The Hair Hygrograph is designed for measuring & recording atmospheric relative humidity as function of time on recording chart. It is used in the meteorological service as also in cold stores, spinning mills, pharmaceutical
factories, telephone exchanges & pollution control equipment.
Hair Hygrograph gives a record of relative humidity on recording paper.
. measurement of relative humidity hygroscopic properties of human hair & its ability of changing the length according to the quantity of water vapour present in the ambient atmosphere is used. The hair strand element is fixed by means of a holder. One end of the holder is fixed to the bracket while the other end is movable by means of tension spring and adjusting screw. Hair strand is hooked at the center to the link mechanism. The· change in length of hair element is transferred to the pen arm by special cams. Due to the earn mechanism arrangement we get a linear scale on the graph. Recording pen draws the graph of relative humidity against time on the chart.
The arms of recording pens are supported in articulated joints with slant axis that makes possible uniform & constant pressure of the pen tip on the chart drum. Precision clockwork is set inside . the recording drum. The precise make of all
components of clockwork & recording mechanism ensures high accuracy and longer field-life.
Recording chart No. DH -1 for Daily type, Set of 100 charts is supplied with instrument.
Technical Specification :
Sensing Element Hair Strand
Range 0 to 100 % RH
Accuracy ± 2% (Above 20%)
Recording Resolution 1 %
Drum Diameter 933 mm
Housing Material FRP/ Aluminium enclosure with window
Recording Mechanism Drum driven by Quartz Clock