Higher yield product smoking, are there yield errors inherent when using a mechanical smoking machine?

Transcription

1 Higher yield product smoking, are there yield errors inherent when using a mechanical smoking machine? Authors Tim Mason: Cerulean, Rockingham drive, Linford wood East, Milton Keynes, United Kingdom. Ian Tindall: Cerulean, Rockingham drive, Linford wood East, Milton Keynes, United Kingdom. Abstract Cigars when smoked using CRM#64/65 commonly give greater yields than cigarettes smoked under the corresponding ISO regime. Analytical cigar smoking is characterised by larger puff counts and an overall longer smoking time than the cigarette equivalent. It has been posited that pulling air and vapour phase through the Cambridge filter pad as it becomes increasingly loaded can result in reduced trapping efficiencies of the pad and so reduce the apparent yield of the product under test. An examination of breakthrough was made for different yield products using two Cambridge filter pads in series. The influence of pad area on trapping efficiency and retention was further examined using the same system and the reduction in vapour loss through use of a small diameter pad, relative to the larger pad, plotted against nominal yield. The effect of puffing (clearing puffs) on a pre-loaded Cambridge filter pad was examined for different loadings, different puff volumes and different pad diameters. A recommendation for modification of the method used when smoking cigars is presented with an estimate of the apparent impact this will have on measured TPM. The consequences and applicability of these changes for Canadian method intense smoking are explored. Introduction As the Health Canada method comes to the fore with high puffs and vent blocking the TPM yield to be collected by CFH s will be higher. Cigar smoking, especially long filler cigars, also creates considerable quantities of TPM. Together with the ambiguity surrounding clearing puffs in ISO 8454:2007 there may be some reason to ask if all the TPM is being captured. This study seeks to examine the suitability of different pad sizes used in routine cigarette and cigar smoking and the influence of multiple clearing puffs on pad yields. 1 P a g e

2 Experimental A linear smoking machine (Cerulean SM450) was used for the study. Puff volume and intervals could be adjusted and vent blocking holders were used for intense studies. Rods and pads were conditioned for 48hours in 60%RH, 22 C. For cigarette studies CM6 were used and for cigars a small commercially available cigar type was used. The machine could be fitted with either 44mm or 55mm CFH pad holders and a secondary CFH filter pad could be situated between the standard CFH and the puff engine. Table 1: Experimental regimes Experiment Product Regime Pad Clearing puffs Second pad 1 CM6 ISO 44 0 No 2 CM6 Canadian 44 0 Yes 3 Cigar ISO 44 0 Yes 4 Cigar Canadian 44 0 Yes 5 CM6 ISO 55 0 No 6 CM6 Canadian 55 0 Yes Results In each case the TPM measured has been compared with a calculated figure for TPM based on the normal smoking conditions. Figure 1: Per cigarette yields for ISO smoked CM6 onto a 44 mm and 55mm pads significant drop off is not apparent even at high TPM loads. 2 P a g e

3 Figure 2: Front and reverse of 44mm pads loaded with approximately 194mg TPM. There is no obvious sign of pad damage or breakthrough. Figure 3: Per cigarette yields for ISO smoked small cigar onto a 55 mm pad showing initial steady accumulation and subsequent drop off after 4 cigars (260mg TPM load). 3 P a g e

4 Figure 4: Secondary filter loading for small cigars. The filter behind the cigar shows that the lost TPM is not entirely as condensate as there is not an increase in weight per cigar smoked as more are smoked. Also the magnitude of vapour captured by this secondary filter is such that this does not account for the reduction in TPM observed at the first filter. Intense smoking magnifies these effects, in each case the reduction in yield being between 150mg and 300mg loading for CM6 and cigars respectively. Discussion It is apparent that as a CFH pad becomes loaded that there is a tipping point reached that results in a loss in yield. This is probably not in the form of condensate evaporating and then re-condensing see figure 4. It is also apparent that there is a maximum loading that creates this effect and that this is dependent upon pad size, larger pads being more capable of sustaining higher levels of TPM. For intense smoking of high yield products such as 100 s or 120 s three cigarettes smoked onto an individual 44mm pad could become close to overloading the pad. However, it is not evident from examination that pads have become overloaded see figure 2 4 P a g e

5 Figure 5: Effect of clearing puffs on a 44mm pad with TPM from 5 CM6 cigarettes smoked intensively. There is a decrease in TPM implying that there is a loss in a volatile or semi volatile component of the captured TPM as more air is drawn through the pad either as a clearing puff or through smoking. It is of note that the loss in weight per clearing puff is an order of magnitude greater than the increase in weight of the secondary filter per cigarette. The apparent yield of tobacco products can be reduced as the filter pad loading reaches or exceeds its capacity limit. Where TPM loads are high such as under intense smoking conditions or cigar smoking modifications must be made to the method. Currently the intense method for allows for a reduction in the number of rods smoked per pad. For cigarette smoking it is acceptable to reduce the number of cigarettes per pad. Cigar smoking methods (CORESTA Recommended Methods 64 to 68) also allow this but the method is not clear as to what should be done when the limit may be exceeded by a single high yield product. In theory it should be possible to create a thin-walled trap enabling a filter pad diameter of 60mm to be used. For cigarette smoking there would be an increase in surface area (and therefore anticipated TPM capacity) of 56% for a 55mm diameter and 86% for 60mm diameter device. This could perhaps even be increased to 65mm on a linear machine if alternate channels are omitted (normal channel spacing is slightly less than 65mm) For cigar smoking an increase from 55mm to 65 mm diameter would give an expected increase of 39%. The influence of clearing puffs is quite marked and could be a source of variability in yield determination. Moreover each puff through a pad will both deposit TPM but also remove a small portion of the TPM already on the pad. The more puffs through a pad the greater will be the loss through this desorption process. Knowing the composition of the lost TPM would be a key step to further understanding one source of variability in yields between different smoke experiments. 5 P a g e

6 Further experiments using solvent traps may be able to confirm the composition and quantities of volatile and semi-volatile components (not trapped by the glass fibre secondary filter) that make their way past the primary CFH. Conclusions It has been confirmed that yield errors can occur on mechanical smoking machines when yields are high due to the intensity of the smoking method (Health Canada Intense) or due to the product itself (large cigars). However it is likely that the bulk of any error is due to limitations in the trapping method employed rather than the design of the smoking machine itself. It is likely that the errors can be significantly reduced by way of changes to the smoking methods which permit the use of larger traps with a higher total TPM capacity. 6 P a g e