City Technology (UK) has released the new generation of two of its most popular gas sensors, the 4CF+ carbon monoxide sensor and the 4HS+ hydrogen sulfide sensor. The existing 4CF and 4HS sensors are widely used by the leading global manufacturers of single and multi-gas detection instruments for life safety applications. The latest designs build on the feedback gained from the tens of millions of devices in the field to offer
significantly reduced calibration times, improved reliability, reduced sensitivity variation between devices and complete backwards mechanical compatibility with previous generations.
A number of design improvements and highly automated volume manufacturing and test techniques have contributed to the new sensors’ enhanced performance. All pins are gold plated, lowering contact resistance with the socket and improving reliability in use, particularly in situations where the instrument is likely to be subjected to shock or vibration. The ultrasonic welding of the internal current collector wires has been improved to give a higher quality, more uniform weld, improving reliability and reducing early failures. At various stages during the manufacturing process, 24 different parameters are tested, each stage of the assembly process is optically monitored and automated part placement reduces variations between devices, ensuring error free assembly.
A 100% leak test on the electrode sealing is an integral part of the manufacturing process, resulting in a significant increase in field reliability by eliminating one of the more common failure modes found in sensors manufactured by others. More than ten million units have been shipped to date; the overall return rate from the field is an exceptionally low 0.006%, mainly because of the pre-emptive testing carried out at every stage of manufacturing. The latest generation promises even better reliability.
