Cloud and Pour Points
In predicting these properties, it is not necessary to break down the product TBP as
we have done for specific gravity, sulfur, etc. The accuracy of the tests and of
blending indices does not warrant this. These properties are therefore read off
directly from the mid-boiling point of the whole product. Considering the gas oil
used in the previous example, its mid-boiling point is about 510
F, from the crude
assay its pour point is À5
F, and cloud point is +4
F. Determining pour point for a
blend of two or more products is rather more difficult. In this case blending indices
0
10
20
30
40
50
Vol % Distilled (TBP)
60 70
80
90
100
640
A Mid − Distillate TBP Curve
620
600
580
560
Comp 6
M BPT
591 °F
M BPT
550 °F
M BPT
520 °F
M BPT
460 °F
M BPT
400 °F
13%
Vol
18.5%
Vol
16.5%
Vol
410 °F
13% Vol
21.0% Vol
Comp 5
Comp 4
Comp 3
Comp 2
Comp/
M BPT
540
520
500 °F
480
460
440
420
400
380
360
340
Fig. 10 Typical pseudo component breakdown
26
D.S.J. Jones
In predicting these properties, it is not necessary to break down the product TBP as
we have done for specific gravity, sulfur, etc. The accuracy of the tests and of
blending indices does not warrant this. These properties are therefore read off
directly from the mid-boiling point of the whole product. Considering the gas oil
used in the previous example, its mid-boiling point is about 510
F, from the crude
assay its pour point is À5
F, and cloud point is +4
F. Determining pour point for a
blend of two or more products is rather more difficult. In this case blending indices
0
10
20
30
40
50
Vol % Distilled (TBP)
60 70
80
90
100
640
A Mid − Distillate TBP Curve
620
600
580
560
Comp 6
M BPT
591 °F
M BPT
550 °F
M BPT
520 °F
M BPT
460 °F
M BPT
400 °F
13%
Vol
18.5%
Vol
16.5%
Vol
410 °F
13% Vol
21.0% Vol
Comp 5
Comp 4
Comp 3
Comp 2
Comp/
M BPT
540
520
500 °F
480
460
440
420
400
380
360
340
Fig. 10 Typical pseudo component breakdown
26
D.S.J. Jones