With the mouthpiece and filter attached directly to the flow head, some users have reported unacceptable drift in their volume calculations. This can happen for the following reasons:
- By not using clean bore tubing.
- ADInstruments recommends using clean bore tubing to alleviate non-laminar flow across the mesh that may occur from this configuration.
- Temperature drift
- Make sure the Spirometer Pod / Amp is turned on so the internal circuitry is allowed to warm-up prior to starting the experiment.
- Do not place the Spirometer on the PowerLab or other electronic equipment as this may cause the Spirometer to heat resulting in temperature drift.