A precision all-mechanical hygrometer that offers dependable accuracy. Intended for indoor use, above freezing level.
Each of these individually selected and tested instruments has a unique serial number and is tested at 3 points at the factory before shipment. This is an elegantly simple design, hand made by German craftsmen, with five secured internal calibration points.Background
This instrument measures the relative humidity of the atmosphere with high precision (These are 3%, to get to 1% costs more than $1,500. Some bargain priced devices do not work at all!). 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 and instruments.
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 the same high precision and fast response time without that required maintenance.Installation
Relative humidity is closely correlated to and dependent upon air temperature, so it provides best data when not exposed to rapidly changing temperatures. 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 than average.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.