The volume rate of the gas mixture of the burner tip. It depends on operating conditions such as gas pressure; the ambient temperature and pressure should also be stated.
Source:
PAC, 1986, 58, 1737. 'Quantities and units in clinical chemistry: Nebulizer and flame properties in flame emission and absorption spectrometry (Recommendations 1986)' on page 1742 (https://doi.org/10.1351/pac198658121737)