728 CHAPTER 16
Table 16.16. Reference fuel blends
Standard smoke point Toluene 2,2,4-Methyl
at 101.3 kPa mm % (v/v) pentane % (v/v)
14.7 40 60
20.2 25 75
22.7 20 80
25.8 15 85
30.2 10 90
35.4 5 95
42.8 0 100
The smoke point of the blends are determined in the same way as the test procedure
given below. From the calibrating readings the correction factor f is determined from
the equation:
f =
(A
s
/A
d
) + (B
s
/B
d
)
2
where
A
s
=the standard smoke point of the first reference fuel blend
A
d
=the actual smoke point determined for the first fuel blend
B
s
=the standard smoke point of the second reference fuel blend
B
d
=the actual smoke point of determined for the second fuel blend
The test procedure is as follows:
Figures 16.8 and 16.9 are shown below for detailed reference:
1.0 Soak a piece of extracted and dried wick about 125 mm in length in the test
sample, and place it in the wick tube of the candle. Carefully ease out any twists
arising from this operation.
2.0 Introduce about 20 ml of the test sample into the clean dry candle place the wick
tube into the candle and screw and secure. Then insert the candle into the lamp.
3.0 Light the candle and adjust the wick so that the flame is approximately 10 mm
high. Allow the lamp to burn for 5 min. Raise the candle until a smoky tail
appears, then lower the candle slowly until the following stages occur:
r
First stage: An elongated pointed as sown as Flame A in Figure 16.10
r
Second stage: The pointed tip just disappears, leaving a slightly blunted flame
shown as Flame B in Figure 16.10
r
Third stage: A well rounded flame tip as shown in Flame C in Figure 16.10
The correct flame profile is Flame B. Determine the height of this flame and
record to the nearest 5 mm.
4.0 Make three separate observations using the same Flame sequence as given in item
3.0 above. If these values vary by more than 1.0 mm repeat the test with a fresh
sample.