FIA has just published Fact File 17. Ionisation Chamber Smoke Detectors (ICSD). Applicable Regulations For Manufacturing, Transport and Disposal.

Ionisation Chamber Smoke Detectors (ICSDs) are point-type smoke detectors containing a small amount of radioactive material. This radioactive material is the key to how the ICSD senses smoke. Going back 20-30 years, the ICSD was the primary technology choice for a smoke detection device. This choice was mainly influenced by the relative simplicity of the sensor technology and the fact that photoelectric smoke sensor technology was expensive and not properly understood. The ICSD was considered to be a good general-purpose detector. In the last 10 years, this trend has totally reversed, with photoelectric smoke detectors becoming the preferred choice. This is mainly due to cost reductions in components, better designs and better manufacturing techniques, but also to the regulatory costs now being incurred in the manufacturing, distribution and disposal of detectors incorporating radioactive sources.ICSDs respond well to the visible and invisible particles produced by fast flaming fires. Photoelectric smoke detectors, on the other hand, respond better to the darker smokes produced by smouldering fires and are less sensitive than ICSDs to fast flaming fires. ICSDs still offer, therefore, faster response to certain types of fire risk. Newer technologies, such as combined smoke/heat detectors, carbon monoxide (CO) fire detectors and combined CO/heat detectors, also respond faster than photoelectric detectors to certain types of fire, providing suitable alternatives to ICSDs for many risks and further reducing the need for ICSDs.The availability of alternative detection technologies together with the increasingly stringent regulations and legislation relating to radioactive materials is reducing the numbers of ICSDs sold and this trend looks set to continue