Pressure Transducer Calibration

After constructing the 12V power supply, I calibrated the output voltage from the transducers against simulated input pressures. Six resistors were used. The following table summarizes the results:

Calibration Resistance(Kohm)    Pressure(psi)    Transducer1(mV)    Transducer2(mV)

33                                                   1694.92               28.60                         28.26

39                                                   1434.62               24.94                         25.65

56                                                     999.80               17.13                         17.89

68                                                     823.67               13.80                         14.62

100                                                   560.51                 9.15                           9.89

180                                                   311.75                 4.66                           5.50

The following equation summarizes the relationship between resistance and pressure as given by the pressure transducer information sheet.

P=5558.781 * R^(-.99808393)

Here are the calibration curves that will be used to convert  the output voltages from the setup into internal pressures of the feed system and combustion chamber.

Pressure 1 = 54.989675 + 55.330104*P1 Voltage

Pressure 2 = 8.0671329 + 55.608625*P2 Voltage

The last data point at 33Kohm was removed from both plots since it was a considerable outlier from the trend produced by the other data points. It is acceptable to remove this point since it corresponds to a pressure well above the operating range of the motor or oxidizer feed system. 

Here is a picture of the calibration setup:

Setup