A Comprehensive Analysis of

Current Research on E15

Dispensing Component Compatibility

March 2012

Larry Gregory Consulting, LLC

Snoqualmie, WA

larry.r.gregory@gmail.com
Table of Contents

 

Executive Summary 1

Project Scope of Work 3

Summary of Papers

1. ORNL Elastomers, Metals and Sealants 4

2. NREL Dispensing Equipment Testing 7

3. GAO Challenges to the Use of Ethanol Blends 9

4. Ken Wilcox Stage I and Overfill Components Testing 12

5. NREL Headspace Flammability Tests 2008 14

6. NREL Headspace Flammability Tests 2010 17

7. NREL Headspace Flammability Tests 2011 19

8. SwRI Flame Arrester Literature Review 20

9. USEPA Notice of Guidance on E-15 Compatibility 21

10. ORNL January 5, 2012 Webinar Presentation 23

Conclusion 25

Risk and Mitigation Summary 26

Appendices 30
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Executive Summary

Several research papers have been published on the effects of increasing the ethanol blend ratio to E15 

from the current E10 standard. The following information can be concluded from this research:

The Oak Ridge National Laboratory (ORNL) issued a report on elastomers, metals and sealants that was 

designed to provide guidance and identify potential issues to service station equipment designers. They 

found very little corrosion of metals while all elastomers (i.e., gaskets, seals, o-rings, etc.) swelled and 

most lost important qualities which can result in leaks. They concluded that some elastomers are not 

suitable for E15, while others require expert design to function well. Thread sealant designed for higher 

blends of ethanol work well while pipe joints with older thread sealant leaked with E15. The 

information presented by ORNL may be useful to service station equipment designers. 

The National Renewable Energy Laboratory (NREL) and Underwriters Laboratories (UL) tested a number 

of samples of used and new service station equipment. All the equipment was listed for E10 but was 

tested with E17a, an aggressive laboratory test fluid, after soaking the equipment in the test fluid at a 

high temperature (140°F) for 105 days. They found that 70% of the in-use equipment and 40% of the 

new equipment failed compatibility tests. Their conclusion was that “no clear trends in the overall 

performance of all equipment could be established.” However, the results from these tests are far from 

inconclusive; these tests found a reduced level of safety from using equipment certified for E10.

The U.S. Government Accountability Office (GAO) reported on challenges related to E15 

implementation. They noted that U.S. Occupational Safety and Health Administration (OSHA)

regulations require all service station components from the dispenser nozzle to the submersible turbine 

pump (STP) to be listed by a nationally-recognized testing laboratory (NRTL). Despite this, “the vast 

majority of existing retail dispensers in the United States are not approved for use with intermediate 

ethanol blends under OSHA’s safety regulations.”

1 GAO was also concerned that many service stations 

lacked the records required to verify compatibility with E15 as well as the limited amount of research 

that has been conducted so far. Service station owners face challenges from using existing equipment 

to sell E15 because, “ongoing federal research indicates potential problems with the use of intermediate 

ethanol blends with some UST components.”

2

 These challenges include costs of equipment upgrades, 

logistical limitations on the types of fuel a retailer may be able to sell, and legal uncertainty about 

whether existing dispensing equipment can be lawfully used with intermediate ethanol blends. 

Ken Wilcox Associates tested Stage I vapor recovery and overfill protection components in both E10 and 

E17a fuel samples. He found that fill swivel adapters failed to pass UL tests after exposure to E17a. One 

overfill valve failed the E17a tests, while all other equipment that included ball float valves, spill bucket 

drains and pipe caps passed all tests. Wilcox also noted that many of the gaskets between the devices 

and pipes they are mounted to failed after 30 days exposure to the test fuels. 

NREL and the Nexum Research Corporation did three rounds of testing between 2008 and 2011 to 

determine the flammability of the headspace (i.e., the area above the liquid) inside of underground 

storage tanks with various combinations of gasoline and ethanol. They found that there was little 

flammability difference between E10 and E20-E30. They also found that storage of E85 and neat or fuel 

 

1

GAO Report, p. 23. 

2

Ibid., p. 26. 
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grade ethanol (E98–E100) could have flammable headspace vapors during normal operating 

temperatures.

The Southwest Research Institute (SwRI) conducted a literature search for the American Petroleum 

Institute (API) to determine if flame arresters or pressure/vacuum valves are useful with gasolineethanol blends. They found only one European recommendation for flame arresters when storing E30 

or higher. They noted that properly designed flame arresters on tank openings would only add to 

overall safety, and that failure to use compatible materials may result in leaks and an increased risk of 

fires.

The U.S. Environmental Protection Agency (EPA) issued official guidance on how service station owners 

can determine and document equipment compatibility with E15. Owners can choose to follow the 

recommendations of API 1626 (2010) or:

 Use components that are certified or listed by a nationally recognized independent test 

laboratory for use with the fuel stored.

 Use components approved by the manufacturer to be compatible with the fuel stored. EPA 

considers acceptable forms of manufacturer approvals to: 

o Be in writing;

o Indicate an affirmative statement of compatibility;

o Specify the range of biofuel blends the component is compatible with; and 

o Be from the equipment manufacturer, not another entity (such as the installer or 

distributor; 

 Use another method determined by the implementing agency to sufficiently protect human 

health and the environment.

The only alternative to these methods is to not store or sell E15 at sites with incompatible equipment.

In a January 2012 webinar, ORNL issued preliminary results on their study on plastics in mid-level 

ethanol blends. Subsequently a March 2012 draft report provided more detailed information on plastic 

compatibility but makes no specific product recommendations. The final report will be available in a 

few months.

Conclusion

Retailers choosing to sell E15 are required by OSHA and fire codes3to use listed equipment, and EPA 

rules require that equipment be proven compatible with E15. The result is that very few sites will be 

able to sell E15 fuel with existing equipment. Equipment modifications could be as little as new hanging 

hardware (i.e., hose, nozzle, etc.) or as much as an entirely new fuel dispensing system. 

Additionally, selling E15 may increase the risk for staff and customer safety, and present environmental 

consequences. The possibility of customer misfueling and the adverse effects of E15 on vehicle engines 

are also issues that should be considered. The only alternative is to not store E15 at the facility.

 

3

See Appendix 1 – E10+ and Biodiesel Compatibility Matrix.
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Project Scope

Complete a report summarizing the research results completed to date on the effects of storing and 

dispensing E15. The research completed so far has focused on individual components comprising the 

retail storage and dispensing system. It is necessary to draw a complete picture based on the results of 

the current research in order for owners and operators of retail fuel dispensing facilities to make 

informed judgments regarding whether to store and dispense E15 at their facilities.

Requirements:

1. Complete a report summarizing the research results completed to date on the effects of storing 

and dispensing E15 with the existing retail fuel distribution infrastructure.

2. Complete an analysis of the results that determine what risks, if any, exist for fuel dispensing 

facility owners and operators wishing to store and dispense E15 using their existing fuel 

distribution infrastructure. These risks must address safety risks to consumers and fuel 

dispensing facility workers as well as environmental risks.

3. Identify possible mitigation measures to address those risks.

Existing research that will be analyzed and summarized includes:

1. Intermediate Ethanol Blends Infrastructure Materials Compatibility Study: Elastomers, Metals, 

and Sealants (ORNL 2011). <www.pei.org/frg/ornl.pdf>.

2. Dispensing Equipment Testing with Mid-Level Ethanol/Gasoline Test Fluid (NREL 2010).

<www.nrel.gov/docs/fy11osti/49187.pdf>.

3. Biofuels: Challenges to the Transportation, Sale, and Use of Intermediate Ethanol Blends (GAO 

June 2011). <www.gao.gov/products/GAO-11-513>.

4. Testing the Functionality of Stage I Vapor Recovery and Overfill Prevention Components (API 

September 2011).

5. Experimental and Modeling Study of the Flammability of Fuel Tank Headspace Vapors from High 

Ethanol Content Fuels (NREL 2008). <www.nrel.gov/docs/fy09osti/44040.pdf>.

6. Experimental and Modeling Study of the Flammability of Fuel Tank Headspace Vapors from 

Ethanol/Gasoline Fuels, Phase 2: Evaluations of Field Samples and Laboratory Blends (NREL 

2010). <www.nrel.gov/docs/fy11osti/52043>.

7. Experimental and Modeling Study of the Flammability of Fuel Tank Headspace Vapors from 

Ethanol/Gasoline Fuels; Phase 3: Effects of Winter Gasoline Volatility and Ethanol Content on 

Blend Flammability; Flammability Limits of Denatured Ethanol (NREL July 2011).

<www.nrel.gov/docs/fy11osti/52043.pdf>.

8. Literature Review of the Usefulness and Efficacy of Flame Arresters and Pressure/Vacuum Valves 

with Gasoline-Ethanol blends (API 2010)

9. Guidance On Compatibility of UST Systems With Ethanol Blends Greater Than 10 percent and 

Biodiesel Blends Greater Than 20 percent (76 FR 39095, July 2011).

<www.gpo.gov/fdsys/pkg/FR-2011-07-05/pdf/2011-16738.pdf>.

10. Compatibility of Fueling Infrastructure Materials in Ethanol Blended Fuels. (Webinar: ORNL 

January 2012; Draft Report: March 2012.).
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Summary of Research

1. Intermediate Ethanol Blends Infrastructure Materials Compatibility 

Study: Elastomers, Metals and Sealants (ORNL 2011)

Background

ORNL was contracted by the U.S. Department of Energy to evaluate the impact of intermediate blends 

of ethanol and gasoline on metals, elastomers, plastics and sealants. This study used four different fuels 

based on ASTM specifications: Fuel C, CE10a, CE17a and CE25a. Fuel C was representative of highly 

aromatic gasoline. The others are blends of Fuel C with an aggressive ethanol. Accordingly, Fuel CE10a 

is 90% Fuel C and 10% aggressive ethanol. Ethanol is made aggressive with the addition of water, 

sodium chloride (salt), dilute acetic and sulfuric acids. All of these chemicals are within the bounds 

allowable for fuel-grade ethanol.

Metals investigated were 1020 carbon steel, 304 stainless steel, 1100 aluminum, nickel 201, cartridge 

brass, phosphor bronze and terne-plated steel. Corrosion was measured by weight loss. Additionally 

specimens of steel, brass and aluminum were coupled with lead, zinc, chromium and nickel to create 

galvanic corrosion conditions.

Elastomers classes included fluorocarbon, fluorosilicone, silicone, acrylonitrile butadiene rubber (NBR), 

styrene butadiene rubber (SBR), polyurethane and neoprene. 

Two pipe thread sealants were evaluated in some of the fuel samples as part of the tests. One sealant 

has been used historically. The other was specifically designed for use with E10 and E85.

Metal Results

Very little corrosion was found on any sample in any of the fuel types. While some slight discoloration 

was reported, no corrosion was found on any sample exposed in the vapor regions of the test chambers. 

None of the plated specimens showed accelerated corrosion due to galvanic coupling between the

material and substrate. 

1020 mild steel, 1100 aluminum, 201 nickel, and 304 stainless were found to be essentially immune to 

corrosion. Accordingly, these materials are suitable for use with intermediate ethanol blends used in 

this study. Cartridge brass, phosphor bronze, zinc-plated (galvanized) steel and lead-plated (terne) steel 

had some discoloration and minor corrosion film formation. They were considered to have a low rate of 

corrosion in these test fuels. Additionally, they found that there was no trend in the corrosion rate of 

materials as a function of the ethanol concentration in the fuel. None of the plated materials coupons 

exhibited any discoloration or measurable corrosion or any accelerated corrosion from galvanic coupling 

between the plating material and substrate.

Elastomer Results

Elastomers are used to seal equipment components so that they do not leak. Elastomers are also part of 

flexible hose. 
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All of the elastomers exhibit some level of volume swell that could lead to possible problems with some 

seal designs. Ethanol was found to further increase the amount of swell and produced softening. CE10a 

or CE17a produced more swell than Fuel C or CE25a. This suggests that the highest level of solubility for 

elastomers occurs at a relatively low concentration of ethanol.

Fluoroelastomers (fluorocarbons and fluorosilicone) had the best retention of properties with volume 

swell under 20%.

Silicone rubber had volume swell over 120% but did not suffer any structural degradation from exposure 

to test fluids.

NBR and polyurethane showed pronounced increase in volume swell and softening. These two types of 

elastomers were also the only samples showing embrittlement when dried. This indicates that 

plasticizer components were being removed by the test fuels. Polyurethane may not be useful in any 

sealing applications for fuel containing up to 25% ethanol.

The SBR sample had the highest combination of swell and softening. Nevertheless, appropriate 

formulations of the material may be suitable to meet some sealing specifications for fuel grade ethanol.

Neoprene had similar performance to NBRs. Exposure to fuel left the sample in a less durable condition.

Vapor-only exposure to the test fluids exhibited similar results to those found with the wetted 

specimens. 

Sealant Results

Standard thread sealant did not pass exposure to either CE10a or CE25a. Combining Teflon tape with 

this standard sealant prevented leaks from occurring. The report failed to note that many 

manufacturers warn installers to never use Teflon tape in fuel system installations.

The ethanol-resistant sealant prevented leakage in the CE10a and CE25a fuels. 

Other

Appendix A of the report investigated the faceplate rubber cork seals that had been found leaking in the 

earlier UL/NREL testing. They found indications that the elastomer component of the seals was 

effectively dissolved by the test fuel and resulted in the leakage observed. The elastomer component is 

necessary for seal strength and elasticity. The selection of a proper rubber component for these seals is 

necessary to prevent leaks from exposure to ethanol blends.

Additional Comments

Copper was not included in the test metals. Copper was used in the past in a significant number of 

dispensers. Internationally, some underground product piping is also copper.
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The information presented on materials may be useful to service station equipment designers. Owners 

or operators will have to rely on the methods identified by EPA and/or API 1626 (2nd edition) to 

determine equipment compatibility.
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2. Dispensing Equipment Testing with Mid-Level Ethanol/Gasoline 

Test Fluid (NREL 2010)

Background

This report documents work done by Underwriters Laboratory (UL) and the National Renewable Energy 

Laboratory (NREL) to better understand any potentially adverse impacts from dispensing fuel with 

higher levels of ethanol than what the equipment was designed to dispense. 

The project tested new and used equipment that was UL listed for E10 using the UL 87A standard for 

testing equipment for dispensing fuel with an ethanol content of up to 85%. The only change was the 

use of CE17a test fluid.4The primary goal of the work was to identify leaks and assess other safety 

related performance requirements. Work was conducted at a UL laboratory.

The overall assessment of the results was that they were inconclusive insofar as no clear trends in the 

overall performance of all equipment could be established. Some equipment performed well with the 

test fluids. Other equipment demonstrated a reduced level of safety. Problems with gaskets and seals 

in both new and used equipment were the primary issue found.

Results of the testing may be summarized as follows: 

*Note that the values from Table 3 in the report were corrected in the table above. Table 3 did not 

accurately summarize the number of samples in the hose/hose assemblies and swivel categories. 

Additionally, the table counted incomplete submersible turbine pump (STP) and nozzle tests as 

compliant test results. A test should only be compliant if the full test is passed.

 

4

See Appendix 2 – UL Rationale for Aggressive Test Fluids. 

Equipment New Equipment Used Equipment Total New and Used Total % Compliant

Meter Manifold Valve Assembly 0 of 2 0 of 4 0 of 6 0%

STP 0 of 1 None 0 of 1 0%

Nozzles 2 of 6 1 of 4 3 of 10 30%

Breakaway 2 of 5 1 of 4 3 of 9 33%

Swivels 2 of 3 0 of 2 2 of 5 40%

Hose/hose Assemblies 8 of 9 4 of 6 12 of 15 80%

Flow Limiter 1 of 1 None 1 of 1 100%

Shear Valves 3 of 3 None 3 of 3 100%

Total 18 of 30 6 of 20 24 of 50 48%

Compliant Test Results Summary
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The same data may be re-categorized as follows:

With 70% of used equipment failing the tests, it is hard to understand how the report concluded that 

there was no clear data trend. At the extreme ends of results, shear valves and the flow limiter were 

the only equipment that always passed tests. Meter manifold and valve assemblies always failed. The 

single STP did not complete all tests. The rest of the equipment had mixed results. Given that the UL 

standard for tests is that 100% of the equipment must pass all tests to be listed, the results from these 

tests are far from inconclusive.

In summary, some equipment that is UL listed for E10 may have immediate failures while other may 

have failures over a longer time or experience a shortened overall life. In either case, the E17a tests 

found a reduced level of safety from using equipment certified for E10 with E17a.

Category New Equpment Used Equipment Total

Hanging Hardware 83% 38% 53%

Inside the dispenser 60% 0% 33%

STP 0% n/a 0%

Total 60% 30% 48%

% Compliant
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3. Biofuels: Challenges to the Transportation, Sale and Use of 

Intermediate Ethanol Blends (GAO June 2011)

Background

The U.S. Congress asked GAO to examine three issues regarding the increased use of ethanol:

1. Determine the challenges, if any, with transporting additional volumes of ethanol to wholesale 

markets.

2. Determine the challenges, if any, associated with selling intermediate ethanol blends at retail 

stores.

3. Examine research by federal agencies into the effects of intermediate ethanol on automobiles 

and stationary engines.

This summary of the GAO report only addresses issue #2 regarding potential challenges to the retail fuel 

store.

Findings

There are implementation challenges due to regulations and technical issues:

1. Federal and state regulations governing health and environmental concerns must be met before 

blends can be sold. Fuel testing time to meet these regulations will take more than one year to 

complete.

2. Federal safety standards (OSHA) do not allow ethanol blends over 10% to be dispensed at most 

retail facilities and federally sponsored research has indicated potential problems with 

compatibility of existing equipment with ethanol blends.

3. According to EPA and an industry representative, the compatibility of many UST systems is 

uncertain and retailers will need to replace any components that are not compatible with 

ethanol blends.

4. Trade groups report that fuel retailers may face significant costs such as upgrading or replacing 

equipment.

5. Industry representatives raised concerns that fuel retailers could expose themselves to lawsuits 

for negligence and invalidate important business agreements that may reference these safety 

requirements, such as tank insurance policies, state tank-fund policies, and business loan 

agreements.

6. Fuel retailers have received conflicting or confusing messages from different authorities as to

whether existing dispensing equipment can be lawfully used with intermediate ethanol blends. 

Even if state or local officials—such as fire marshals—approve the use of intermediate blends 

with existing dispensers, the retailers selling these blends would still be effectively ignoring 

OSHA’s regulations, which require the use of equipment that has been certified for safety by a 

NRTL.
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Federal and State regulations need to be met:

Specific industry standards from ASTM or NIST do not allow ethanol above E10. Either of these 

standards must be revised or the states will have to change their standards that reference these 

industry standards.

OSHA standards prohibit using existing equipment for intermediate ethanol blends unless it is UL listed

for the fuel. OSHA, however, has not yet taken any specific enforcement action or plans to educate the 

industry on requirements.

Compatibility of many UST systems with intermediate blends is unclear:

The November 2010 NREL/UL compatibility study reported that some dispenser components 

demonstrated a reduced level of safety, performance, or both when exposed to the test fluids.

In a December 2010 announcement based on this NREL research, UL stated that it advised against the 

use of intermediate ethanol blends in equipment certified for E10 and, instead, recommended the use 

of new equipment designed and certified for use with intermediate ethanol blends. UL had concerns 

with degradation of gaskets, seals, and hoses that could cause leaks.

In March 2011, ORNL subsequently published a report that stated, while most metals are unaffected by 

the test fluid, all elastomers tested exhibited some level of swelling and the potential to leak.

Inadequate record keeping may make it difficult for retailers with older stations to verify UST system 

compatibility with intermediate ethanol blends. There are also issues with information transfer 

between multiple owners of UST systems. Many installation contractors and equipment manufacturers 

may also have gone out of business.

Research so far has been limited to materials and a few unidentified UST components.

5

The EPA has not 

developed a plan to do more research on components.

EPA required leak detection systems may not properly detect leaks of intermediate ethanol blends. The 

EPA has not yet completed tests that will determine if the ethanol content of fuel would affect the 

operability of this equipment.

Retailers may face significant costs and risks in selling intermediate blends:

Retailer margins are low for fuel and most retailers will not upgrade their UST systems without a 

significant opportunity. Cost for upgrades could range from nothing to the cost of entirely new systems.

Some sites cannot install additional UST systems due to space constraints, permit requirements or cost.

Many sites currently store only two products underground and blend a third mid-grade. If a retailer 

wants to use one tank to store E15, then they could not offer fuel for vehicles made before 2001 or nonroad engines.

 

5

This assessment by GAO was made prior to the completion of Ken Wilcox’s research, detailed on page 12.
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There may be increased risk from using existing equipment to sell E15. While some local requirements 

may allow selling E15 from existing dispensers, OSHA requires that dispensing systems be UL listed. 

According to GAO, without this listing, retailers may expose themselves to lawsuits for negligence and 

invalidate important business agreements such as tank insurance policies, state tank fund policies and 

business loan agreements.

In GAO’s opinion, misfueling could raise liability issues, especially if engines have diminished 

performance or safety issues. Customers may not be aware of the distinction between fuels and may 

accidently misfuel. Some consumers will intentionally misfuel the vehicles if intermediate ethanol 

blends are cheaper.

Conclusions

The EPA and OSHA are responsible for ensuring that fuels are compatible and safe for use with 

infrastructure at fueling locations. The DOE materials report found that materials commonly used in 

gaskets or seals can swell with E15, potentially causing leaks.

While some of the latest equipment meets OSHA safety requirements for E15, most existing equipment 

at retail fueling locations is not approved for use with intermediate blends. OSHA is currently clarifying 

requirements on how OSHA safety regulations on fuel dispensing equipment should be applied to fuel 

retailers selling intermediate ethanol blends. 

The EPA has reported that they plan to issue guidance for UST owners on how to determine the 

compatibility of the tank system if they wish to store higher blends of ethanol. Despite acknowledging 

that additional research on the suitability of specific UST components with intermediate blends is 

needed, EPA’s guidance will be based on information limited to experts’ views on the subject.6 

Those owners that cannot demonstrate compatibility of their systems with the higher blends of ethanol 

cannot store those fuels.

 

6

This guidance was issued in June 2011, and is now a proposed regulation: EPA-HQ-UST-2011-0301.
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4. KWA Report – Testing the Functionality of Stage I Vapor Recovery 

and Overfill Prevention Components

Background

The objective of this report for API was to determine whether there are any adverse effects on the 

functionality of Stage I vapor recovery components and overfill protection systems when used in a 

higher alcohol blend. Equipment used successfully for many years on E10 was tested with E10 and E17a 

blends.

Approach

Equipment was first soaked in the E10 or E17a test fluid for 4 weeks at 140°F. Equipment was then 

mounted in test apparatus and cycled for up to 100,000 cycles. Identical equipment was tested in both 

E10 and E17a.

Results

Equipment tested:

Fill and vapor swivel adapters - Six of eight tests failed. 

Ball float valves - All tests passed.

Spill bucket drain valves – All tests passed.
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Flapper Valves – One of the two valves tested failed the CE17A test. All other tests passed.

Monitoring probe cap – All tests passed.

Conclusion

The primary failures observed were due to degradation of seals, gaskets or other material in the 

components under test. This raises a question about what condition these types of gaskets are currently 

in at sites selling E10 fuel.
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5. An Experimental and Modeling Study of the Flammability of Fuel 

Tank Headspace Vapors from High Ethanol Content Fuels – October

2008

Background

The project was to quantify the difference in headspace flammability hazards between E85 fuel and 

gasoline without ethanol (E0) inside of storage tanks. Headspace is the area inside of the tank that is 

not filled with liquid fuel.

Headspace vapors are mixtures of hundreds of individual pure compounds that depend on ambient 

temperature and the amount of liquid fuel in the tank. Gasoline is so volatile that at most temperatures 

the vapors are too rich to burn. 

Ethanol in a fuel tank has vapors that are flammable over a broad range of commonly encountered 

ambient temperatures.

Ethanol/gasoline blends have flammability characteristics somewhere between the properties of the 

two fluids depending on the ratio of these two main fuel components.

Specific study goals can be summarized as follows:

1. Develop the test apparatus and protocols required to conduct the study in a small-scale 

laboratory.

2. Test a series of representative samples of E85, gasoline and denatured alcohol.

3. Analyze results and draw conclusions

4. Develop mathematical models for the fuel tank tests. Evaluate the utility of modeling to assess 

fuel tank combustion hazard scenarios. 

5. Do a preliminary analysis of the flammability risk from vapor/air plumes emitted from fuel tanks 

during refueling. 

This summary report will not cover task 4.

Tests

Test fluids were seven slightly different blends of E85, two types of gasoline and denatured ethanol.

All tests were based on the flammability in a small test vessel (i.e., an explosion proof junction box) that 

was filled with 5% liquid and 95% vapors. Vapors were ignited by a spark plug. Temperature was also 

recorded by connected computer. 
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This picture of the test device was included in the report. The spark plug in the center is a good 

reference for gauging the size of the text vessel.

Results

Tank headspace vapors were measured to be flammable in the following ranges:

Gasoline: flammable at -2°F to -13°F or lower. 

E85: flammable at 28°F to -8°F or lower.

Denatured ethanol: 22°F or higher. (Colder vapors are too lean to burn)

Three E85 fuels had flammability behavior similar to the summer grade gasoline tested.

A risk identified was that when storing neat ethanol at service stations for on-site blending, the 

headspace vapor in the 100% ethanol tank would always be flammable above 22°F.

The report concluded that, at any given temperature, the more volatile the fuel, the larger the 

flammable plume from the vent gets during UST refueling. This in turn increases the risk of vent fires 

while filling the tanks with fuel. This larger plume also increases the risk of an external fire spreading 

down the vent into the tank headspace under some circumstances.

The report did not include any information on intermediate ethanol blends. It was only about the test 

fluids used. Accordingly, there is no information for retail service stations potentially selling E15 aside 

from the possible storage of neat ethanol in the future.
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Recommendations included:

1. The E85 fuels tested did not provide a blend matrix where critical components (such as ethanol 

content, vapor pressure and hydrocarbon composition) could be varied in a systematic method.

2. The study used the strong spark plug ignition source. The hazards posed by weaker sparks that 

represent actual potential ignition sources should also be investigated.

3. The tests used a 5% fill level which is a worst-case scenario for potential flammability. The 

effect of fill level on flammability should also be investigated.

4. The test apparatus needs to be refined before it can be recommended as a standard.

5. A thorough quantitative assessment is needed of the various vapor flow regimes possible during 

refueling storage tanks under different fill rates, vent geometries and weather conditions, etc.
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6. An Experimental and Modeling Study of the Flammability of Fuel 

Tank Headspace Vapors from High Ethanol Content Fuels –

Phase 2: Evaluations of Field Samples and Laboratory Blends – April 

2010

Background

This report follows up on the work done in 2008. 

The goal of the study was to measure the flammability of fuel vapors from a variety of ethanol/gasoline 

blends at low ambient temperatures and develop a mathematical model to predict the temperatures at 

which flammable vapors were likely to form.

Two sets of fuel were investigated. The first sets were sampled from a fuel dispenser. The second were 

laboratory fuels supplied by Marathon designed to simulate winter grade fuel.

Another goal was to improve the earlier modeling work. Comments are not provided on that work.

Tests

Test methods and apparatus were similar to those used in the 2008 work. The same test chambers and 

5% fill level were used.

Results, Conclusions and Recommendations

1. Some E85 tanks currently in use are likely to have flammable vapor conditions as high as 23°F; at

higher temperatures, vapors are not flammable.

2. E20 and E30 blends were sampled from a blender pump that mixed E10 with E85. No significant 

differences in flammability could be found between the E20-E30 samples and the E10 sample that 

they were produced from. These results indicate that mid-level blends in this range are unlikely to 

significantly increase the risk of producing flammable vapors over that of the base gasoline used for 

the blends.

3. Laboratory samples of E55 – E83 were produced to measure the change in flammability. 

Flammability changes from E85 decreased substantially down to E60. Lower concentrations of 

ethanol below E60 reduced the flammability at a lower rate.

4. Standards for winter gasoline and vapor pressure will probably limit the concentration of ethanol to 

a maximum of about 65%.

5. Flammability tests found that vapor pressure does not adequately predict the flammability of the 

fuel. The hydrocarbon portion of the fuel must also be considered.
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6. Additional testing is recommended to examine the effects of gasoline flammability on the vapor 

flammability of the ethanol/gasoline blends. Flammability results over a wider range of ethanol 

content are needed to understand the interactions between ethanol content, gasoline volatility, 

blend vapor pressure and vapor flammability.
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 19

7. Experimental and Modeling Study of the Flammability of Fuel Tank 

Headspace Vapors from Ethanol/Gasoline Fuels - Phase 3: Effects of 

Winter Gasoline Volatility and Ethanol Content of Blend 

Flammability; Flammability Limits of Denatured Ethanol - July 2011.

Background

This project was comprised of a study to measure the flammability of fuel vapors at low ambient 

temperatures and develop a mathematical model to predict the temperatures at which flammable 

vapors were likely to form.

This summary does not include comments on modeling.

Tests

Tests were very similar to the two previous studies.

The fuel used was produced in a laboratory to systematically investigate the effects varying ethanol 

content on the volatility and flammability of the blends. Three gasoline vapor levels were tested to 

simulate low, typical and high levels of winter gasoline. 

Results, Conclusions and Recommendations

Headspace vapor from E0 to E15 blends with winter gasoline vapor pressures were not flammable until 

temperatures were below -13F. With higher vapor pressure gasoline, the maximum ethanol content 

that would keep the same flammability level would have to be 40% or less. Accordingly, E15 vs. E10 

would not present a significant difference in flammability risk.

Further experimental work is recommended to examine the headspace vapor flammability of 

ethanol/gasoline blends made with base gasoline which have lower vapor pressure then the winter 

gasoline used so far.
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 20

8. SwRI Literature Review of the Usefulness and Efficacy of Flame 

Arresters and Pressure/Vacuum Valves with Gasoline-Ethanol

Blends - July 2, 2010

Background

SwRI conducted a literature review for API to determine the usefulness and efficacy of flame arresters 

and pressure/vacuum (PV) valves with gasoline-ethanol blended fuels. SwRI used various online journal 

and reports databases and reviewed relevant standards to conclude what guidance if any is available for 

U.S. retail stations.

U.S. retail stations do not currently utilize flame arresters to protect fuel storage tanks from outside 

ignition sources. Some European countries do use flame arresters. The purpose of this review is to 

investigate if flame arresters are necessary for safety, especially for use with gasoline-ethanol blends.

Results, Recommendations and Conclusions

This review did not find any useful history of fire events in the U.S. They also did not find any 

recommendations for flame arresters in the U.S. or anywhere else other than a UK IPEA 

recommendation that flame arresters be used on all openings to the underground storage tanks storing 

30% to 90% blended gasoline ethanol fuel.

Conclusive evidence was not found that suggests flame arresters be implemented at U.S. retail stations.

However, if properly selected, flame arresters would only add to overall safety. The report provides no 

estimate of how many fires there are today or how many fires could have been prevented with flame 

arresters.

Stage I and II vapor recovery systems may also reduce the chance of fires, but there is no detailed data 

to support this theory. Stage I vapor recovery is now installed at nearly all U.S. stations. For Stage II, the 

authors compared the frequency of fire incidents in California, where Stage II is ubiquitous, to incidents 

in other states. They concluded that Stage II contributes to a lower risk of fire incidents at retail 

stations. 

The report also recites overall recommendations on materials that are recommended or not 

recommended for E10 use. Failure to use compatible materials may result in leaks and an increased risk 

of fires.

The study recommended another study be performed to investigate the efficacy of PV valves and flame 

arresters when used with gasoline and gasoline-ethanol blends. The goals of this study would be to

determine: (1) if PV valves provide adequate fire safety, (2) the risk of flames propagating into the tank, 

(3) if flame arresters designed for gasoline are still effective when used with gasoline-ethanol blends, 

and (4) what role ethanol concentration plays in the efficacy of flame arresters. 
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 21

9. USEPA Notice of Guidance on E-15 Compatibility; Federal Register 

Publication (EPA-HQ-UST-2010-0651; FRL-9428-8)

In January 2011, EPA approved a waiver to the Clean Air Act to allow the use of E15 gasoline in 2001 and 

newer light and medium duty motor vehicles which includes cars, small trucks and some sport utility 

vehicles.

In this document, EPA issues final guidance on how owners and operators of UST’s can demonstrate 

compliance with Federal compatibility requirements for UST systems storing gasoline containing greater 

than 10% ethanol or diesel containing greater than 20% biodiesel.

This guidance applies to states and territories that do not have state program approval as well as Indian 

Country. It may also be useful for owners in states with approved programs because those programs

also include compatibility requirements. 

Because it is common for tank owners to use their tanks for 30 years or more, many UST systems 

currently in use are likely to contain components not designed to store gasoline ethanol blends over 

10%. Also, the report comments that studies so far have shown that mid-levels of ethanol (i.e., the 25% 

range) are likely to cause more compatibility problems than E85.

The guidance includes all components of the fuel system from the tank, including the shear valve. It is 

noteworthy that the requirements do not apply to dispensers and vapor recovery equipment. 

Dispensers, however, are required to have a NRTL listing by Federal OSHA regulations. Vapor recovery 

equipment is not included because it does not routinely contain liquids. The EPA rationale is that any 

incompatibility of vapor recovery equipment is not likely to result in a liquid release to the environment. 

Additionally, EPA has ruled that pipe adhesives and glues are not included because they are an integral 

part of the piping. Installers did not have discretion in the type of glue used. Additionally, owners are 

not likely to have records about what types of glues were used. Accordingly, adhesives and glues are 

covered under “piping”.

Biodiesel blends are also partially covered by this guidance. Biodiesel concentrations range from B100

(a fuel that has documented problems degrading some hose, seals, gaskets, glues, plastics, etc.) to B5-

B20 which have no history of compatibility problems. Currently, there are few installations of greater 

than B20 so little is known about compatibility. Additionally, UL does not require special investigations 

for biodiesel up to B5 that meets all ASTM fuel quality standards. Accordingly, this EPA guidance applies 

to only biodiesel blends greater than B20.

The EPA notes that these recommendations are intended solely as guidance. Compatibility 

requirements are part of CFR 280.32. Since approved state programs have the same compatibility 

requirements as CFR 280.32, they may choose to use the new guidelines for compatibility as well.
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 22

UST components that may be affected by biofuel blends of greater than E10 or B20:

 Tank or internal lining

 Piping

 Line leak detector

 Flexible connectors

 Drop tube

 Spill and overfill prevent equipment

 STP and components

 Sealants (including pipe dope and thread sealant), fittings, gaskets, o-rings bushings, couplings 

and boots

 Containment sumps (including STP sumps and under dispenser containment)

 Release detection floats, sensors and probes

 Fill and riser caps

 Product shear valves

For newly installed equipment comprised of multiple component equipment like a STP, UST owners or 

operators may obtain a certification from the manufacturer documenting compatibility for the entire 

assembly. If the equipment requires maintenance and components of that equipment such as sealants 

or gaskets are subsequently added or replaced, then manufacturer approval of the overall component 

is not sufficient to demonstrate compatibility

 

EPA recommended methods of demonstrating compatibility of UST systems with greater than E10 or 

B20 fuels include:

 Use components that are certified or listed by a nationally recognized independent test 

laboratory for use with the fuel stored.

 Use components approved by the manufacturer to be compatible with the fuel stored. EPA 

considers acceptable forms of manufacturer approvals to: 

o Be in writing;

o Indicate an affirmative statement of compatibility;

o Specify the range of biofuel blends the component is compatible with; and 

o Be from the equipment manufacturer, not another entity (such as the installer or 

distributor).

 Use another method determined by the implementing agency to sufficiently protect human 

health and the environment.

The EPA also allows owners and operators to use API RP 1626 (August 10, 2010; 2

nd Edition) to 

demonstrate compatibility for UST systems storing biofuels.

There are no other alternatives to demonstrate compatibility. If the owner or operator is not able to 

demonstrate compatibility, then EPA’s advice is not to store biofuels over E10 or B20.

State UST programs may be more stringent than EPA standards, and additional Federal, state or local 

standards (such as OSHA, the National Fire Protection Association, or the International Fire Code) may 

have other requirements. UST owners and operators should check with state and local agencies to 

determine their requirements.
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 23

10. Compatibility of Fueling Infrastructure Materials in Ethanol 

Blended Fuels (ORNL January 2012) & Draft Compatibility Study 

for Plastics, Elastomeric, and Metallic Infrastructure Materials 

Exposed to Aggressive Formulations of Ethanol-Blended Gasoline 

(0RNL March 2012 Draft)

Background

The PowerPoint document was used as part of a January 5, 2012 webinar on the research underway at 

ORNL to document the effects of ethanol blends on metals, elastomers and plastics. The report 

summarized the test methods and results included in research documents published earlier (see testing 

specified on pgs. 4 and 7), and revealed preliminary results on tests of different plastics that are used 

somewhere in fuel dispensing equipment. The March Draft Report provided additional details on the 

plastic material testing at ORNL.

The ORNL conducted tests on 22 types of plastics. Tests were run for 16 weeks versus four weeks for 

other materials. Fuels tested included Fuel C, CE25a, CE50a, and CE85a.

The goal of the testing was to measure critical plastic property changes such as volume swell, hardness, 

or mass in ethanol-blend fuels. The results are intended to be used by equipment designers (or users) 

when developing materials for ethanol-blended gasoline dispensers. The report, however, does not 

make specific product recommendations. 

Results, Recommendations and Conclusions

Results for plastic samples exposed to vapors were the same as those samples that were soaked in 

liquids. 

Seven plastics were identified as having notable results.

Nylon 12 was the only plastic that lost volume (shrunk) after being dried. Nylon 12 is most likely 

to be used in hose.

The following plastics had the greatest amount of volume increase (swell) and hardness decrease after 

exposure to the test fluids.

Nylon 11 is used in some types of flexible piping.

PP – Polypropylene is a polymer used in a wide variety of consumer products and packages. No 

specific uses in fuel system equipment are known.

PETG – Polyethylene terephthalate copolymer with cyclohexane dimethanol is used to make 

plastic parts or covers. No specific uses in fuel system equipment are known.

Vinyl ester resin may be used in tank linings.
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 24

Terephthalic polyester resin is used in the construction of fiberglass underground storage tanks.

Four samples of isophthalic polyester (without fiber reinforcement) fractured during tests with CE25a 

and CE50a test fluids. These plastics may be used in fiber reinforced plastic underground tanks, pipes or 

containment sumps. 

Test fluid evaluations after the completion of sample soaking measured high levels of phthalates. These 

chemicals are generally components of plasticizers that may be used in hose or flexible membranes in 

nozzles, valves or other products. 

The final report on plastics is expected in a few months.
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 25

Overall Conclusions & Recommendations

The NREL report on equipment compatibility found that many service station components may not be 

compatible with E15.

The ORNL report on elastomers, metals and sealants alerted designers to elastomer issues that could be 

problems when designing equipment for E15. Older designs and materials may not be compatible with 

E15.

The GAO reported that OSHA requires all components of a dispenser system be UL listed for the fuel 

grade sold. GAO has indicated that a dispenser system includes all components from the dispenser 

nozzle to the STP. Earlier listings were only valid for up to E10. If retailers dispense E15, they should 

ensure that all equipment that comes into contact with the E15 is listed for compatibility with that fuel. 

Without this listing, retailers may possibly invalidate important business agreements such as tank 

insurance policies, state tank fund policies and business loan agreements. They also note that the E15 

compatibility of many UST systems is uncertain. 

Ken Wilcox found that many gaskets for fill and adapter swivel adapters may not be compatible with 

E15. He also found problems with one overfill flapper valve. 

The NREL reports on headspace flammability found that E15 flammability is not significantly different 

than E10.

EPA provides specific guidance on how to determine if existing equipment is compatible with E15. They 

also advise that some state programs may have more stringent requirements. The only alternatives to 

their guidance are to either follow the recommendations of API 1626 or choose to not store and sell the 

E15 fuel.

Accordingly, a store owner choosing to sell E15 will incur conversion expenses that could range from as 

little as hanging hardware to as much as the need for a completely new fuel system with new tanks, 

sumps, piping, valves, fittings, dispensers and leak detection equipment. 

A store owner that does not follow this guidance faces significant risks: 

 Safety

 Environmental consequences

 Liability associated with customer vehicle or non-road engine issues

 Possible litigation

 Financial impacts
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 26

Risk and Mitigation Summary

Increasing ethanol to E15 is likely to increase the risk of operating a retail store. Possible leaks from 

incompatibility are higher than they are with E10. Risks from these releases could affect personnel and 

customer safety, the environment and the possibility of litigation. A new issue also arises with the 

possibility of misfueling that could result in engine problems with pre-2001 vehicles and non-road 

engines. Owners and operators should consider these risks and the possible financial effects on their 

business when judging whether to store and dispense E15 at their facility. 

The following service station schematic and tables are intended to approximate and suggest possible 

mitigation measures for some of the risks associated with storing and dispensing incompatible fuels at a 

service station. 
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 27

BASIC UNDERGROUND STORAGE TANK SYSTEM

1

2,3

4

6

19

7

8 11

9 12

10

13

15

18

17

14 5

20

21

22

23

24

26

25

27

28

29

30

31

32 16

Basic Underground Storage Tank System

Equipment Legend

1. Multiple Product Dispenser

2. Under Dispenser Containment Sump

3. Shear Valves

4. Seals

5. Product Pipe

6. Double- Wall Tank with Brine 

Interstice

7. Submersible Turbine Pump Manhole

8. Sump Lid

9. Tank Sump

10.Tank Sump Mounting Collar

11. Line Leak Detector

12. STP Pump Head

13. Sump Leak Detector

14. Ball Valve

15. Manway Li d

16. Flexible Connector

17. Pump and Motor

18. Tank Bottom Protector Plate

19. Tank Deadman

20. Automatic Tank Gauge Console

21. Tank Level Gauge & Manhole

22. Tank Level Water Float

23. Spill Bucket with Fill Adapters

24. Overfill Prevention Valve

25. Vapor Manhole with Adapter

26. Extractor Valve

27. Ball Float Valve

28. Vent Pressure/Vacuum Valve

29. Vent Riser

30. Brine Level Sensor

31. Tank Brine Reservoir

32. Tank Anchor Strap

33. Brine Sensor Manhole

33

Illustration adapted from and with the permission of Containment Solutions.
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 28 Part 

#

Risk Exposure to Liquid Fuel Exposure to Fire Exposure to Vapors Slip / Fall Risk Customer Off-Site Engine Failure from Bad Fuel Soil Contamination Groundwater Contamination Off- Site Structures or Land Uses Increased Air Emissions Cost of Contaminated Fuel or Released Fuel 3rd Party Claims Damage to Equipment or On- Site Structures Remediation Expense Cost of Repairs or Alterations Loss of Business during Repairs / Alterations Permanent Loss of Business to Competition Loss of Insurance or Higher Premiums Loss of Staff during Closing Possible Mitigations

Keep tank in a rich condition by increasing 

the minimum amount of fuel in the tank. 

Install flame arresters on all tank 

openings. 

Tank Lining Failure - 

Product Release x x x x x x x x x x x x x

Do not store E15 in tanks with 

incompatible or unknown linings

Tank or Lining Failure - 

Water Intrusion x x x x x x x x

Install a sensor to detect phase 

separation.

Leaks x x x x x x x x x x x x x

Use a compatible electronic line leak 

detector at the lowest possible threshold 

of detection.

Water Intrusion x x x x x x

Same as above but also install a sensor 

to detect phase separation.

Leaks from Mounting 

Threads x x x x x x x x x x

Secondarily contain the STP / line leak 

detector. Also install a secondary 

containment sensor.

Operational Failure: 

Leak Goes Undetected x x x x x x x x x x x x x Install a compatible sensor.

16 Leaks x x x x x x x x x x x

Install a compatible flex connector, only 

use flexible connectors in compatible 

secondary contained sumps.

24

Splash filling conditions 

from a broken off drop 

tube. Vapor boils out of 

the vent, fill or other 

tank opening when 

caps are removed 

increasing the chance 

of fire.

x x x x Install a compatible drop tube.

Fuel Leaks from 

Containment x x x x x x x x x x Install a compatible spill bucket.

Water is drained from 

the bucket into a 

storage tank

x x x x

Close the drain permanently with a 

compatible plug or install a new 

compatible drain plug.

E15 Gasoline - Ethanol Incompatibility Risk Table

6

5

11

23

Equipment

Line Leak detector 

(Mechanical and 

Electronic)

Drop Tubes

Spill Buckets

x

Tanks

Piping

Internal Fire or 

Explosion x x

Flexible Connectors

Risk to Customers and 

Attendants Safety

Environmental Risk Owner / Operator Financial Risk

x x x x x x x x x x x
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 29

Part 

# Risk Exposure to Liquid Fuel Exposure to Fire Exposure to Vapors Slip / Fall Risk Customer Off-Site Engine Failure from Bad Fuel Soil Contamination Groundwater Contamination Off- Site Structures or Land Uses Increased Air Emissions Cost of Contaminated Fuel or Released Fuel 3rd Party Claims Damage to Equipment or On- Site Structures Remediation Expense Cost of Repairs or Alterations Loss of Business during Repairs / Alterations Permanent Loss of Business to Competition Loss of Insurance or Higher Premiums Loss of Staff during Closing Possible Mitigations

23

Could become 

unscrewed if seals or 

gaskets swell and 

defeat swivel capability. 

Surface spill could 

result

x x x x x x x x x x x x x x x Install a compatible fill adapter.

Leak Vapors x x x Install a compatible seal on the cap.

Allow Water to Enter 

Tank x x x x x Install a compatible seal on the cap.

21,27

Failure to Operate 

Results in a Tank 

Overfill

x x x x x x x x x x x x x x x

Install a compatible overfill valve or install 

a remote overfill horn on the ATG system.

12,17 Leaks from Head x x x x x x x x x x x x x x

Install a compatible STP and compatible 

STP containment sump.

Leaks Develop x x x x x x x x x x x x x x x

Replace seals or gaskets with a 

compatible material per manufacturer's 

recommendations.

Sump material or 

penetration seal failure 

resulting in leaks from 

containment

x x x x x x x x x x x x x x

Install a compatible penetration seal and 

or new compatible sump. Possibly line 

current sump with a compatible material

Water Removal from 

Containment x x

Install a compatible penetration seal and 

or new compatible sump. Possibly line 

current sump with a compatible material.

Failure to detect a leak 

from the tank or 

containment

x x x x x x x x x x x x x x x x Install a compatible sensor.

Failure to detect water 

intrusion x x x x x

Install a compatible sensor.

Leaks x x x x x x x x x x x x x x Install a compatible valve.

Failure to stop flow 

when pump is hit x x x x x x x x x x x x x x x x x Install a compatible valve.

Internal Valves & 

Meters & Tubing 1 Leaks x x x x x x x x x x x x x x x

Install a compatible manufacturer's retrofit 

kit or replace the dispenser with a new 

compatible unit.

Slow Flow can cause 

nozzles to fail to shutoff

x x x x x x x x x x x x x x x Replace with a compatible part.

Leaks from filter seal or 

cartridge x x x x x x x x x x x x x x x Replace with a compatible part.

Breakaways Leaks, failure to 

operate x x x x x x x x x x x x x x x Replace with a compatible part.

Hose Leaks x x x x x x x x x x x x x x x Replace with a compatible part.

Swivels Leaks, failure to 

operate x x x x x x x x x x x x x x x Replace with a compatible part.

Nozzles Leaks, failure to shutoff x x x x x x x x x x x x x x x Replace with a compatible part.

3

1

Risk to Customers and 

Attendants Safety Environmental Risk Owner / Operator Financial Risk

Equipment

23 Dispenser

Product Shear Valves

Filters

Fill Adapters

Fill and Riser Caps & 

Gaskets

Overfill Prevention

Submerged Turbine 

Pump

Sealants / Gaskets

Containment Sumps

Release Detection 

Floats, Sensors or 

Probes

2,9

13,21,22
Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 30

Appendix 1: E10+ and Biodiesel Compatibility Matrix
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Comprehensive Analysis of Current Research on E15 Dispensing Component Compatibility Page 37

Appendix 2: UL Rationale for Aggressive Test Fluids

Excerpt from Dispensing Equipment Testing with Mind-Level Ethanol/Gasoline Test Fluid7:

The tests were conducted using CE17a test fluid, as defined by NREL. The test fluid was 

based on the same standard used to evaluate material compatibility for flexible-fuel 

vehicles. A 17% ethanol volumetric concentration was selected to address E15 use. This 

was not a commercial fuel, but rather a test fluid selected for research purposes. CE17a 

test fluid consists of a mixture of 83% ASTM Reference Fuel C and 17% aggressive 

ethanol. Reference Fuel C is a 50/50 v/v blend of isooctane and toluene. Aggressive 

ethanol, as defined in SAE Publication J1681, Gasoline, Alcohol, and Diesel Fuel 

Surrogates for Materials Testing, is a mixture of synthetic ethanol and the following 

aggressive elements in defined amounts: deionized water, sodium chloride, sulfuric acid, 

and glacial acetic acid. The added elements are representative of contaminants found in 

ethanol. (p. 2-3)

Excerpt from Underwriters Laboratories Research Program on Material Compatibility and Test Protocols 

for E85 Dispensing Equipment8: 

Potential fuel contaminants include water, salts, acids, and other substances. These 

contaminants may be introduced to the fuel at different points and subsequently passed

along through the distribution chain, although the fuel station level appears to present 

the highest risk point for fuel contamination. Water may be present in storage tanks 

from sources such as condensation in atmospheric tanks, ground or surface water 

entering tank seals, settling out from petroleum products in previous use, and the like.

Soluble road salts may also be present in surface water runoff and may end up in the 

fuel. Salt air condensation during sea transport or in coastal areas presents an 

additional risk of contamination from chloride compounds. Consideration of the fuel 

conductivity with absorbed water and salts is a key issue. Acids may also be introduced 

to the fuel during the production process, through oxidation of the fuel, or via surface 

water runoff. Using aggressive test fluids that include contaminants was identified as an 

important practical consideration. (p. 5)

 

7

Dispensing Equipment Testing with Mind-Level Ethanol/Gasoline Test Fluid. (NREL, November 2010). 

<http://www.nrel.gov/docs/fy11osti/49187.pdf>. 

8

Underwriters Laboratories Research Program on Material Compatibility and Test Protocols for E85 Dispensing 

Equipment. (UL, December 2007). 

<http://www.ul.com/global/documents/offerings/industries/energy/flammableandcombustiblefluids/developmen

t/E85ResearchReport.pdf>.