Dewpoint measurement for compressed air monitoring
July 27th 2007 Michell Instruments is one of the world’s leading manufacturers of industrial hygrometers for dew point measurement, and provides a range of instrumentation for monitoring moisture content and quality. EASIDEW ON-LINE FOR DEWPOINT DEPENDENT SWITICHING Consistent compressed air quality is vital as any contaminates, particularly moisture can have a marked effect on the product quality or equipment operation. Twin column desiccant dryers are commonly used to reduce moisture content (or dewpoint temperature) in compressed air systems. However, these can often be costly in terms of energy used. This is because the switching of columns is performed on a fixed time period, set by analysing the worst case, such as maximum usage. At times when the usage is low the columns maybe switched, too frequently, thus wasting in turn valuable air and energy. To make the process more energy efficient industrial hygrometers (dewpoint instruments) are utilised. The hygrometers monitor the dewpoint of the gas as it exits the dryer, and only when this dewpoint begins to rise towards unacceptable levels are the desiccant columns switched. This process can lead to energy savings of up to 80% with equipment and implementation costs recovered in less than six months Dewpoint dependent switching is now fitted as standard in most modern dryers. Older dryers can benefit by simple retrofit of a suitable hygrometer to replace the existing time-based controller. Michell Instruments offer the Easidew On-line for this purpose. The Easidew On-line is designed to provide continuous measurement of the dewpoint of air or other gases, and utilises the Michell Instruments Ceramic Moisture Sensor to provide stable and reliable measurement. Measurements in the range –100 to +20ºC dewpoint and with an accuracy of +/-2ºC can be provided. The Easidew Transmitter can be installed into systems with pressures up to 400 Bar and provides a 4-20mA signal to the Easidew Monitor via a cable which can be over 50m in length if necessary. The Easidew monitor displays the dewpoint and provides two alarms, perfect for the control of a desiccant dryer. PORTABLE COMPRESSED AIR SPOT CHECKS For plants where continuous monitoring of air quality is unnecessary or not cost-effective Michell Instruments offer the Easidew Portable. The portable dew point hygrometer is compact, easy to use, with fast response, integrated sampling system and traceability to National Standards. It has also been designed to make in-field checks of the dew point in air and gases as simple and quick as possible. For compressed applications that require more features, Michell’s Cermax is the perfect solution. This high specification portable hygrometer gives a wide operating range, extremely fast response and a host of userdefinable features such as data logging and multiple display options. Cermax’s programmable display interface powers up to give an almost instant display of measured dew point. The fully selfcontained portable hygrometer provides a standard measurement range from –100 to +20ºC with indication down to –120ºC and up to +30ºC. Its data logging facility can store up 10,000 measurement points and will store the dew point and a second process variable. DEW-POINT TRANSMITTER FOR CONTINUOUS MEASUREMENT OF COMPRESSED AIR The Easidew Transmitter is designed for ease of use, incorporating all the features you want to make installation and operation as simple as possible. For the first time, dew point measurement is made as accessible as temperature and pressure with this fully configured, calibrated transmitter that can be instantly incorporated into your air or gas management and control system. More articles from Michell Instruments Ltd: | 
