SonTek/YSI Argonaut-XR Technical Manual - HydroScientific West
SonTek/YSI Argonaut-XR Technical Manual - HydroScientific West
SonTek/YSI Argonaut-XR Technical Manual - HydroScientific West
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<strong>SonTek</strong>/<strong>YSI</strong><br />
3. Frequency External Pressure Sensors<br />
3.1. The Druck RPT (DRUCK)<br />
Although the PAROS provides the required accuracy, its size and external location cause additional<br />
complications when mounting and deploying a system. <strong>SonTek</strong>, in collaboration with<br />
Druck, Inc., now offers the Druck RPT (resonant pressure transducer) sensor. This sensor is very<br />
compact and fits inside the same mounting socket as the regular strain gage (Figure 1). The<br />
DRUCK sensors are available for ADP, PC-ADP, <strong>Argonaut</strong> SL/<strong>XR</strong>, and Hydra systems. The differences,<br />
when compared with a strain-gage sensor, are as follows:<br />
2<br />
• The DRUCK is an absolute sensor. It reads 1 dbar in air; a strain gage reports 0 dbars in air.<br />
• Requires a special interface to sample the frequency signal.<br />
• Sampling rate is limited to 10 Hz (ADVs and Hydras) because of the time required to sample<br />
the frequency signal with sufficient precision.<br />
• Requires calibration matrix (specific to each sensor) to be loaded into the processor (system<br />
CPU or a user PC) to obtain valid pressure readings.<br />
• Available in 50-psia pressure rating only (equivalent to ≈22 dbar strain gage).<br />
3.1.1. Sensor Calibration Template<br />
Each current meter purchased from <strong>SonTek</strong> that has the DRUCK sensor installed already has the<br />
appropriate calibration coefficients loaded into the processor. If this information is lost, you can<br />
use the calibration sheet provided by the pressure sensor vendor to construct your own calibration<br />
file. The structure of the DRUCK calibration file, required by <strong>SonTek</strong> systems, is as follows.<br />
• Pressure Sensor Serial Number<br />
• Oscillator Frequency (in Hz)<br />
• X<br />
• Y<br />
• Low end of temperature range<br />
• Corresponding voltage of the diode<br />
• Diode sensitivity<br />
• K00 K01 K02 K03<br />
• K10 K11 K12 K13<br />
• K20 K21 K22 K23<br />
• K30 K31 K32 K33<br />
• K40 K41 K42 K43<br />
• K50 K51 K52 K53<br />
Example – Druck calibration file 1145118.drk:<br />
Note: The X, Y, and K coefficients can<br />
be found on the Druck calibration sheet.<br />
1145118<br />
12.0000000E+06<br />
+8.8880000E+03<br />
+5.5200000E+02<br />
-10<br />
622<br />
-2.21<br />
+1.6214761E+03 -2.0699499E-02 +5.5220000E-05 -5.6160001E-08<br />
+1.8251241E+00 -5.8612000E-06 +3.6197001E-08 -3.8715001E-10<br />
+3.8615943E-04 -1.5274000E-09 -4.7059999E-12 -1.3233001E-13<br />
+7.0553313E-08 -1.9064000E-12 -4.0058001E-14 +9.0119996E-16<br />
+1.7913088E-11 -1.3525000E-15 +1.7647000E-17 +3.8552999E-19<br />
+3.7756621E-15 +1.9573000E-19 +3.6951001E-20 -3.3300999E-22<br />
Using Frequency Pressure Sensors with <strong>SonTek</strong>/<strong>YSI</strong> Systems (June 2001)