Moisture Control and Measurement Ltd (MCM) has recently fulfilled a contract to design and supply moisture measurement systems for a new helium recovery plant at BOC Gases plant in the UK.

Just in time quality control and precision of data was of most importance to the client who needed to be able to reliably segregate product with different trace moisture contents despite detecting levels in the sub ppm range within a production environment.

MCM say in order to meet the demanding nature of the helium recovery application, and enable reliable measurements over extended periods of operation, the custom-designed sample systems needed to be engineered entirely from high-grade vacuum fittings and utilise a unique sensor technology which has much faster response and superior stability and repeatability characteristics over previously used moisture sensors.

The new technology centres on a temperature controlled silicon sensor which can be rapidly dried to remove both water and lower volatile contaminants from the sensor surface in a matter of seconds. The added benefit of this approach is that each measurement can be approached from a dry and reproducible starting condition, thereby eliminating hysteresis, on of the most significant sources of measurement uncertainty in humidity analysis.