Monday, January 23, 2012

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










2 comments:

  1. Hi,

    Calibration is a process when the output signal of the sensor is compared to the value measured by an accurate device, and the relationship between the measured and the accurate value is determined. The pressure transducer is connected to an air reservoir L, and the pressure in the reservoir is measured by a manometer filled with water. The pressure transducer is connected to the reservoir and has an electric current output. This way, the pressure measured by the manometer and the output current of the pressure transducer can be related. Thank you.

    Digital Manometer

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  2. Great post. Excellent presentation. Thanks.

    -Himmelstein.com

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