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Guideline – Automatic Overfill Prevention Systems for Terminal Loading Racks v2 Page 22 of 23
Pipe length
(metres)
Pipe diameter (inches)
3
4
6
8
10
12
14
Volume (litres)
10 45.604 81.073 182.41 324.29 506.71 729.66 993.15
20 91.207 162.15 364.83 648.59 1013.4 1459.3 1986.3
30 136.81 243.22 547.24 972.88 1520.1
2189 2979.4
50 228.02 405.37 912.07 1621.5 2533.5 3648.3 4965.7
Table 1 – Liquid volume of pipe work (litres)
The total amount of gasoline that will flow into the road tanker, for the various detection
routes, will be the area under the graph in figure 2, which will be unique for each loading
arrangement. Whether the road tanker becomes overfilled, or gasoline is lost from
containment depends on how much empty volume there is in the tanker compartment
when the control of flow is lost, and whether gasoline flows into other unfilled
compartments and the vapour recovery system. Experience has shown that whilst
gasoline from an overfilled compartment does flow into other unfilled compartments, and
into the vapour recovery line, it preferentially flows out of containment. Consequently,
when estimating whether a configuration will be able to prevent a loss of containment, no
claim should be made that gasoline can flow into other compartments or the vapour
recovery system.
The
time
between
the
high
level
detection
in
a
tanker
compartment and overflow occurring depends on the size of the compartment, and the
flow rate. Table 2 shows example times based on a range of flow rates and compartment
sizes.
Flow rate
after failure
(litres/min)
Compartment size (litres)
7600 7000 6000 5000 4000 3000 2500
Approximate remaining volume in compartment at
high level detection point (litres) @ 95% full
380
350
300
250
200
150 150*
Time to loss of containment after high level detection
(seconds)
2500
9.1
8.4
7.2
6.0
4.8
3.6
3.6
2200 10.4
9.5
8.2
6.8
5.5
4.1
4.1
1900 12.0 11.1
9.5
7.9
6.3
4.7
4.7
1700 13.4 12.4 10.6
8.8
7.1
5.3
5.3
1500 15.2 14.0 12.0 10.0
8.0
6.0
6.0
1200 19.0 17.5 15.0 12.5 10.0
7.5
7.5
1000 22.8 21.0 18.0 15.0 12.0
9.0
9.0
800 28.5 26.3 22.5 18.8 15.0 11.3 11.3
500 45.6 42.0 36.0 30.0 24.0 18.0 18.0
300 76.0 70.0 60.0 50.0 40.0 30.0 30.0
Table 2 – Time before overflow of a tanker compartment