Testing a BP-20 pressure sensor

Tools Required:

• 7 V DC to 35 V DC source (12 V nominal, battery recommended)
• Digital Voltmeter (DVM) set to 20 V DC scale

Instructions:

• Disconnect BP-20 from logger
• Connect DC supply (-) to black wire
• Connect DC supply (+) to red wire
• Set DVM to 20 V DC scale
• Connect DVM (-) to black wire
• Connect DVM (+) to white wire (Note: older units have a both a green wire and white wire.  In this case, use the green wire.)

Measure and record output voltage on white wire (typically near 4 Volts)...

To determine the absolute pressure as reported by the BP-20 use the following:
                                         kPa = (21.79 x Vout) + 10.55
 
Performance Comparison:

• Check this value against the logger display to confirm scale is correct.
• Check this value against another barometer to confirm reading is correct.

Note: BP-20 should draw about 8 mA of current

Example:

BP-20 voltage output is measured to be 4.123 V DC...
kPa = (21.79 X 4.123) + 10.55
kPa = 100.4