LIGHTER LIFE, TEMPERATURE AND INITIAL CO YIELDS
Authors: Ian F. TINDALL*, Shabir MOGHAL*, Peter JORDAN*, Linda P. CRUMPLER**
*Cerulean Milton Keynes UK, **Cerulean, Richmond VA USA
Abstract
5
Coil lighters used to initiate smoke runs can be operated at different surface temperatures whether
deliberately or unwittingly. This surface temperature is shown to be related to the pre-light time and the
age of the lighter in terms of in use cycles and in use temperature. Lighter surface temperature decreases
with repeated use and this is accelerated as the initial surface temperature is increased. It is possible
to approximate the surface temperature of the lighter coil by reference to the number of lighting cycles
employed and the pre-light time. Using different lighter surface temperatures, achieved by altering the
pre-light time, it is shown that different initial CO yields are achieved when smoking monitor test pieces
under ISO conditions but that these differences are not statistically significant when smoking under a
Health Canada Intense (HCI) regime. It is concluded that by understanding this effect modifications can
be made to lighting temperature and this should be a consideration in maintaining consistent CO yields.
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2.5
2
1.5
1
ISO CO mg/cig 500°C light
ISO CO mg/cig 580°C light
HCI CO mg/cig 500°C light
HCI CO mg/cig 580°C light
Figure 4: CO yield for different initial lighting temperatures. Test conducted under ISO and HCI regimes
500
The initial lighting temperature has an impact on the CO yield from the first puffs (see table 2 and figure
4). There is a significant statistical difference between the two lighting temperatures deployed in this
experiment when ISO smoking is used but not when HCI smoking. It is postulated that the more intense
puffing of the HCI smoking masks the lighting temperature effect. A lower ignition temperature can have
a pronounced impact on first puff CO yield. A 3% change in CO yield can be obtained with a 20% drop in
lighter temperature.
400
300
200
100
0
Energised me (ligh
ng me) seconds
Initial lighter temperature
348°C
380°C
503°C
578°C
Decay per lighting cycle
0.02°C
0.18°C
0.32°C
1.34°C
Table 1: Decay rate per lighting cycle for initial lighter temperature conditions
Figure 2: Plot of lighter surface temperature with energised time.
ISO smoking
Change in Temperature per Cycle
600
HCI smoking
Pre-light time seconds
30
60
30
60
Mean CO yield first 2 puffs
2.41mg
4.01mg
2.48mg
4.01mg
Standard deviation CO yield first 2 puffs
0.150
0.210
0.100
0.220
Table 2: Means and standard deviations for different initial lighting conditions
550
y = -1.3432x + 578.81
CONCLUSION
500
Lighter temperature has an impact on the initial CO yield during smoking. Conventionally the hotter the
initial lighting temperatures the higher the CO yield appears counter intuitive. The more intense puffing of
the HCI regime masks this effect.
y = -0.3218x + 503.53
450
y = -0.1838x + 382.69
400
Applied lighter temperature can be changed by changes in the pre-light time, the time before application
and the lifetime of the lighter being used (number of lighting cycles). It would be possible to compensate
for ageing effects by adjusting the pre-light time. To restrict the CO yield change due to cooler lighting to
less than 1 per cent the pre-light time would need to be increased by 5 seconds every 40 lighting cycles.
350
y = -0.0225x + 348.13
Cycle Number
Figure 3: Rate of change of coil temperature due to cycling of lighters for different initial temperature
conditions
30
25
300
References
[1] Determination of “Tar”, Nicotine and Carbon Monoxide in Mainstream Tobacco Smoke, Health Canada Method T-115, 1999
[2] ISO 3308:2012 Routine analytical cigarette-smoking machine -- Definitions and standard conditions
[3] ISO 8454:2007 Cigarettes -- Determination of carbon monoxide in the vapour phase of cigarette smoke -- NDIR method
[4] Patskan, Reininghaus ”Toxicological evaluation of an electrically heated cigarette Part 1: overview of technical concepts and
summary of findings”J.Appl.Toxicol. 23 323-328 2003
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channel
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The effect of repeat lighting cycles is also clear, the surface temperature of the coils age. The rate of
aging is a function of the lighter initial surface temperature (see figure 3 and table 1). The rate of decay is
calculated on the basis of a linear regression, this is only an approximation as over extended cycling the
curve tends towards a second order decay.
CO yield mg/cig 2 puffs
600
0
The lighter temperature as a function of pre-light time is clear (figure 2), up to 60 seconds the lighter
temperature increases in a predictable manner. What is not normally appreciated is that during the delay
between pre-light ending and the lighter being applied the coil continues to rise in temperature. Delays in
lighting will inadvertently change the lighting characteristics of the cigarette under test.
3.5
0
Smoking experiments were conducted using CORESTA monitor CM7 test pieces using ISO and HCI
protocols [1,2,3 ]. CO analysis was conducted using a COA analyser fitted with a Luft cell and calibrated
with test gases traceable to national standards.
Results and Discussion
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0.5
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The coils from a linear smoking machine (Cerulean SM450) were used in the experimental procedures.
Surface temperature of the coils was measured using two different techniques, a K type thermocouple
situated 1mm from the hot surface (equivalent to the lighting position of the cigarette rod) and using a
thermal imaging camera (figure 1) calibrated against a black body radiation source.
700
15
Experimental
Average lighter temperature
10
It is common practice to replace lighter elements on a regular basis on manufacturer’s recommendation
but there is little evidence for what constitutes a reasonable lighter lifetime. A study designed to
examine the relationship between lighter temperature and CO and also what factors influence lighter
surface temperature would assist in making informed decisions concerning lighter exchange on routine
smoking machines.
Figure 1: Thermal camera visible spectrum image of coil test set-up and pseudo-colour image
of coil after 50 seconds pre-light. Maximum and point temperatures displayed
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There is a commonly held belief that the lighter temperature of smoking machines impacts the CO
yield of the first few puffs. Evidence in the literature to support or refute this assertion is elusive. There
have been a number of studies on heated tobacco products [e.g. 4] but these do not deal with the
combustion / pyrolysis actions of conventional machine smoking.
4.5
Temperature of coil surface °C
Introduction
Yield for 2 puffs for changing lighng condions