Item #: 103PMH
A precision all-mechanical hygrometer that offers accuracy as good as real hair hygrometer with much less maintenance. Intended for indoor use, above f... [Read More]
Our Price: $171.99
|measuring range: 0 to 100% relative humidity|
|accuracy: ± 3% relative humidity|
|scale graduation: 1% relative humidity|
|Background: This instrument measures the relative humidity of the atmosphere with high precision. Relative humidity is a crucial factor in weather analysis and forecasting and human comfort. The data are also crucial to the safe storage of many products.
This purely mechanical instrument has been a prized product of the Fischer Precision Instrument Company for more than 60 years. It has no electronic components. The sensor element is a specially treated synthetic fiber whose length is sensitive to the humidity in the air. For a given tension on the fiber bundle, the length increases with increasing relative humidity. Changes in its length are then magnified with precision gears to display the relative humidity of the air.
In contrast to real hair hygrometers, which must be chemically cleaned and rejuvenated often, this synthetic-fiber model provides high precision and fast response time with very little maintenance.
Installation This instrument is intended for use indoors at air temperatures above freezing. For the best measure of the humidity, avoid placing the instrument in direct sunlight or in line with strong breezes. Locate the instrument in a place that best represents the average temperature of the local environment. Avoid outside walls that might be cooler than average, and avoid direct exposure to heat sources that would be warmer.
Maintenance: Although it is not strictly needed, if you desire to have the best results and to be confident of your results, it will be beneficial to rejuvenate the fibers once or twice a year. This is done by wrapping the full instrument in a warm damp cloth or towel and letting it sit for 30 minutes or so. This will extend the fibers to their maximum length corresponding to a relative humidity of 95-to-98%.
This is an easy process but in doing so, do not let the instrument come in contact with hot water or with steam as that could permanently deteriorate its performance.
Wrap the instrument in such a way that you can still lift an edge of the towel to see the dial and also retain access to the adjustment screw on the bottom of the instrument, near the vent holes.
If after 30 minutes the dial does not read in the range 95-to-98%, then use the adjustment screw to bring it to that range. Then you can remove the towel and replace the instrument in its normal environment and expect to read an accurate relative humidity in an hour or so. After that, notable changes will be indicated more rapidly.
For home use, if you have the average seasonal variations indoor humidity of say 75% to 50% in the summer and 40% to 25% in the winter, then a good time to rejuvenate would be in the beginning of winter and beginning of summer when the relative humidity is crossing over the 50% range.
For use at sea underway, you might just choose two dates to make the rejuvenation such as the two solstices.
Healthy room environment: It is often considered that 40% to 60% is a healthy and comfortable relative humidity range, and with a hygrometer showing the actual value you may find that added moisture in the winter would be beneficial.