Keller AG für Druckmesstechnik has introduced no less than five intrinsically safe electronic pressure gauges for use in areas subject to gas explosion risks. The type approvals are compliant with the ATEX Explosion Protection Directive regarding explosive gases. The electronic design of these devices is trimmed to minimise energy consumption, so it is also possible to replace the batteries inside areas with explosion risks.
The simplest version, model ECO 1 Ei, offers high resolution and reproducibility for both measuring ranges (-1…30 bar and 0…300 bar), together with accuracy (typical) of 0.5 %FS and an integrated min/max memory. The application range as per the ATEX directive is defined by identification markings Ex ia IIC T5 or T6. Keller’s type LEO 1 Ei and LEO 2 Ei electronic pressure gauges feature microprocessor-assisted compensation to ensure an extremely narrow total error band (including temperature errors) of only <0.2 %FS over the entire range of operating temperatures from 0 ... 50 °C. The zero point can be selected freely within the four measuring ranges between -1…3 bar and 0…700 bar. An automatic switch-off function guarantees energy efficiency. Both models feature sampling rates of 2 Hz and integrated min/max memories.
The special feature of the LEO 1 Ei is its additional memory for peak values. In peak mode (as it is known), even extremely short-lived peak values for system pressure are registered with a sampling rate of 5’000 Hz. These values are often critical for the lifetimes of hydraulic plants. For both these pressure gauges, the application range as per the ATEX directive is defined by identification markings Ex ia IIC T5 or T6.