Part Number: 65-1020-xxx (xxx refers to gas detected)


Designed for cost effective reliability the C-Guard offers significant value for money in the commercial carp park and HVAC markets. Containing advanced processor and logic this transmitter allows for rapid calibration and simple repairs.

List of Benefits

  • Lowest cost of ownership
  • 45 seconds to calibrate
  • Zero stability logic
  • One man calibration
  • AS1668.2 Auto test
  • Non intrusive calibration
  • No alarm calibration
  • zero gas activation test
  • Simple user options
  • One board does all
  • No tool calibration
  • Fully programmable processor control
  • Vandal proof high impact housing
  • Sensors protection
  • Water resistant IP 65 design
  • Two year warranty


Our engineers have developed high end electronics and a program that monitors the sensor’s outputs and is tailored to and pre-programmed for many different gas types. The program and electronics process the sensor’s output trends and calculates accurate and stable readings. This is transmitted back to the processor using the industry standard 4-20mA.

Mechanical Design

One card to suit all applications is the philosophy. Many of our customers are in remote locations around the world and holding stock for all the different kinds of detectors and ranges that they have on site
is expensive and difficult to manage. In the C-GuardTM design this card had to be easily configured for the different gasses, ranges, sensors styles and must have enough program memory to hold the logic for
each type of gas. Our engineers were able to achieve all this, with enough resources still available to implement many future features.
Each card will be simple to upgrade as needs change.
Housing is an IP 65 strengthened high impact polymer, which is UV stable and is virtually indestructible. The design of the housing was to meet the most challenging conditions encountered. Grey coloured to blend in with the walls in car park application.

End user Features

  • No tool calibration or set up. No screwdrivers, No meters, no special programming tools required to calibrate to comply to AS1668.2
  • No alarms during calibration:
    • When in the calibration mode the C-GuardTM locks the output signal at zero gas reading until the calibration process is finished. Our engineers have implemented a fail-safe logic to maintain constant monitoring.
  • Zero gas activation test:
    • The C-GuardTM logic has a special activation mode. Once entering this mode the mA output is raised to 12mA for 5 minuets. This allows activation of vent fans or alarms to test the system without wasting expensive test gasses. Again bringing down the total ownership costs.

Available Models/ Parts

65-1020-CO C-Guard CO detector 0-100pm
65-1020-CO-1 C-Guard CO detector 0-150pm
65-1020-CO-2 C-Guard CO detector 0-200pm
65-1020-NO2 C-Guard NO2 detector 0-10ppm
65-1020-NO2-1 C-Guard NO2 detector 0-20ppm

Gases Detected

Carbon Monoxide (CO) 0 to 100 ppm 100 ppm
Carbon Monoxide (CO) 0 to 150 ppm 100 ppm
Carbon Monoxide (CO) 0 to 200 ppm 100 ppm
Nitrogen Dioxide (NO2) 0 to 10 ppm 5 ppm
Nitrogen Dioxide (NO2) 0 to 20 ppm 10 ppm
SpecificationDetail Description
Typical range of Gases Detected (Auto, Cal Gas)
Carbon Monoxide (CO) 0 to 100 ppm 100ppm
Carbon Monoxide (CO) 0 to 150 ppm 100ppm
Carbon Monoxide (CO) 0 to 200 ppm 100ppm
Nitrogen Dioxide (NO2) 0 to 10 ppm 5 ppm
Nitrogen Dioxide (NO2) 0 to 20 ppm 10 ppm
Analogue OutputTwo wire 4-20mA
Indication3 LED indication of status
Input Power10-30VDC
Response Time90% full scale response in less than 40 seconds sensor dependent
Operating Temperature -20˚C to +50˚C
Humidity Range0-95% non condensing
Accuracy±5% of reading
Repeatability±1% of reading
Sensor style4 series plug in sensors
CalibrationNon intrusive push buttons, no screwdrivers or meters needed
DriftLess than 5% signal loss per year
AS1668.2 test5 minutes operation at 12mA output
Dimensions140mm x 56mm x 100mm (125 including cable gland)
EnclosureHigh impact UV stable Chemical resistant Nylon
IP RatingIP65
Warranty2 Years on sensor and electronics for CO & H2S, 1 year on all other sensors

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