Hygrometers are single purpose instruments that measure the amount of water in the air. They actually measure the relative humidity, which is expressed as a percent of comparing the actual water in the air and the amount of water the air could contain if it was completely saturated. While we can at least try to guess what’s air temperature at the moment even without looking at a thermometer, it is much harder if not impossible to measure humidity without a hygrometer. Keeping a stable humidity level can be just as important as keeping the right temperature. High humidity can damage stored food, medicine, etc… just like high temperature can. The only difference is that without a hygrometer you really have no way of knowing that something’s wrong!
Older mechanical hygrometers show only the present relative humidity. Some more expensive mechanical hygrometers record the humidity on a piece of paper so that you get an actual printed chart, increasing the hygrometers’ usefulness – chart recorders. But hygrometers alone generally only show the present RH level and, unless we spend all of our time watching the readout, they tell nothing about possible humidity fluctuations. So how do you determine that? Analog chart recorders or digital data loggers record the RH level over time. They are great improvements over the older mechanical hygrometers.
Newer recording hygrometers can be chart recorders or data loggers. Using chart recorders or data loggers that record humidity you can determine if your stored inventory (i.e. food, medicines, electronic materials) are being stored in the proper environment. And If they have an alarm with them they will alert you if something goes wrong so you can take action.
Example: Consider this situation – your computer room is a subject to frequent humidity changes (due to improper air conditioning, for example). Everything’s all right most of the time but occasionally the humidity sharply rises and falls. If no one is present during these times you will never realize that the environment is changing. This can be a real problem for computers. Too low humidity can lead to static discharges, and a static discharge can completely destroy a hard drive or microprocessor.
A recording hygrometer such as a chart recorder or data logger will keep a record of what happened but are not able to trigger alarms when a dangerous trend occurs. For that you need a data viewer such as the TV2, so a text, Email or phone call can alert you if the humidity begins to drop.