The digital pressure gauge series DMN is intended especially for fixed mounting into places where direct displaying of the measured pressure is required. It will find use in the area of instrument construction and especially in places where it is necessary to monitor air overpressure in watched spaces because of safety and hygiene – eg. in operating theatres, etc. Its qualities especially come out compared with liquid column manometers (U-tubes) because it does not need practically any maintenance. The instrument is constructed for measuring pressure differences, measuring of relative overpressure or underpressure is realized by connecting only one pressure input. Then it is possible to operate this instrument as a digital barometer. In all cases, it is possible to measure only gas and non-aggressive media, humidity is not a problem.
The whole instrument, ie. the pressure sensor, feed, compensating and amplifying circuits and also the filter for increasing resistance against interference, are situated in a small plastic box from polycarbonate, which can be mounted on a panel or a DIN strip. The pressure inputs are realized by means of inlets from nickel coated brass with the diameter 5 mm, which are suitable for putting on a tube, or a quick coupler can be used for higher pressures. Besides that the medium comes into contact with silicon, silicon
rubber and the plastic material polyetherimid.
For connecting power supply, there is a sealed arrested miniature connector, type DIN 43650 – C with a cable outlet , size PG7, which enables using cable with the diameter max. 6.5 mm.
The pressure is scanned on this gauge by means of a sensor with a silicon membrane, the measuring principle is piezoelectric. Thanks to this, the sensor achieves high overload capacity, is resistant against vibrations and can operate in any position. The electronics is realized by means of surface mounting technology.
The digital data corresponds with the instantaneous pressure and is displayed on a 3.5-figure LCD display in kPa with differentiability 0.1% of the nominal range. A positive value corresponds with higher pressure on the positive pressure input. The instrument enables measuring pressure up to 200% of the nominal range. Measuring and renewal of the data on the display is made approximately 3 times a second.
The gauge calibration is fixed to the required range. Fine adjusting (ca. by 1%) of the end points of the transfer characteristic can be made by means of trimers which are accessible after unscrewing the sensor cover. The trimer for adjusting the range beginning (zero) is marked red. Short-circuit couplings for choosing the dumping time constant are also situated under the cover.
