A barograph is a measuring instrument that records the temporal variation of air pressure on a paper-covered drum. The resulting curve is called a "barogram." Analyzing the barogram can provide the expert with clues about future weather developments.
Barographs are particularly common on ships. Barographs also play a role in aviation, particularly gliding. In these cases, however, they are often referred to as altimeters. Since air pressure decreases with altitude, the altitude profile of the flight can be analyzed after landing. There are also barographs that record the air pressure curve on a disc, or electronic barographs that display the barogram on an (LCD) display.
Aneroid barographs are used to continuously record atmospheric pressure. The measuring element is a set of seven diaphragm cells. It is made of a corrosion-resistant copper-beryllium alloy, which has proven itself for years to be an excellent choice for pressure measurement due to its excellent elastic properties. Aging, hysteresis, and elastic aftereffect are virtually nonexistent.
The temperature influence on the set of sensors and the transmission system is compensated by a bimetal element across the entire measuring range and within a temperature range of -30 to +40 °C. All axes of the precision mechanical measuring mechanism are mounted in stone, which means the instruments exhibit only minimal static friction.
The barographs are available with either a mechanical or quartz-controlled clockwork, which can be easily switched from weekly to daily or monthly cycles. The recording devices are supplied complete with fiber-tip pens and chart paper for a year's supply.
For use at sea, Fischer barographs are available with a vibration-damped measuring mechanism.
The main features of the barograph are:
- 7-fold membrane can set
- corrosion-resistant, elastic material
- good measurement accuracy (± 0.5 hPa)
- long-term stable
- temperature compensated
- switchable (1d - 7d) mechanical movement
- high reliability
- maintenance-free
