In our paper we present the results of a long-term emission measurement of volatile organic compounds emitted by a single-hull floating-roof tank. The tank has a capacity of 12,000 m(3) and is used to stock commercially available gasoline. Due to imperfect seals and the formation of lubricating films during withdrawal, subsequent emissions of volatile compounds have to be expected. Therefore, a non-zero probability has to be assumed for the formation of ignitable concentrations of flammable gases, resulting in according an explosive gas area classification. Here a representative single-hull floating-roof tank is monitored using an appropriate network of infrared (IR) detectors, accompanied with measurements using a high resolution photoionization detector (PID). Measured values have been compared to the expectations estimated applying the API 2517/2519 and the VDI 3479 standards. The aim is to record data for an explosive gas area classification based on actual emissions, potentially allowing for a regrading of zone 1 to zone 2 classified locations.