Safety Through Training and Assessment




Single chamber ionisation particle detector


Radioactive source Krypton85 inert gas with 10.7 year half live


Robust and resistant to harsh environments – Salt spray and acid fumes


Extreme sensitivity


Able to detect smoke particles in air with high flow rate


4 to 20mA, 2wire interface available






Becon® trade name is derived from the main features of the detector using a Beta radiator (radioactive source) and conductive plastic components.


A 316 Stainless Steel enclosure provides the physical strength to the detector. Nylon coating protects the enclosure against acid corrosion. Conductive elements consist of conductive plastic parts that can not corrode. The electronic circuitry is encapsulated to prevent the ingress of moisture.


The detector chamber is ionised with a Beta radiator - Krypton85 gas isotope contained in a glass tube. The ionised air is causing a flow of a small current, typical 0.5-9A or 0.5nanoA between the Cathode and Anode electrodes. The Gain of the detector is set to give an output signal of 90%.

In the event of particles in the spectrum of 0.1 to 10 microns entering the smoke chamber the signal will be reduced according to the number of particles entering.



The detector is most sensitive to particles in the invisible spectrum. Flammable material releases particles in the form of aerosol before ignition. Clean burning flames also releases invisible particles. (Test – Burning match) Particles released from 1gram of printer paper (Half A5 sheet) in 1 cubic meter of air will saturate the detector signal at 10%


Chamber current is directly proportional to the radiation from the Krypton85 source. Chamber radiation is affected by the decay of the source and contamination on the surface of the glass tube. The gain control is used to compensate for these losses. Increase in gain will increase the sensitivity of the detector.



Several activities my result in nuisance alarms. These are typically diesel fumes from vehicle and heavy machinery used in mining. Fumes from blasting, welding etc. Sudden changes in humidity caused by weather changes or washing down an area upstream of the detector. Major change in ventilation.

Sensitivity for the early warning of FIRE can not be achieved without generating nuisance alarms when using basic alarm trip level processing provided by SCADA systems.




Zero tracking of scaled value to compensate for drift caused by environmental/mining condition changes, change in ventilation flow, contamination of radioactive isotope and ageing of isotope.


Complex rate of change algorithm to discriminate between nuisance activity and FIRE.


User friendly parameter changes to optimise alarm sensitivity without compromising generating nuisance alarms.


Comprehensive integrated reporting to determine System Integrity

Can be washed in water to remove contaminants that reduces the chamber current, resulting in instability


Ex ia Intrinsically Safe Certified


Gain of detector controlled by external set screw – Set nominal background to 90% of signal value


Test points on Junction Box