Choices for logging systems are expanding all the time, and defining your application and finding a logger to match it, rather than fitting your requirements to a given logger, dictates the best selection. Take care not to over-specify because this will reduce your choices and increase your expenses. Cost of ownership is not limited to the purchase price of the data logger; you also need to take into account the time and expense needed to maintain the logger on site.

The summer of 2004 might not have set hurricane records, but hundreds of thousands of lives were disrupted by either a hurricane or the threat of one on its way. Improved knowledge of the paths these storms are most likely to take will lead to more accurate advisories and reduce the chances of unnecessary evacuations for hurricanes that don't strike where expected.

The chilled mirror hygrometer (CMH) has been used as a NIST-referenced humidity transfer standard in metrology laboratories for the past four decades. Its principle of operation is simple and elegant. Its totally inert construction, wide measuring span, and high precision have led to thousands of industrial control installations. The proper application of any process monitoring device, and especially a humidity sensor, first requires a good understanding of how the sensor works and its advantages as well as its limitations. That is what this article is all about.

Pumping crude oil tends to take place in some pretty inhospitable locales. Esso Exploration and Production Chad Inc. (operator of a consortium that also includes Petronas Carigali [Chad EP] Inc. and Chevron Petroleum Chad Co. Ltd.) uses a remote airstrip in Kome, Chad, to support its crude oil production operations there. To maintain safe operation of the airstrip, the company needed a better weather observation system to keep tabs on the local conditions.

A few years back, Measurement Specialties, a pioneer in pressure sensing, gained recognition for an aggressive schedule of acquisitions. More recently, the company established MSI Sensors (www.msisensors.com) as a separate division and echoed history as MSI made four significant acquisitions in 2004. In all cases, the acquired companies note the benefits of being a part of MSI's global operation.

This discussion of the operating principles of capacitive, resisitive, and thermal conductivity humidity sensors also addresses their advantages, disadvantages, and applications.

A humidity sensor designed for retrofit into a 1-Wire weather station is powered by and communicates over a single twisted pair.