Application Note...

PCS400 Pressure Calibration System

Application:

Calibration of pressure transducers in an automotive engine test cell.

Challenge:

To provide a high accuracy, pressure calibration system that could be moved to any test cell in the factory.

Solution:

A portable test console was designed by this automobile manufacturer to address the requirement. A low profile console was chosen so that the top surface of the console could be used as a working surface for writing or placing documents on. The system also had the requirement of measuring specific temperatures in the test cells, so a digital thermometer was installed in the console. A Mensor PCS400 Pressure Calibration System ( Model 400-08) was selected as the "heart" of the transducer calibration system. The pressure range of the PCS400 was 1,000 psig with an internal Barometric Reference Transducer. The high accuracy version (0.01% FS) was necessary to optimize the calibration ratio between the calibration system and the transducers to be calibrated. The full scale pressure ranges varied from a low of 15 psi to 200 psig on the high end. The internal Barometric Reference allowed for the calibration of all the absolute pressure transducers in the test cell. In order to make this a turnkey system, all the other necessary pneumatic components were built into the console, including the vacuum pump, fittings, tubing, filters, etc. Metal tubing was utilized in order to minimize leaks and provide for long term durability. High quality pneumatic components were used to insure high performance and reliability of the system. The calibration software was written by the automobile manufacturer to communicate over the parallel port (GPIB) of the PCS400. Standardized calibration charts were designed to format the calibration data. The "cal chart" included the following key data: (a) actual pressure, (b) observed response, (c) calculated pressure, (d) difference between actual and observed, (d) percent difference and (e) standard deviation. The cal chart consists of 11 pressure points upscale including zero and 10 points downscale. The cal data is stored for future reference to the history of each individual transducer in each test cell. A Mensor Precision Barometer was also purchased to monitor the local barometric pressure for all the engine test cells.