The 230-7020-A Hi-Q Barograph is a precision instrument designed to continuously record atmospheric pressure. The sensor is a 14-cell aneroid bellows assembly made of copper and bronze alloy. One end of the assembly is attached to the instrument base, while the other is linked to the recording pen arm. As changes in atmospheric pressure cause the bellows to expand or contract, the pen moves up or down on the chart. The linkage between the sensor and the pen includes a bimetal strip to compensate for changes in ambient temperature which also cause bellows movement. Other components of the linkage are chrome plated brass or stainless steel.
The recording span of the barograph can be adjusted for altitudes between sea level and 12,000 feet. This is easily done by means of a knob which increases or decreases the height of the pivot in the linkage. Fine adjustments are made on the pen arm. A cartridge pen is used for clear, low maintenance recording.
The chart scale may be in either millibars, inches of mercury, or millimeters of mercury. Charts are driven by a battery-operated clock with selectable rotation periods of 1 day, 7 days, or 31 days. Actual daily and weekly recording periods are 26 hours and 176 hours to prevent overwriting of the chart clip.
For outdoor installations, the barograph should be placed in an instrument shelter to shield it from rain, dust, and solar radiation. For best results, the barograph should be installed indoors.
This instrument has been discontinued by the manufacturer. Charts and pens are still available. Please contact us for information regarding repairs and replacement parts.