Validation of spirometer calibration syringes.

The volume calibration syringe is probably the single most important instrument in pulmonary function laboratories, yet no validation results have been published. In this study a sample of volume calibration syringes was validated. We weighed a 1-L and two 3-L calibration syringes before and after emptying them of water and determined the corresponding volume of gas by using a modified rolling seal spirometer. In this way we established an unbroken calibration chain between a certified weight of water and the corresponding volume of gas. The volume of a spirometer calibration syringe could be verified with an accuracy of ± 15 ml. The modified rolling seal spirometer had an accuracy of ± 11 ml at a volume of 1 L and ± 13 ml at a volume of 3 L. A sample of spirometer calibration syringes was validated and all syringes except for two small 1-liter syringes all had volumes within the label claimed volume ± 0.5%. Spirometer calibration syringes have a stable stroke volume even after many years of use and storage but have to be calibrated yearly to comply with international standard.