78b & 78bm
height in mm
for 1 hPa
Accuracy of reading / limits of Error
± 0.3 hPa
± 0.2 hPa
± 0.1 hPa
* If occasionally occurs extrema of pressure variation the customer can use the a device to select the suitable range of 66 hPa (mbar) within the total range of 146 hPa (mbar)
The aneroid barographs are precision instruments for continuos recording of atmospheric pressure. In comparison with the values of atmospheric pressure read on mercury barometers, those obtained by aneroids are independent of the resp. ambient temperature and gravitational acceleration so that the corrections customary with mercury barometers are not applicable. Thus, aneroid barographs are used everywhere, where there's quick determination of momentary atmospheric pressure of interest, in connection with observation and documentation of barometric pressure.
As measuring element serves a set of aneroid boxes of highly qualified material, which is free of aging and after-effects to an especially high extent. Alteration in length of this latter, depending upon barometric pressure is transmitted to the pen arm, via a lever mechanism, which, thus, records the course of atmospheric pressure in a steady curve on the paper strip, placed tightly around a vertically arranged drum. An over the whole range exact functioning temperature compensation is obtained by means of a bimetal strip intercalated in the transmitting system.
The pen rests against the chart with an always equal pressure, by the proper weight of the pen arm and may be lifted-off from without. By means of a device for time-marks that can be operated from outside, certain moments of time, as for instance, checking to schedule of indication, may be marked on the diagram, in that, by pressure upon a button, projecting from the lateral wall, the pen effects a short vertical stroke.
As mean atmospheric pressure decreases with increasing height, barographs must always be adjusted to the height of the place of mounting. There is the possibility to readjust and recalibrate the instrument for different heights above see-level at a calibration institute or at factory.
According to choice, time of rotation of the drum may be one week or one day. Generally, the recordings best to survey are those of one week's rotation. Against additional charge there can be supplied change gear wheels. The time of running of the driving mechanism is appr. 9 days in every case.
No. 78a Normal Barograph
This Barograph is the preferently used type in national and foreign weather stations and in other places of climatological interest. It registers atmospheric pressure at a height of recording of 0.75 mm for 1 hPa; the limits of error amount to ±0.3 hPa.
In standard execution the instrument is supplied in a metal casing, which has been provided with a very resistant grey hammertone finish. If the barographs named are to be installed in a representative locality, where the metal casing does not correspond to the frame of the equipment, they may be supplied with an all-around glazed rare-wood casing.
It is equipped with a high quality set of eight aneroid boxes as well as complete temperature compensation in the total pressure measuring range and usable at local heights from -50 to +5700 m, referring to sea level resp . usable between 445 and 1060 hPa.The instrument will be delivered adjusted from factory in a suitable measuring range.
Time of drum rotation: daily or weekly
Range: 105 hPa (mbar)
Ø 93.3 mm, height: 93 mm
time of running: app. 9 days
Recording height for 1 hPa: 0.75 mm
Recording height total: 79mm for 105 hPa
1 fiber pen
1 set of recording charts (100 charts for daily or weekly rotation)
No. 78b and 78bm Large Barograph
This barograph for precision-measurement, as compared to the normal barograph 78a, has the double scale of recording. A corresponding larger number of aneroid-boxes (12 pieces) guarantees measuring accuracy for recording height of 1.5 mm for 1 hPa; the limits of error amount to ±0.2 hPa.
Because of its increased accuracy of reading this instrument has found large introduction in flying, as well as in many meteorological stations. It is used with preference everywhere there, where the more accurate determination of atmospheric pressure and the tendency of the course of atmospheric pressure is of importance.
Time of drum rotation : daily or weekly
Range: each 105 hPa (mbar)
Record ing drum:
Ø 133 mm, height: 174 mm
Recording height for 1 hPa: 1.5 mm
Recording height total: 160mm
time of running: app. 9 days
1 fiber pen
1 set of recording charts
(100 charts for daily or weekly rotation)
The instrument is usable at local heights from -50 to +2700 m, referring to sea leve resp. usable between 685 and 1060 hPa.The instrument will be delivered adjusted from factory in a suitable measuring range.
If the barographs named are to be installed in a representative locality, where the metal casing does not correspond to the frame of the equipment, they may be supplied with an all-around glazed rare-wood casing. (model 78b)
No. 78m Microbarograph
The Microbarograph 78m is a highly sensitive measuring instrument for especially sensible and precise recording of atmospheric pressure. Owing to the great height of pen travel of 3.8 mm, for every hPa (mbar) of alteration in pressure, also slightest variations of pressure and fine structurees are well to be made out and read with a accuracy of ± 0.1 hPa (mbar).
As model 78m the measuring system is mounted on a solid light-metal socle, on which the glazed protective fine wood casing is resting. The microbarograph model 78mm has a metal housing.
The set of aneroid cells consists of fifteen single cells which, to a high degree, are free from ageing and hysteresis, because best-suited materials are chosen, only, and owing to a special thermic treatment. Frictional resistances of the transmitting system has been reduced to a minimum by most careful manufacture of the bearing beds and by arranging the aneroid cells ina hanging kind of way. A small vibrator generates a slight, hardly sensible vibration of the housing and the measuring system, which contributes to a further reduction in bearing friction, and to an increase in accuracy and sensibility of pen adjustment.
The aneroid cells are protected against dust and damage by a metal tube.
The Microbarograph 78m is supplied in 12 types for different site of installation between -1200 and +4600 meters. Seven ranges of 66 hPa each one displaced from the following by 13.3 hPa, may be covered without new calibration, so that the total range comprices 146 hPa. The adjustment of the seven ranges for the place of installation is effected in a way, which is as quick and easy, as it is sensitive, by turning the setting screw arranged above the set of aneroid cells which is equipped with a correspondingly numbered, divisioned disc arrangement. If occasionally occurs extrema of pressure variation the customer can use the above described device to select the suitable range of 66 hPa (mbar) within the total range of 146 hPa (mbar).
sealevel in m
Time of drum rotation: 1 week or 1 day
reversible by exchange of gear wheel (optionaly)
Range: 66 hPa (mbar), adjustable within 146 hPa (mbar)
Ø 133 mm, height 259 mm
height of recording: 247.5 mm (1.33 hPa (mbar) = 5 mm)
time of running: app. 9 days
Chart size: 261 x 428 mm (h x w)
1 set of charts (100 charts for daily or weekly rotation)
1 spare metal pen and 1 bottle of special ink
or alternative 1 fiber pen
1 power supply for vibrator
When ordering, please indicate altitude of site of installation and selected drum rotation
Dr. Alfred Müller - Meteorologische Instrumente KG
Chausseestraße 39 / 42c, D-15712 Königs Wusterhausen
Telefon: +49 (0)3375 9025-32 Telefax.: +49 (0)3375 9025-36