DIFFERENTIAL PRESSURE SENSING QUARTZ CRYSTAL RESONATOR BLOCK BRKM-P APPLICATIONS BRKM-P is a quartz crystal resonator assembly, which consists of a measuring and a reference quartz crystal, both packaged in a rectangular enclosure. The resonance frequency varies with pressure-induced stress. BRKM-P is designed as a component for precision electronic differential pressure transducers, manometers and controllers with a frequency output for conversion of absolute pressure or differential pressure to frequency. FEATURES - High resolution and accuracy Long term quartz crystal stability Wide temperature range (-55…+80 °C) Low power consumption Suitable for precision pressure equipment In gauges of differential pressure BRKM-P is used to convert a pressure difference to a differential frequency output signal fout =fMEASURING – fREFERENCE. An absolute pressure ( or differential pressure) P1 is applied to diaphragm (1), while the absolute atmospheric pressure (basic pressure) Р2 acts on diaphragm (3) (see drawing below), which stresses the reference resonator through the metal pipe (6). One end of the connecting pipe is attached to an outlet of the quartz block, and the second one to an internal cavity of the case of the gauge (5) where BRKM-P is subjected to the pressure Р1. The internal cavity of the gauge is usually filled up by oil. ELECTRICAL CHARACTERISTICS (at normal climatic conditions) / OPERATING CONDITIONS PARAMETERS SPECIFICATIONS AND REMARKS UNITS Electrical characteristics Frequency Range, fO Resonance Resistance typ./max., Rr Drive Level max., DL Insulation Resistance min. 32.000…48.000 200 / 250 3.0 400 kHz kΩ µW MΩ Motional characteristics f(P)=fO +A1*P +A2*P2+ A3*P3 where: f(P) – crystal frequency at pressure P (Hz), fO – crystal’s frequency(in Hz) at zero value of pressure P, A1 – Linear coefficient = Sensitivity A2, A3 – Second and the third order coefficients*. Nonlinearity less than 0.4% FS. Operation conditions Model Pressure Range UNIT Sensitivity (Linear Coefficient A1) measuring crystal reference crystal 7959 ± 5…20%FS 3367 ± 5…20%FS 1235 ± 5…20%FS 304 ± 5…20%FS 127 ± 5…20%FS Overall Dimensions / Weight Hz/MPa 25 x 23 x 4.5 / 6.0 Hz/MPa 25 x 23 x 5.1 / 7.0 Hz/MPa 25 x 23 x 7.0 / 9.5 Hz/MPa 25 x 23 x 10.4 / 17.0 Hz/MPa 25 x 23 x 12.2 / 18.5 0.1…25.0 79.98…106.64 UNIT BRKM-0.16 0 – 0.16 MPa BRKM-0.5 0 – 0.50 MPa BRKM-1.5 0 – 1.50 MPa BRKM-6.0 0 – 6.00 MPa BRKM-16.0 0 – 16.00 MPa Pressure Range, P Pressure range of Reference Crystal Variation of frequency difference over any 10K within the operating < 0.1 temperature range Operating temperature range, TOPR (typ/max) -55…+80 / -40…+100; -269…+250** Storage temperature, TSTR +5…+40 Maximum deviation over temperature 0.75 Relative deviation of linear coefficient A1 from its average value ± 5…± 20 Aging first year/next years max. ± 5 / ± 25 FS Pressure Hysteresis < 0.02 Reproducibility of temperature dependence of crystal frequency 0.05 fT=fO+B1*T+B2*T2 Vibration Resistance, ∆f/f0 5g / 50-2000 Hz, 8 hours / ±7 ppm max. *A1, A2 and A3 coefficients are specified on request. **Temperature range can be increased from -269 to +250 °C on request. Temperature sensing quartz crystal RKT206 is used for compensation of a temperature deviation of BRKM-P. PACKAGE DIMENSIONS +0.50 23.00 0.00 P2 UNITS: millimeters +0.50 25.00 0.00 1 – bottom diaphragm 6 2 - gasket 5 3 – upper diaphragm 4 4 – cover 3 2 1 5 – gauge internal cavity 6 – connecting pipe 7 – contact leads 7 P1 GmbH & Co. KG Wasemweg 5 D-74821 Mosbach Germany page 1(1) www.AXTAL.com fon: +49 (6261) 939834 fax: +49 (6261) 939836 E-mail: [email protected] UNIT mm / g mm / g mm / g mm / g mm / g MPa kPa % °C °C % % ppm % % ppm