Keywords
Citation
(2003), "Alphasense NOx and chlorine sensors defy relative humidity changes", Sensor Review, Vol. 23 No. 4. https://doi.org/10.1108/sr.2003.08723daf.005
Publisher
:Emerald Group Publishing Limited
Copyright © 2003, MCB UP Limited
Alphasense NOx and chlorine sensors defy relative humidity changes
Alphasense NOx and chlorine sensors defy relative humidity changes
Keywords: Gas sensors, Humidity
Alphasense of Great Dunmow, UK have released two ranges of Nitric Oxide and Chlorine sensors that once again overcome a common deficiency found in previously available product (Plate 5).
Plate 5
Two new ranges of nitric oxide and chlorine sensors from Alphasense
Until now this class of sensor has exhibited poor stability of the zero base line when exposed to step changes in ambient relative humidity. International Health and Safety regulated alarm levels for chlorine are now at 1 ppm for the time weighted average and 1.5 ppm for the Maximum Exposure Limit. Britains HSE is now considering the same exposure levels for nitrogen oxides.
Poor base-line stability results in sensor outputs that exceed these low alarm thresholds when instruments incorporating the sensors are exposed to rapid relative humidity changes. This will occur, for example, when personal monitors are moved from one working environment to another with a resultant false alarm being generated.
Alphasense CL2-A1 and CL2-B2 for chlorine, NO2-A1 and NO2-B1 for nitrogen dioxide, NO-A1 and NO-B1 for nitric oxide incorporate unique electrode structures that provide stable outputs with changes as great as 95 per cent relative humidity (rh) (Figure 1).
Figure 1
Alphasense NO2-B1 humidity transient base line response results for eight
sensors from one production batch
The "A Series" sensors are ideally suited for use in portable instrumentation designed for three areas of application, portable gas detectors for personal protection, portable analysers for stack gas measurement and portable instruments for environmental monitoring.
The "B Series" are designed for use in fixed installation transmitters for applications in the water treatment industry. Commercial and public transport vehide servicing and garaging centres and Engine test facilities.
These sensors augment an established range for other gases now used widely by some of the worlds leading instrument manufacturers.
For further information, please contact: Hugh V. Feldman at Alphasense Ltd. E-mail: hvf@alphasense.com