Transcript GT15USTsemDavidAu

Fuel Contamination
• Gasoline into diesel fuel
– Problems
• Lower diesel flashpoint - fire hazard
• Poor operability for diesel engines, lower cetane
number
• Engine damage
– Long term corrosion problem for the diesel
underground storage tanks
Outline
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What is a Diesel Flashpoint?
Flammable vs. Combustible Hydrocarbons
Diesel Flashpoint affected by Gasoline
Testing data at retailers from State Oil
Laboratory
– Substantial increase in failure in FY2015
– Summer vs Non-Summer season (vapor Pressure)
• Flashpoint of Diesel from Terminals
• Possible root causes
What is a Flashpoint?
• The flashpoint of a volatile material is the lowest
temperature at which it can vaporize to form an
ignitable mixture in air.
• When the ignition source is removed, the vapor may
cease to burn.
• Too low of a flashpoint is a fire hazard because
ignition may continue and lead to explosion.
• ASTM D975 Diesel Specification: 125 °F minimum
U.S. Definition of Flammable Liquid
• Class IA flammable liquids have a flashpoint
below 73 °F (22.8 °C) (the upper end of the
common range of room temperature) and a
boiling point below 100 °F
• Class IB flammable liquids have a flash point
below 73 °F (22.8 °C) and a boiling point
greater than or equal to 100 °F (37.8 °C)
• Class IC flammable liquids have a flash point
greater than or equal to 73 °F (22.8 °C) and
below 100 °F (37.8 °C)
Combustible Liquids
• Class II combustible liquids have a flash point
greater than or equal to 100 °F (37.8 °C) and
below 140 °F (60 °C)
• Class IIIA combustible liquids have a flash
point greater than or equal to 140 °F (60 °C)
and below 200 °F (93.3 °C)
• Class IIIB combustible liquids have a flash
point greater than or equal to 200 °F (93.3 °C)
Problems with Low Flashpoint
Diesel (gasoline contamination)
• Safety Hazard
• Lower Cetane Number
• Increases the Auto-ignition temperature
– vaporizes more fuel prior to ignition; rapid
pressure changes; engine noise and knocks
• Lower Lubricity
• Burns Hotter
• Gasoline: low flashpoint, high auto-ignition
temp
• Diesel: high flashpoint, low auto-ignition
temp.
• Mixed with ethanol blended gasoline
– Increase diesel auto-ignition temp.
– Ethanol + water + biodiesel* = perfect recipe for
bacteria growth and corrosion
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* most diesel fuel contains up to 5% biodiesel
All terminals are OK. Samples from
Terminal 6 is not from the Pipeline
All OK, except the one from the tanker truck
Flashpoint Test Methods
• Tifton Lab
– ASTM D93 Penske
Martens Close Cup
– 50 mil sample
– ASTM official
method
• Mobile Fuel Lab
– ASTM D6450 Mini-flash
Grabner (Continuous
Close Cup)
– 1-2 mil in an enclosed
environment
– No open flame, safe, no
waste disposal
Possible Root Causes
• Diesel flashpoint failure is almost non-existent
at the terminal level
• Switch Loading – residual gasoline from
previous load
• Split Loading – share common drains and
venting system
• Sharing common venting system for under
ground fuel tanks
• Human error – mis-filling
Conclusion
• Gasoline contaminated diesel is the major problem
for the local retailers at this time – more than water
related.
• Affects more than 220 retail stations in FY2015
• 1% gasoline can reduce the diesel flashpoint by 30 °F
• Winter season has more problem due to high vapor
pressure of gasoline
• Diesel flashpoint failure at terminals is almost nonexistent
• Switch loading probably the source of problems
Ethanol in Diesel Fuel
• Form bacteria in the presence of water:
– water and ethanol phase creates a perfect environment for
bacterial growth. The bacteria are known as Acetobacter aceti,
which are able to survive in an acid environment with a pH of 4.
– the bacteria have an orange color and are not harmful to humans.
These bacteria are about 0.6 micron in diameter and 4 microns in
length, which is relatively smaller than most common bacteria.
– the bacteria form tiny chained particles that can clog injectors.
– the bacteria generate an acetic acid during the growing process,
which may subsequently corrode the underground tanks.
Acetobacter aceti
• Requires oxygen to grow; no evidence
showing that it is a threat to humans
• Causes some detrimental effects on
pineapples. - the pink disease
• Used in the production of vinegar by
converting the ethanol in wine into acetic acid
• Able to survive in acidic environments
Underground ULSD Storage Tank
Owners
• Keep water and ethanol out of the tanks
• Practice good housekeeping
• Do not share a common ventilation system
with that of gasoline
• To minimize mis-fillings, follow the
recommended API Product Delivery Color
Code for the UST.