Super Systems 1500 VRSD - Manual (Page 8)

Model 1500 VRSD Operations Manual
Super Systems Inc. Page 8 of 28
5.0 Allow the sensor to reach equilibrium with the calibration salt.
5.1 With the power to the unit still turned off, leave the sensor in the
calibration salt for a minimum of eighteen (18) hours. It is acceptable to leave
the sensor in the salt solution for a longer period of time, even a few days, if
desired.
6.0 Begin the 75.3% (Span) calibration process.
6.1 After leaving the sensor in the salt for at least eighteen (18) hours, turn the
unit on. The reading on the display is not important at this point.
6.2 Simultaneously press the “75.3%” and “Calibration” buttons on the
microprocessor board.
7.0 Verify the 75.3% (Span) calibration.
7.1 Leave the sensor in the 75.3%RH calibration salt.
7.2 Record the temperature and the dew point of the sensor. Since there is no
display on the instrument, you will need to measure the voltage from the
microprocessor board and translate that into the appropriate measurement.
7.2.1 To determine the sensor temperature, measure the DC voltage
between pins 5(+) and 9(-) on the microprocessor board. The
voltage will be between 0 and 1VDC. Use the chart in Appendix C to
determine the temperature in °F, or use Appendix D to determine
the temperature in °C.
7.2.2 Temporarily record the sensor temperature.
7.3 Look up this temperature in Appendix “A” (Determining the Dew Point in
°F) or Appendix “B” (Determining the Dew Point in °C). Appendix A will show
the temperature values in Fahrenheit, and Appendix B will show the
temperature values in Celsius.
7.4 Next to the appropriate sensor temperature, note the number in the
corresponding column titled “75.3%”. This will match the measured dew
point, which can be verified wherever the dew point is displayed.
8.0 Determine the acceptability of the reading.
8.1 The value printed on the chart in Appendix A is a theoretical value, and
some variation can be expected. When a calibration is performed at SSi, we
certify (in writing) that the unit displays within +/- 1 degree of the theoretical