Characterisation of the Draw Resistance Across a Lit Cigarette

The consumer senses and reacts to the draw resistance of the cigarette after it is lit. In spite of this obvious fact, this physical parameter is usually measured under standard conditions on the unlit cigarette (1). In order to evaluate more accurately the smokers’ perception during the course of cigarette smoking, the theoretical aspects of the draw resistance measurement of a lit cigarette have been studied and an experimental device has been developed.

During puffing on a smoking machine, the variation of the pressure in the cigarette holder is influenced by several parameters which are independent of the characteristics of the cigarette itself, such as the airflow and the experimental device characteristics. Theory and experiments show that the saturation of the Cambridge filter pad and the dead volume, in the sample holder and connection tubes, significantly modify the measured pressure at the mouth end. The impact of these modifications can be minimized by the calculation of a single parameter which is characteristic of the draw resistance of the cigarette, and derived from the evolution of pressure over time. In addition, the integration of the measured pressure profile during each puff provides another way for the draw resistance assessment and gives a value related to the energy required to generate each of them.

An experimental device has been developed using a oneport smoking machine, a cigarette holder with a connection for a pressure sensor, an analog-to-digital converter and a recorder. For the calibration of the system, a procedure using multi-capillary pressure drop standards composed of capillary tubes is discussed.

Finally, the developed device and approach enabled the measurement and the recording of the draw resistance evolution over the time as the cigarette burns, and thus a better assessment of the potential smokers’ sensation during smoking.