Fixed carbon monoxide (CO) gas detector

Carbon monoxide is a colourless, odourless toxic gas produced by incomplete combustion. It gives no warning of its own, which is why fixed detection is used wherever engines or burners run indoors.

Fixed gas detector in a grey flameproof aluminium housing with a front display, and a remote sensing head on a cable
Selectable ranges
0-500 / 2000 / 5000 / 10000 ppm
Resolution
0.1 / 1 ppm
Response time (T90)
≤15 s

Where carbon monoxide detection gets specified

The places this cell is usually ordered for. The detector body and the wiring are the same in every one of them.

Choosing a range for carbon monoxide

The 0 to 500 ppm range covers occupied spaces. The higher ranges are for flue, furnace and process atmospheres, where concentrations sit far above anything a person should breathe.

Pick the lowest range that still covers the highest concentration you expect at that point. A lower range gives finer resolution around the alarm set points.

Where to mount a carbon monoxide detector

Carbon monoxide has close to the same density as air (relative density 0.97, air = 1), so it mixes into the room instead of settling or rising. Mount the detector at breathing height, about 1.5 m, close to the likely release point.

Keep the detector clear of splashing water, oil and mechanical impact, and leave room around it to open the cover for calibration.

Specifications

One detector body across the whole family. The sensing cell inside sets the target gas and the range.

Target gas Carbon monoxide (CO)
Selectable ranges 0-500 / 2000 / 5000 / 10000 ppm
Resolution 0.1 / 1 ppm
Response time (T90) ≤15 s
Sensor Replaceable carbon monoxide sensing cell
Sampling Diffusion, pump suction optional
Analogue output 4-20 mA, 3-wire (2-wire optional)
Digital output RS485, Modbus RTU
Alarm outputs Two relays, normally open, AC 120 V 0.5 A / DC 24 V 1 A
Supply 24 VDC (12 to 30 VDC), 2 W or less
Display LCD with backlight
Enclosure Flameproof aluminium alloy, IP65
Cable entry M20×1.5 internal thread
Mounting Wall mount or pipe flow-through
Operating conditions -20 to 50 °C, 10 to 95% RH non-condensing
Dimensions and weight 196 × 140 × 91 mm, 1.2 kg

Workplace exposure limits for carbon monoxide

These are United States values. Limits differ by country, and alarm set points are decided by the site against its own regulations and risk assessment.

NIOSH recommended exposure limit (REL)TWA 35 ppm (40 mg/m³) C 200 ppm (229 mg/m³)
OSHA permissible exposure limit (PEL)TWA 50 ppm (55 mg/m³)
Immediately dangerous to life or health (IDLH)1200 ppm

TWA is a time-weighted average over a working shift, ST a short-term limit, C a ceiling that should not be exceeded, and Ca marks a substance NIOSH treats as a potential occupational carcinogen.

Source: NIOSH Pocket Guide to Chemical Hazards: Carbon monoxide

The alarm does not wait for the network

Gas detection has a requirement most sensors do not: the alarm must work when the network does not. The cloud is layered on top of the local interlock, and never replaces it.

Local interlock by relay

Two configurable alarm relays per detector, normally open dry contacts. Fans, solenoid valves and sirens trip locally with no network involved.

4-20 mA into the panel you have

The analogue loop feeds a PLC, a DCS or an existing alarm panel directly, so the detector drops into an installed base without replacing it.

RS485 Modbus into a Genesis controller

The digital reading goes over Modbus RTU into our industrial IoT controllers, on the same bus as the other sensors on the site, and from there to the cloud over cellular.

Cloud record, alerts and API

Concentration charts, threshold alerts to the right person, an exportable log of every excursion, and a REST API for your own reporting system.

Frequently asked questions

Is carbon monoxide heavier or lighter than air?

Neither in any way that matters. Its relative density is 0.97 against 1 for air, so it mixes into the room. The detector is mounted at breathing height, about 1.5 m.

What measuring ranges are available for carbon monoxide?

0-500 / 2000 / 5000 / 10000 ppm, with a resolution of 0.1 / 1 ppm. The sensing cell sets the range, so it is chosen when the detector is ordered.

Is this a carbon monoxide sensor or a carbon monoxide detector?

Both words get used for it. The sensor is the sensing cell inside, which reacts to the gas. The detector is the complete instrument around it: the housing, the display, the alarm relays and the outputs. What is described here is the complete detector, with the carbon monoxide sensor cell fitted.

Do the alarm relays depend on the network?

No. The two relays are driven locally by the detector against its configured set points. Ventilation, shut-off and sirens trip even when connectivity is down. The cloud adds the record, remote visibility and escalation on top.

How does a carbon monoxide detector report to the cloud?

The detector outputs 4-20 mA, RS485 Modbus RTU and two alarm relays at the same time. The Modbus output connects to a Genesis controller alongside the other sensors on the site, and the controller sends the readings over cellular for charts, alerts and the REST API. The analogue loop and the relays keep serving the existing panel and the local interlock.

How often does a carbon monoxide detector need calibrating?

At least once every six months. Calibration is done from the front panel menu by trained personnel with certified gas: a zero, then a span near half of full scale. The sensing cell is replaced at end of life without changing the installation.

Is the detector suitable for hazardous areas?

The detectors are built in flameproof aluminium enclosures designed for hazardous area installation, sealed to IP65. Certification documentation for your market and installation class is scoped per order.

Send us the gas points

How many carbon monoxide points, at what range, and which panel or controller they report into. We come back with the cell and range to specify and how the detectors wire into what is already there.

Talk to us →