The Michell Instruments CDP301 hydrocarbon and water dew-point tester is a fully portable, manual-visual dew-point instrument that uses the chilled mirror technique for highly accurate and reliable measurements of both hydrocarbon and water dew point. It is ATEX, IECEx and cQPSus compliant for use in a Zone 1 or 2 Hazardous Area and Class I, Div 1 Hazardous Locations, allowing it to be positioned close to the process sample test point. It is fully portable, simple to set up and, as it is fully self-contained, there is no need to use a separate coolant gas. Unlike older visual-manual dew-point testers, which rely on the operator making observations through a microscope, the CDP301 includes a full-colour interface which shows a magnified view of the mirror surface. It is this optimised display – together with specific illumination techniques – that makes it possible to measure either water or hydrocarbon dew point and log the results. Visible red-spectrum laser light clearly illuminates fine water droplets and ice crystals when targeting water dew point. Broader spectrum white light enables the iridescent film synonymous with HC condensate to be detected with a high sensitivity of up to 5mg/Nm³.
Once the user has observed a layer of condensation form on the mirror surface, the temperature, pressure and dew point are recorded at the push of a button. The video footage and/or still images, along with corresponding data, for multiple measurement cycles is logged for later review either on the instrument’s display or on a PC. The dew-point tester meets the requirements of ASTM D1142 (standard test method for water vapor content of gaseous fuels by measurement of dew-point temperature) and ISO6327 (determination of natural gas dew point using the cooled surface condensations method).
The cooling rate of the mirror surface is precisely controlled to enable sensitive detection and repeatable measurements in accordance with the relevant ASTM and ISO test methods specific to dew point in natural gas. The new Peltier-cooled sensor designed specifically for CDP301 features class leading thermal characteristics to offer cooling depression by up to 70˚C below ambient operating temperature even when performing tests at high analysis pressure up to 100 barg. The CDP301 weighs just 8kg and its rechargeable battery allows up to 8 hours of use, so it can be used with complete confidence in remote locations where access to power is not always guaranteed.