Which Gas Sensor Do I Need?

Which Gas Sensor Do I Need?

The Honeywell City Technology industrial gas sensor range is designed to measure a variety of oxygen depletion, toxic and combustible gases, to help keep workers safe in harsh commercial and factory environments. In this article we take a closer look at the features, functionality and applications of each sensor type manufactured by one of the world’s leading names in gas detection. With over 45 years’ experience, the range includes over 300 electrochemical, catalytic bead and optical sensing products detecting 28 common and exotic gases.



Honeywell iSeries digital gas sensors are next-generation ‘plug and play’ intelligent sensors that boast a digital interface and five-year operating life. With numerous built-in smart diagnostics, the iSeries uses intelligent features such as digital traceability and predictive calibration, as well as early warning for sensor malfunction and end of life indication, to decrease downtime and cost of ownership.

Their ease of integration, combined with pre-calibration, drives a significant benefit to OEMs and users in terms of integrating the gas detector sensors easily into instruments.

iSeries multi gas detector sensors target the following gases: Carbon monoxide, hydrogen sulphide, oxygen, sulphur dioxide and combustible gases & vapours. These sensors are often fitted within instruments such as portable life safety devices and hand-held gas detectors.

With an industry warranty of two years from date of dispatch, Honeywell iSeries simplifies instrument design and speeds development.


1 Series1 seriesHoneywell 1Series analogue gas sensors are unique; compact square sensors designed to meet the global requirement for thinner, more lightweight gas detectors. At 1/3 the height of traditional gas sensors, the 1Series has turrets to mount into the front of an instrument to minimize instrument height. The revolutionary design simplifies target-gas access to the sensor face and features an option for a replaceable external membrane.

1Series sensors target the following gases: Carbon monoxide, hydrogen sulphide, oxygen, sulphur dioxide and combustible gases.

These gas detector sensors are often fitted within instruments such as portable life safety devices and industrial gas leak detectors. 1Series gas sensors excel in challenging temperature and humidity extremes, such as those found in industrial gas applications.

Engineered with an operating life of five years, Honeywell has designed the sensor platform for the future.

3 Series3SeriesProductImage_6de167b0-f046-4a45-85c5-2217b09dfc1e

The 3 Series is City Technology's original gas sensor range for oxygen and toxic gases. An industry standard for portable industrial safety gas detection, 3 Series offers a one- to five-year life. A wide variety of sensors are available in this format and can be supplied with 4 mA to 20 mA and mV transmitter boards. The 7 Series is the natural replacement for this first generation range.

4 Series4 seriesCity Technology’s 4 Series gas sensors are large, robust and durable in design and an industry standard for portable gas detectors and fixed detection in safety and emissions applications. The range detects oxygen and toxic gases, an infrared version for hydrocarbons and fully-certified pellister sensors for combustible gas detection. Additionally, a seven-year life for the 4oXLL for emission applications.

5 Series5 seriesThe 5 Series range of premium gas sensors has been designed to ensure optimal performance within the harsh environments of flue gas analysers and combustion efficiency monitors. Sensors are available for oxygen, carbon monoxide, nitric oxide, nitrogen dioxide and sulphur dioxide, along with a hydrogen-compensated carbon monoxide sensor.

 High capacity filters and electrodes make the 5 Series suitable for use in emissions applications, along with a fast response and recovery time and durability in harsh environments.

7 Series7 seriesCity Technology's 7 Series range is suitable for general gas detection applications including oxygen and toxic gases and are suitable for use in portable or fixed gas detectors and medical gas applications. They offer an extensive range of oxygen and toxic gases.

 Lower in height than traditional gas sensors, 7 Series is designed for portable and transportable applications across a wide range of gas detection.


AQ3 Series

Growing global awareness has increased the focus on air quality in regard to current contaminant levels, as well as how to better manage air quality.

 These reliable gas sensors detect a variety of gases including carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3) and sulphur dioxide (SO2). They are used mainly for ambient environmental monitoring as they have a high correlation with air monitoring stations and also offer high resolution with a low detection limit.

AQ3 gas sensors are designed for operation in a wide range of environments and harsh conditions. Whilst they are designed to be specific to the gas they are intended to measure, they will still respond to some degree to various other gases, achieving individual compensation for temperature and cross sensitivity.

Available with or without a module board, the AQ3 Series offers high resolution and a low detection limit. The custom-built low noise board achieves high accuracy under ppb level.


AQ7 Seriesaq7The demand for lower-cost, easily transportable solutions for environmental applications has grown substantially as public awareness and demand for healthier breathing conditions has increased, leading to a growing need for monitoring air quality across cities.

AQ7 Series gas sensor are well suited for these environmental applications and detect carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3) and sulphur dioxide (SO2). Honeywell has designed the AQ Series with algorithmic compensation that gives users very high resolution, a low detection limit and long-term stability. Highly accurate, AQ7 has a high correlation with air monitoring stations.

AQ7 Series gas sensors are designed to be highly specific to the gas they are intended to measure, they will still respond to some degree to various other gases, achieving individual compensation for temperature and cross sensitivity.

AQ3 & AQ7 Applications:

  • AAQ mini stations, portable AAQ systems, AAQ UAVs
  • Aerial vehicles
  • Urban air monitoring networks
  • National air monitoring networks
  • Roadside air monitoring
  • Industrial perimeter monitoring
  • Environmental impact assessments
  • Research and consultancy projects
  • Short-term hot spot monitoring

CRIR Series:

Honeywell CRIR Series CRIR E1 lowres photoThe CRIR Series are single channel, non-dispersive infrared (NDIR) sensors. Within the CRIR M1 and CRIR E1 is a sensing chamber with an infrared source at one end and a detector fitted with an optical filter at the other end. The source emits radiation at wavelengths which include the absorption band of carbon dioxide (CO2).

Small in size, CRIR are ideal for normal indoor applications as they are maintenance-free. Offering consistency and repeatability, they easily integrate and deliver enhanced long-term stability. Other features include automatic baseline correction, temperature compensation and UART digital interface.

Potential applications cover HVAC, demand controlled ventilation, indoor air quality (IAQ) measurement, air purification systems and smart /IoT (Internet of Things) systems.


Sensoricsps-siot-citytech-sensoric-sensor-3Sensoric toxic gas sensors have gained worldwide recognition for excellent performance, particularly for detecting exotic gases. Sensors are available in a small ‘mini’ housing, 4- and 7-Series format without the need for any adapters. Sensoric sensors are also available with 4 mA to 20 mA transmitter boards.

sps-siot-citytech-microcel-3MICROceL and MICROpeL are City Technology’s smallest, most compact sensors. The range includes carbon monoxide, hydrogen sulphide and fully-certified combustible gas sensors.

OTHER COMBUSTIBLES:sps-ast-other-combustibles-4Standard Pellister catalytic bead pair, miniature size with lower power consumption suitable for portable gas detection instruments and high power consumption ideal for fixed gas detection instruments. Versions with higher poisoning resistance are available. Some variants are also ATEX certified for hazardous area applications.

The Benefits of Shawcity

Shawcity are Strategic Channel Partners of City Technology and we ship across the EMEA region to thousands of customers each year. We offer 300+ sensor products detecting 28 common and exotic gases, all manufactured in the UK, Germany or China.

We’re here to help. Quantity breaks are available for larger orders, while the minimum order is one!

View our range of gas sensors here.

Contact us for further information. Our team offers technical advice with one-on-one account support.

Telephone: 01367 899553

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