Calibration of pressure transducers for small pressure differences

Two simple methods for the calibration of pressure transducers in the range 0 to 10 Pa are compared. One relies on water displaced, by known weights and the other uses helium in an inverted U-tube. The slopes of the calibration curves determined with the two methods agreed to better than 0.25% while the standard deviation of a typical calibration curve was better than 0.005 Pa.