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What is bio-diesel?
Bio-diesel is a name used for cleaner burning alternative fuel produced by domestic, renewable resources. It contains no petroleum, but can be blended at any level with petroleum diesel to create a bio-diesel blend. It can be used in compression-ignition diesel engines without major modifications. Bio-diesel is simple to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics.

Technical Definition:
A fuel composed of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, designated B100, and meeting the requirements of ASTM (American Society of Testing & Materials) D 6751.

How is bio-diesel made?
Bio-diesel is made through a chemical process called transesterification whereby the glycerin is separated from the fat or vegetable oil. The process leaves behind two products; methly esters (the chemical name for bio-diesel) and glycerin (a valuable byproduct usually sold to be used in soaps and other products.)

What is the difference between B5 & B20?
Bio-diesel can be used as a pure fuel or blended with petroleum in any percentage. A blend of 5% bio-diesel and 95% by volume of petroleum diesel called B5 has shown improvements in performance, enhanced lubricity and some reduction in emissions. A blend of 20 percent by volume bio-diesel with 80 percent by volume petroleum diesel called B20, has demonstrated significant environmental benefits with minimum cost increase.


What is E85?
E85 is the term for motor fuel blends of 85 percent ethanol and just 15 percent gasoline. E85 is an alternative fuel as defined by the U.S Department of Energy. Ethanol burns cleaner than gasoline; it is a completely renewable fuel.

What is Ethanol?
Ethanol is an alcohol made from corn and other starch crops like barley and wheat that have been converted into simple sugars and then fermented and distilled.

What is the difference between E85 & E95?
E85 (a blend of 85% fuel ethanol and 15% gasoline) is used in spark ignition engines (i.e. gasoline engines). The gasoline is added to provide good cold start and warm up performance due to ethanol’s low volatility, which results in more difficulty vaporizing at cold starts. E95 (a blend of 95% fuel ethanol and 5% gasoline) is used in compression ignition engines (i.e. diesel engines). The addition of gasoline above five percent in diesel applications lowers the flash point to unacceptable levels.

What is a flexible fuel vehicle?
Flexible Fuel Vehicles, also known as FFVs, are designed to run on gasoline, E85, or any combination of the two. The “Flexible” nature of the vehicle gives the driver the flexibility to switch back and forth between gasoline and E85. How can this be?

Ethanol contains more oxygen than gasoline. The vehicles come equipped with an oxygen sensor which determines the amount of ethanol in the fuel at any time. It provides this information to the onboard computer, which then adjusts the engine to maximize efficiency and performance. The fuel may contain anywhere from zero to 85% ethanol.


Ethanol is a clean-burning, high-octane fuel that is produced from renewable sources. Ethanol is grain alcohol, produced from crops such as corn. Because it is domestically produced, ethanol helps reduce America’s dependence upon foreign energy sources.

Pure, 100% ethanol is not generally used as motor fuel; instead, a percentage of ethanol is combined with unleaded gasoline. Ethanol blends are beneficial because:
          • Fuel cost decreases
          • Fuel octane rating increases
          • Harmful gasoline emissions decrease

Any amount of ethanol can be combined with gasoline, but the most common blends are these:

E10 - 10% ethanol and 90% unleaded gasoline
Blends up to 10% (E10) are approved for use in any make or model of vehicle sold in the U.S.. Many automakers recommend its use because of its high performance and cleanburning characteristics.

E85 - 85% ethanol and 15% unleaded gasoline
E85 is an alternative fuel for use in Flexible Fuel Vehicles (FFVs). There are currently more than 4 million FFVs on America’s roads and automakers are rolling out more each year. In conjunction with more flexible fuel vehicles, more E85 pumps are being installed across the country. When E85 is not available, these FFVs can operate on straight gasoline or any ethanol blend up to 85%. The National Ethanol Vehicle Coalition and the U.S. Department of Energy recommend 1 micron filtration for E85 applications. For filtration of E85, use Bio-Tek® 1 micron High Bio Content Filters. General Motors Corporation®, the Ford Motor Company ® and Cim-Tek® Filtration are all members of the National Ethanol Vehicle Coalition.

Did You Know?
In a 10% Ethanol Blend, it takes as little as 18 gallons of water in a 6,000 gallon tank to cause Phase Separation. In a 2% blend it takes only 3.6 gallons to cause Phase Separation!

Phase Separation
The worst enemy of any ethanol blend is water. The potential for Phase Separation requires that gasoline oxygenated with ethanol not be exposed to water during its distribution or use in a vehicle. Because of this requirement, gasoline oxygenated with ethanol is usually not transported in pipelines, which sometimes contain water. Rather, the ethanol is usually added to tanker trucks at the terminal immediately before delivery to the service station.

If water contaminates the fuel, the water dissolves into the ethanol and disperses through the tank. Once it exceeds the tolerance level, the alcohol water mixture will separate from the gasoline. Depending upon individual conditions, about 40% to 80% of the ethanol will be drawn away from the gasoline by the water, forming two distinct layers. The top layer will be a gasoline that is a lower octane and perhaps out of specification, while the bottom layer is a mix of water and ethanol that will not burn. This is Phase Separation.

Housekeeping at the service station is very important to prevent water contamination.


          • Ethanol-compatible water detecting paste should be used to test your tank for Phase Separation.
          • During the first 48 hours from conversion, the tank should be tested at regular intervals.
          • Immediately stop the sale of the product if a phase separated layer is detected.
          • Check product quality at the nozzle for clarity. Hazy or cloudy product indicates the presence of a phase separated layer.
          • Determine if water has leaked into the tank or if a recent delivery was contaminated.
          • Immediately call your fuel supplier to analyze the fuel and take appropriate steps to reblend the ethanol and gasoline to the correct octane levels.
          • Pump off the phase separated layer and dispose of the product in accordance with local, state, or federal regulations.
          • Deliver sufficient enriched ethanol-blended gasoline so as to fill the tank to 90% of capacity and to the right octane level. This will minimize the effect of any residual water.
          • Install new Bio-Tek® Alcohol Monitor Filters.
          • When delivery is complete, purge all island pumps until the product is clear. After gasoline from all dispensers is checked and found to be clear, the product may be sold.
          • If there is a Bio-Tek® Alcohol Monitor filter installed and the fuel flow slows to 2 GPM or less, immediately check for Phase Separation.

Remove water BEFORE it becomes a problem!
Design and follow a Daily Maintenance Program


For Ethanol Blends up to E10

Since ethanol blends will scour contaminants from the sidewalls and the bottom of the storage tank, it is strongly recommended that a high performance dispenser filter be used. The storage tank can accumulate a large amount of particulates that are typically mixed with water.
Normal dispenser filters will prevent contaminants from reaching the customer’s fuel tank, but they will not detect Phase Separation. It is essential that all water is out of the tank and recontamination does not occur before or after adding an ethanol blend to the tank.

There are many ways for water to contaminate the tank:
          • water accumulation around the fill gauge manhole
          • secondary containment submersible pump pits
          • faulty gaskets
          • loose fill caps
          • leaky fittings
          • a leak in the tank.

Most tank gauging systems are not effective at measuring water below ¾ of an inch. Removal of tank bottom water and contaminants is recommended before introducing an ethanol blend. Most tanks are equipped with ½ inch thick gauge plates under the tank openings.
This construction can mask as much as ten gallons of water in tank bottoms. Tank tilt can also mask significant quantities of water. You must sample your tank. The worst enemy of ethanol blends is water. Depending on the temperature of the fuel, as little as 0.3% water can cause Phase Separation. A tank with a history of bottom water contamination is certain to present problems unless the cause of water buildup is addressed. Tanks must be prepared by taking steps to keep ground water from accumulating around the fill, gauge and submersible pump pits. All tanks must be water-tight prior to conversion.


Recommended Housekeeping Procedures For Ethanol Blends up to E10

         • Keep fill caps secure at all times.
         • Respond to any customer complaints immediately by checking for Phase Separation.
         • Monitor the dispenser for good flow.
         • Change Bio-Tek® Alcohol Monitor filters when flow is restricted and check for phase separation. Contaminants and Phase Separation can both contribute to filter clogging.
         • Always keep extra Bio-Tek® Alcohol Monitor filters on hand.
         • Monitor fill opening and driveway covers for standing water. Correct this problem immediately.
         • Clearing snow buildup to prevent melting snow from leaking into the fill opening.
         • Monitor for Phase Separation with ethanol compatible detection paste.
         • If a layer is detected, follow the recommended “Phase Separation Guidelines”.
         • Take regular tank samples. Remember tank tilt and tank gauge plates can mask water.
         • Remember that most tank gauging systems may not be effective at measuring water below 3/4 of an inch.

Also, it is very important that you clean your tank and take samples. Older tanks or tanks that are not equipped with pressure vents may require special cleaning. The Cim-Tek® Cim-Cart IV contaminant removal system removes water and contaminants from the bottom of the tank. It snakes along the bottom of the tank removing water and particulates while the station is in operation. There are some cases where another method of cleaning may be required. Please contact Central Illinois Manufacturing Company for more information.


Recommended Housekeeping Procedures For Ethanol Blends up to E10

When the initial load arrives, follow normal delivery procedures. Take stick and pump readings for an accurate inventory record. After the initial delivery, it is recommended that operators dispense a few gallons of product through each dispenser to ensure the product is clear. The best defense for preventing Phase Separation is implementing a daily maintenance routine. Installing Bio-Tek® Alcohol Monitor filters upon the introduction of an ethanol blend into your tank is strongly recommended. The Alcohol Monitor will filter out the contaminants while monitoring for Phase Separation. Once the Bio-Tek® Alcohol Monitor detects Phase Separation, it will restrict the flow signaling the station operator. Use ethanol compatible phase detecting paste such as Sar-Gel® Indicator Paste or Gasoila® All-Purpose Water Finding Paste to check for Phase Separation. Make sure to discard any paste that will not allow you to detect Phase Separation.

          • Upon the introduction of an ethanol blend, immediately check for Phase Separation.
          • For the first 48 hours of ethanol in the tank, check for Phase Separation every few hours.
          • Install Bio-Tek® Alcohol Monitor filters.

If you own or manage a service station and want to make sure you're bio-diesel ready, then download our handy bio-diesel conversion checklist HERE in PDF format.