Portable Hygrometer Offers Measurement of Dew Point in Hydrogen

Within the power industry it is common practice to use hydrogen as a direct coolant for the generator stator windings. Hydrogen is used because it has an extremely high heat transfer capacity and is much more efficient at transferring heat than any other medium. It is vital that this process can measured and Michell Instruments’ portable Cermax IS, with its hazardous area capabalities, is the ideal solution.

The re-circulating hydrogen removes heat from the generator, transferring it via a heat exchanger into a secondary cooling circuit which uses de-mineralised water. Often this de-mineralised water is then cooled either by sea water or river water, dependent upon location of the power station. As it is not possible to hermetically seal the generator set castings, there is a potential for moisture to ingress from the surrounding air, similarly, as the heat exchanger gradually becomes more porous with age, it too will allow moisture to get into the hydrogen. It is therefore essential that the dew point of the hydrogen is monitored and maintained at a safe margin, as a build up of moisture in hydrogen can lead to a risk of flashover.

Michell’s intrinsically safe portable dew point hygrometer can be used for this type of application as a spot check tool. With raw performance, rugged reliability, fast response and ease of use, Cermax IS (with data logging facility) enables the user to make a quick on-site measurement. With ATEX, FM and CSA certification, the fully self-contained portable hygrometer will allow the user to check moisture content at any point in the process.

Users will usually rate a fast speed of response as a prerequisite for a portable hygrometer. Cermax IS has been designed with this key feature in mind. With an inherently fast Ceramic Moisture Sensor and a minimun volume stainless steel sample housing, Cermax IS has a head start on the competition in this area. If you couple this factor with Cermax IS’s user selectable field operation mode, which allows even ppm level measurements to be made in a just a few minutes, the result is a world-class portable hygrometer with superior performance.

Cermax IS also offers extremely high accuracy and repeatability. The combination of advanced sensor technology and measurement circuitry give Cermax IS a standard measurement from –100 to +20 oC dew point (dp) and indication down to 120 oC and up to +30 oC dp. The advanced portable hygrometer offers a measurement accuracy of +/- 1 oC dp in the range of +20 oC to –59.9 oC dp and +/-2 oC dp in the range –100 to –60 oC dp.

If you would like any further information about Michell Instruments’ advanced portable hygometer, Cermax IS, or any of Michell products, please contact us.