Here you will find the Frequently Asked Questions (FAQs) for Aeroqual’s Fixed Indoor Air Quality Monitors. For your reference the products discussed are shown below.

  • Series 900 Fixed Gas Monitor

    Series 900 – Fixed Indoor Air Quality Monitor

  • Series930_with-optional

    Series 930 – Fixed Indoor Air Quality Monitor

  • SM70 Fixed Gas Monitor

    SM70 – Fixed Indoor Air Quality Monitor

1. What are the different sensor head types for fixed monitors?

The Series 900, Series 930 and SM70 Fixed Indoor Air Quality Monitors are compatible with different types of sensor heads.

  • Series 900 fixed monitors are compatible with Type 1 sensor heads (interchangeable)
  • Series 930 fixed monitors are compatible Type 2 sensor heads (removable/ replaceable)
  • SM70 fixed monitors have user-defined sensor modules (removable / replaceable)
Ozone Sensor

Type 1 sensor head

Ozone Type 2

Type 2 sensor head

2. What are the different gas sensor heads available for the fixed monitors?

Series 900 Fixed Monitor

The Series 900 Fixed Monitor is compatible with all available gas sensor heads in our range.

To view the full list, visit the Series 900 Fixed Monitor product page, or view the Portable and Fixed Monitor Sensor Spec Sheet.

Series 930 Fixed Monitor

  • Ammonia Sensor 0-100ppm
  • Carbon Monoxide Sensor 0-25ppm
  • Carbon Monoxide Sensor 0-100ppm
  • Chlorine Sensor 0-10ppm
  • Formaldehyde Sensor 0-10ppm
  • Methane Sensor 0-10000ppm
  • Hydrogen Sulfide Sensor 0-10ppm
  • Nitrogen Dioxide Sensor 0-1ppm
  • Ozone Sensors 0-0.05ppm, 0-.15ppm, 0-0.5ppm, 0-10ppm
  • Sulfur Dioxide Sensor 0-10ppm
  • Sulfur Dioxide Sensor 0-100ppm
  • VOC Sensor 0-25ppm
  • VOC Sensor 0-20ppm
  • VOC Sensor 0-2000ppm

SM70 Fixed Monitor

Ozone sensor modules:

  • 0-0.15ppm
  • 0-0.5ppm
  • 0-10ppm

3. What are the different enclosure ratings of the fixed monitors?

Series 900 Fixed Monitor

The Series 900 is a base unit and does not have an enclosure.

Series 930 Fixed Monitor

The Series 930 enclosure is Polycarbonate/ IP41* NEMA 2** equivalent.

*IP 41 Rating: Protected from tools and small wires greater than 1 millimeter. Protected from condensation.

**NEMA 2: Indoor use to provide a degree of protection against a limited amount of falling water and dirt.

SM70 Fixed Monitor

The SM70 Fixed Monitor enclosure is Polycarbonate/ IP20* NEMA 1** equivalent.

*IP20 Rating: Protected from touch by fingers and objects greater than 12 millimeters.

**NEMA 1: Indoor use primarily to provide a degree of protection against contact with the enclosed equipment and against a limited amount of falling dirt.

4. Why are two monitors placed side by side giving different readings?

Individual sensor heads or sensor modules may vary in their readings for many factors, both environmental and related to the sensors themselves.


Calibration and age is an important factor. Over time, and with use, the calibration drifts. Sensor heads or sensor modules should be regularly tested and calibrated to ensure their correct operation. Calibration conditions, such as humidity, will also affect readings if non-factory calibrations are performed.

External Interference

Sensor heads have a clean stainless-steel mesh to filter out dusts. If this becomes dirty over time the sensor head will start to read incorrectly and will need to be replaced. Target gases such as ozone are highly reactive. Ozone will rapidly react with organic compounds and surfaces such as walls, flooring, plastic testing chambers and people. Concentration gradients are common in rooms and are greatly influenced by air movement and mixing. Concentrations may be lower near walls and surfaces or in areas with low air.

5. How do I calibrate my Fixed Monitor sensor heads?

We recommend that sensor heads be calibrated at least once a year.

Series 900 Fixed Monitor – Type 1 Sensor Head

    1. Factory calibration. Return sensors to Aeroqual for a multi-point calibration and new calibration certificate. Please contact our technical team.
    2. Manual calibration. Gas sensors only. Please refer to our page on portable monitor calibration.

Series 930 Fixed Monitor – Type 2 Sensor Head

Factory calibration. Return sensors to Aeroqual for a multi-point calibration and new calibration certificate. Please contact our technical team.

SM70 Fixed Monitor Ozone Sensors

The sensor board must be replaced when the SM70 Fixed Monitor Ozone sensor is due for calibration. Please contact our technical team, and provide the serial number of your monitor.

6. How can I configure the Series 900 and Series 930 in my settings?

The Series 900 / Series 930 alarm and 4-20mA output scale settings can be configured via the Fixed Monitor Configuration software. The PC software can be found on the product software support page.

  • Plug in and install the USB to RS485 converter into your computer
  • Wire the RS485 outputs into the instrument using table above
  • Install the Aeroqual Fixed Monitor Configuration PC software
  • Power up the instrument
  • Run the Fixed Monitor Configuration software
  • Select Unit by entering the Port ID of the instrument you wish to modify and click on Download to download the unit’s current values

7. How do I configure the alarm settings?

Series 900 and Series 930 Fixed Monitors

High alarm and low alarm set points can be configured by entering the required activation set point on the main menu.

SM70 Fixed Monitor

The SM70 sensor module can be used as a simple gas sensitive relay switch to control devices or activate alarms using the on-board relay. Alarm or control points cannot be changed by the user and must be defined when ordering.

8. What are the different output types?

Series 900 and Series 930 Fixed Monitor

Analogue output: 4-20mA (opto-isolated), 12-24V
Digital output:      RS232 and RS485

SM70 Fixed Monitor

Analog output:    0 – 5 VDC (8 bit)[AO1] / 0-1.5V (UZ sensor board)
Digital output:     RS232 and RS 485
Relay output:       24V; 5A(max.)

9. Can I use these the fixed monitor with my own software?

The user guide for each of the Fixed Indoor Air Monitors contains the relevant protocol commands for integrations into third party systems. User guides can be found on the Technical Documents page.