???? 1 .Choose a stand-alone digital hygrometer if constant monitoring is not needed. Standard models also provide temperature information and the maximum and minimum readings over the last 24 hours. Accuracy depends on price, and if accuracy is not necessary (5 percent margin of error), this type of digital hygrometer is inexpensive.

???? 2 .Choose a model with a sensor. If the read-out of the hygrometer will be in a separate space from where measurements will be taken, you need a sensor. The sensor can be attached with a cable or wireless (cables are usually more accurate). This type of digital hygrometer is useful when the sensor will be outside or in an exhibit case, but the user wants to record the measurements in an area with easier access.

???? 3 .Choose a portable, digital psychrometer if you need mobility and quick readings. For some applications, a user will need to move the digital hygrometer from location to location. A handheld, digital psychrometer with built-in sensor is useful for mobility. This instrument will adjust more rapidly to changing environments when moved to provide faster readings.

???? 4 .Choose a datalogger when constant monitoring is necessary. Dataloggers record constant data in user-adjusted intervals that can range from seconds to hours. This is critical in certain situations (such as in humidors or museum exhibit areas) when it is necessary to provide a constant, unchanging (or little changing) humidity level for preservation purposes. Data can be downloaded into a computer to view graphs and tables and alert users to humidity problems.

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