and clean chemical service, at roughly 1.4-1.8x the price of a 26-GHz set. 26-GHz non-contact radar is acceptable for dielectric above 2.5, larger sumps above 2 m diameter, and budget-driven retrofits. Guided wave radar (GWR), a probe-based design covered in detail at the guided wave radar level reference, is the only credible answer for dielectric below 1.8, high-foam sumps, or sumps where a stilling well already exists, because the probe concentrates the microwave energy and rides through foam that defeats a free-space beam [S1][S2].
Selection in one line: 80-GHz non-contact for clean chemical sumps, 26-GHz non-contact for dirty water and oily-water sumps above 2 m diameter, and guided wave for hydrocarbon, foam and very-low-dielectric duty. Add a TDR level meter option when the sump is a condensate drain with a low dielectric and a tall standpipe, and treat the standard radar level meter specification as the procurement baseline before any guided-wave or TDR branch. For comparison, the sump pump side of the duty is covered separately because the pump-end and the level-instrument end are usually on different RFQ schedules.
Use cases, failure modes and procurement signals
Three live use cases frame the typical RFQ. NTPC awarded a guided wave radar level transmitter contract for a deaerator on 30 June 2026 to an Indian OEM with a line value of roughly 4.9 lakh INR, which is the lower bound on a single-probe GWR package in 2026 [S4]. A regional Gulf EPC is buying 80-GHz non-contact radar as the default for chemical and oily-water sumps because the same ATEX/IECEx certificate covers all of its regional sites [S2]. Indian process plants serving refineries, water and effluent treatment, chemicals and solvents, and boilers and utilities all source from local Faridabad-based manufacturers offering 4-20 mA HART level transmitters with HART 7 protocol [S3].
The three failure modes that drive warranty returns on sump duty: foam lock, condensate build-up on the antenna face, and sidewall reflections in narrow sumps with internal piping. Foam lock is mostly a 26-GHz problem; 80-GHz with FMCW plus a dynamic echo algorithm rides through light foam and fails on heavy black foam regardless of frequency, which is the case for guided-wave radar instead. Condensate build-up on a flat PTFE face is the most common field complaint, and the answer is a flush-mount antenna with a PTFE lens, not a horn. Sidewall reflections are killed by the 3-4 degree beam of 80-GHz radar in sumps down to about 1 m diameter; below 1 m, switch to guided-wave or install a stilling well. Track the 80-GHz approval date in [S1] and the NTPC deaerator award in [S4] as the two live procurement signals that will refresh over the next quarter, and treat the EchoBeam certification in [S1] as the working reference for any RFQ that has to be issued in the next 60 days. For a related process-side spec problem on the cleaning side, tank cleaning machine selection for tunneling covers the rotating-nozzle duty that often sits downstream of a sump.