Rosemount OCX8800 Oxygen & Combustibles Transmitter

Close-coupled extractive flue-gas transmitter that measures net oxygen and combustibles equivalent (COe) in one package — zirconia O2 cell plus catalytic-bead COe sensor for fired equipment trim up to 2600 °F (1427 °C).

Key advantages

O2 + COe in one transmitter — Zirconia oxygen cell with catalytic platinized beads plus catalytic-bead combustibles sensor with dilution air.
Wide flue temperature class — Probe materials cover 316L SS to 1300 °F, Alloy 600 to 1832 °F, ceramic to 2600 °F (1427 °C).
Field-selectable spans — Net O2 0–1% to 0–40%; combustibles 0–1000 ppm to 0–5% via HART or local operator interface.
Plant communications — Isolated 4–20 mA O2 and COMB outputs with HART; FOUNDATION Fieldbus option; AMS/PlantWeb compatible.
Maintainable in place — Field-replaceable sensors, air-purge calibration cycle, optional factory auto-calibration panel, internal/in-situ filters.

Typical applications

Boiler, process heater, and furnace excess-O2 trim with combustibles cross-check.
Thermal oxidizer and fired-equipment flue-gas O2/COe monitoring.
Sites that need HART or FOUNDATION Fieldbus diagnostics from the control room.
Combustion loops where incomplete-combustion detection is part of the control strategy.

Selection guide

Probe length / material — Order-string lengths from about 18 in to 9 ft; match material to process temperature class.
Communications — HART analog vs FOUNDATION Fieldbus; confirm LOI need.
Electronics mount — Integral vs remote electronics; auto-calibration panel yes/no.
Hazardous-area variant — Standard OCX8800A vs explosion-proof / hazardous-area OCX8800C family when the area class requires it.

Common mistakes

Treating OCX8800 as O2-only — COe combustibles sensing is part of the published function set.
Ordering probe material that is below the actual flue temperature (ceramic class needed above Alloy 600 limits).
Assuming the auto-calibration panel is included without selecting that option.
Skipping hazardous-area model selection when the install is classified.

When to RFQ / what to tell us

Flue application, process temperature, probe length/material, and O2/COe spans.
HART vs FOUNDATION Fieldbus; integral vs remote electronics; LOI / auto-cal needs.
Hazardous-area requirement; quantity; ship-to country.

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Specs

Spec	Value
SKU	46394
Brand	Rosemount (Emerson)
Model	OCX8800
Product type	Oxygen and combustibles (COe) transmitter
Net O2 range	0–1% to 0–40% (field-selectable via HART or LOI)
Combustibles range	0–1000 ppm to 0–5% (field-selectable)
O2 accuracy	±0.75% of reading or 0.05% O2, whichever is greater
Combustibles accuracy	±50 ppm
Response (test gas)	O2 10 s T90; combustibles 25 s T90
Process temperature (by probe)	316L SS 0–704 °C; Alloy 600 0–1000 °C; ceramic 0–1427 °C
Ambient (sensor / electronics)	Sensor housing −40 to +100 °C; electronics −40 to +65 °C
Outputs / protocols	Isolated 4–20 mA O2 and COMB (HART); FOUNDATION Fieldbus option
Line voltage	100–240 VAC, 50/60 Hz
Max process pressure	8 in water column (OEM PDS)

Documents

FAQ

Q: What does OCX8800 measure? A: Continuous flue-gas net oxygen and combustibles equivalent (COe) in a single transmitter.

Q: What process temperature can it handle? A: Up to 2600 °F (1427 °C) with the ceramic probe class; lower limits apply for 316L and Alloy 600 probes.

Q: What should I send for a quote? A: Probe length/material, O2/COe spans, HART or Fieldbus, electronics mount, auto-cal/LOI, area class, quantity, ship-to.