The self-stablized set of five aneroid capsules used in this precision instrument are made of a corrosion proof copper-beryllium-alloy. This alloy has been well established for measuring the atmospheric pressure for many years because of its remarkable elastic properties. The aneroid capsules are nearly free of age-hardening, hysteresis, and elastic after-effects.
The influence of temperature on the set of aneroid capsules and the transmission system is compensated by a bimetal arm over the whole measuring range and for temperatures between -30 to +40 °C (-22 to 104 °F). The motion of the aneroid capsule is transmitted to the axle of the pointer by driving a segment and wheel with an excellent fine finish gearing. All bearings also have an excellent fine finish. The instruments have only a bare minimum of idle friction because of the advantageous shape of the levers and bearings. The double needle design removes parallax error in reading.
The new dials showing both millibars (mb) and inches of mercury have been custom made for American and British users on land and sea. The mb (same as hectoPascals) dial is the international standard for maritime applications.
A certificate of accuracy (view sample) is provided with each instrument. Each has a unique serial number on a metal plate on the top of the instrument.
||better than or equal ± 0.7 mb (± 0.02 inHg)
||0.5 mb and 0.05 inHg
||mb and inches of mercury
||890 to 1050 mb = 26.30" to 31.00"
||flat white finish
For use at elevations below 2,600 ft. A high elevation model for 2,600 to 6,500 ft is available on request.