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Air Care News
April 2002

Tech Night Fuel presentation
by Jim Kemper

Does today’s fuel still cause driveability problems? If so, how often do they occur?

These were the main topics of discussion at a recent Tech Night sponsored by the Colorado Department of Public Health and Environment. Three fuel specialists presented information about Colorado fuels to more than 80 participants at the Aurora Emissions Technical Center. The session explored fuel testing, composition, and common fuel quality issues. 

Fuel Driveability and Future Trends
Kim Livo - Colorado Department of Public Health and Environment

Livo reviewed the role fuel plays in the performance and driveability of motor vehicles.

Time and technology have changed the composition of gasoline. Several competing influences affect its quality and composition. They include: vehicle design, fuel requirements, the availability of different grades of gasoline and their prices, emission effects, and national energy policy concerns.

Fuels, Livo said, affect driveability. The major influences are volatility, purity, and octane ratings. A range of volatility is needed throughout the year; a fuel that gives good driveability in the winter may cause vapor lock in the summer. A summer fuel, giving excellent driveability on the hottest day, may not allow a car to start at 10 degrees below zero.

Gasoline composition has changed over time to reflect new and different needs. The two biggest changes were the introduction of high compression engines in the 1930s and unleaded fuel in the 1970s. As octane requirements increased through the 1960s (remember high compression engines?), the use of tetra ethyl lead rose in proportion. Also, volatility increased as fuel was more intensively refined to achieve a higher octane. Vapor pressures increased even more with the introduction of unleaded gasoline and when oxygenates were introduced to either extend gasoline supplies or raise octane. The late 1970s and 1980s saw increases in aromatic and olefin content that caused deterioration problems with some rubbers and plastics.

By the 1990s, fuel volatility was lowered, lead was phased out and benzene content was capped. Sulfur levels became a concern because of the negative effect on catalytic converters. Today, sulfur content is being reduced and will be nearly eliminated by the end of this decade.

While some fuel problems still exist (mostly water contamination), better refining techniques, tighter state controls, and better monitoring have eliminated many of the problems experienced in the late 1970s and 1980s. With few exceptions, today’s fuel retailers deliver a good quality product that continues to be improved.

Tech Nights are sponsored by the Colorado Department of Public Health and Environment as a service to the automotive repair industry. Voluntarily registered repair shops are automatically notified by mail of upcoming Tech Nights.

 
Fuel Composition
Dennis Creamer - Conoco

Dennis Creamer, a chemist from Conoco, Inc., described fuel refining processes and composition properties. Gasoline comes from a variety of crude oils. The principal types are known as "sweet" and "sour" crude. Sweet crude is found in the Julesburg basin area of Colorado as well as other locations worldwide. It tends to be lower in sulfur and tastes sweet. Sour crude tends to be heavier, requires more refining, and usually has a sour taste because of its higher sulfur content. Most of the crude oil that Conoco uses to supply the Colorado market comes from Wyoming, Northern Colorado, and Canada. Creamer emphasized that, while all crude oils are not the same, all gasoline must meet specifications set by the American Society for Testing and Materials, the U.S. EPA, and the State of Colorado.

Creamer presented additional information on the vapor pressure, octane, and oxygen content of Colorado fuels. Vapor pressure standards, he said, are set to maintain good driveability and to control evaporative emissions. A maximum of 8.5 pounds Reid Vapor Pressure (RVP) is standard. In the winter, up to 15 pounds of RVP is permitted, to ensure good cold starting ability. However, about 12.5 pounds is a more typical value.

Octane levels also are tightly controlled. Regular-grade gasoline averages about 85 octane, mid-grade about 87 and premium about 91. Because altitude and climate influence octane requirements, cars and trucks in Colorado usually do not need fuels with as high an octane as in some other states to operate well.

The boiling range of gasoline sold in Colorado ranges from about 50 to 420 degrees Fahrenheit. During the winter, the addition of ethanol is required and is generally blended at about 8 to 10 percent by volume. The addition of ethanol can raise gasoline vapor pressures by up to one pound and octane about two points. This results in a slightly more volatile fuel throughout the boiling range.

Creamer emphasized that the primary goal of the refiner is to produce quality, reliable fuel.

 
Fuel Testing
Joe'l Robinson - Colorado Division of Oil and Public Safety

Joe’l Robinson of the Colorado Division of Oil and Public Safety discussed state testing activities performed on gasoline and diesel fuels.

Testing is grouped into three main categories: routine, public complaint, and technical assistance. Routine testing analyzes samples from refineries, bulk plants, and retail stations as part of regularly scheduled testing. Public complaint testing is based on a complaint from the public and is given priority for both sampling and analysis. Technical assistance testing is done in cases where an individual wanting a test brings a sample to the laboratory. Generally, fleet operations use this type of test to help determine the age of the product in their tanks, water quantity, and other fuel quality issues.

The state laboratory measures a variety of fuel parameters. However, there are five key tests: vapor pressure, oxygen content, octane rating, distillation properties, and water tolerance.

Vapor Pressure
The vapor pressure test is important because it measures how volatile the fuel is, or how easily it evaporates. Vapor pressure has to be high enough for easy vehicle starting, yet low enough to prevent vapor lock and/or excessive emissions. Vapor pressures are adjusted seasonally to reflect changes in temperature and climate. Vapor pressure tends to be higher in the winter and lower in the summer. 

Oxygen Content
Fuels are tested for presence and volume of oxygenates such as alcohols (ethanol), and ethers ( MTBE or TAME). This is especially important during the oxygenated gasoline program that runs from November to February each winter, and is designed to reduce carbon monoxide emissions.

Distillation Properties
Distillation properties of fuel are related to volatility. The fuel is heated while the volume is measured per degree of temperature increase. As the temperature increases, the fuel slowly evaporates until no more liquid is left. At this point, a final temperature reading is made. Specific amounts of fuel (10, 50 and 90 percent) must be evaporated within specific temperature ranges.

Octane Rating
This index rates the ability of gasoline to resist knock. Engine knock occurs when a fuel auto-ignites ahead of the spark flame front. Prolonged knocking causes power loss and, if severe enough, can lead to engine damage. Two octane engines are utilized for this test. Each measures fuel octane, but under different conditions. The first engine measures the Research Octane, or the ability of the fuel to resist knock under milder operating conditions. The second measures Motor Octane, or knock resistance under more severe conditions. Posted retail octane numbers are an average of these two different measurements: Research number plus Motor number divided by two {(R+M)/2}. At a minimum, retail gasoline must meet the posted octane, although it can be higher.

Water Content
Fuel quality has improved dramatically in recent years with fewer problems existing today than in the past. Of the problems that do exist, water contamination is the most common. This is more prevalent in the winter when melting snow can leak past faulty tank seals. The main goal of the testing laboratory, said Robinson, is to monitor and help maintain the quality of gasoline and diesel fuel in Colorado. For more information or to submit a sample, please call the Technical Assistance Hotline, 303-318-8547.

For more information on becoming a voluntarily registered repair shop, or for more information on upcoming seminars, please contact Jim Kemper at (303) 692-3125.

Jim Kemper is an Air Environmental Protection Specialist with the Colorado Department of Public Health and Environment.

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Vouchers can be costly problem if used incorrectly
by Tom Myrsiades

Licensed Colorado car dealers have been using emissions vouchers as a convenient, cost-effective way of having vehicles emissions tested since 1997. Colorado law allows car dealers to provide emissions vouchers to customers living in the Denver metro enhanced emissions program area instead of having vehicles emissions tested prior to sale. Despite the convenience and legality, the Colorado Department of Revenue (DOR) occasionally receives complaints concerning the use of vouchers.

When a voucher is not utilized as intended, a routine used car sale can become a costly problem for the consumer or the dealer. The case of a Denver area franchise dealer who sold a used car to a Greeley resident is a good example. Greeley is in the basic emissions area, while Denver is in the enhanced area. The dealer gave the customer a voucher at the time of sale. The customer drove the vehicle for two months and then took it to an independent emissions testing facility in Greeley. The car failed and the customer discovered that the proper repair would exceed the actual value of the vehicle. The customer contacted the dealer in an attempt to obtain repairs, but the dealer declined responsibility, citing that the three-day return period had expired. A complaint was filed with the DOR, and an investigation determined that the vehicle was sold illegally. The dealer in this case should not have sold a vehicle to a basic area motorist with an enhanced voucher. The dealer then had to buy the vehicle back from the customer and incur all costs related to that sale.

Another common complaint from consumers is that they are not given a voucher at the time of sale. These complaints generally are resolved quickly by reviewing the dealer's files. Dealers should keep a signed and dated copy of the voucher with the Vehicle Identification Number (VIN) of the vehicle in question.

Other complaints involve dealers that exhibit the spirit of the law by providing the consumer with a personal check intended to cover the cost of an enhanced test, or a written promise to pay for the emissions test. The consumer will then file a complaint with the DOR when the vehicle fails the test or develops problems before it passes the emissions test. Dealers generally end up mitigating these complaints even though their intentions were well founded.

One of the most frequent infractions is failure on the dealer's part to properly fill out the voucher with the date, VIN and signature of the customer.

If you have any problems or questions concerning this law, call the DOR Motor Vehicle Emissions program, 303-205-5603.

Tom Myrsiades is an Emissions Compliance Supervisor at the Colorado Department of Revenue.

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