LOW & ULTRA LOW SULFUR DIESEL FUEL REQUIRES
ADDITIVES TO PRESERVE FUEL LUBRICITY

U.S. Environmental Protection Agency regulations requiring ultra low diesel fuel sold for highway use to be less than 15 parts per million (PPM) sulfur and with lowered aromatic content are now in effect. The environmental benefits of the regulation including a significant reduction in particulate emissions are commendable. Reducing sulfur also decreases the acids formed in engine combustion chambers, offering the promise of extended engine life. However, fuel system manufacturers are concerned that the methods used to reduce sulfur content can also impact fuel lubricity and may cause accelerated fuel system component wear.

Today, the most cost-effective way for refiners to produce low and ultra low sulfur diesel fuel is through hydrotreating, a process that removes sulfur by treating it with hydrogen. Because hydrogen is a highly reactive element, it also reacts with other components in the fuel including polyaromatic compounds thus reducing the overall content of desirable, lubricity-enhancing chemicals. Note: Ultra low sulfur diesel fuel accounts for over 80% of the on-road diesel fuel sold today. Low sulfur (500 PPM) sulfur makes up the remainder.

LUBRICITY ISSUES -

When the hydrotreating process compromises fuel lubricity, wear rates increase in many fuel injection systems, most of which are designed to benefit from the natural lubricating properties of traditional diesel fuel.

Lubricity wear problems associated with Ultra low-sulfur diesel fuels have been observed throughout North America. Problems encountered have ranged from under run/stalling annoyances to fuel pump failure requiring repair or replacement.

Lubricity problems are not new. During the Vietnam War, a manufacturer of jet engines experienced similar difficulties. In order to extend the lie of the jet fuel pumps, the military created a new fuel specification, called JPS, which greatly improved stability, lubricity and anti-corrosive properties. The additive technologies used then are available to the diesel fuel market today.

Leading diesel fuel injection equipment manufacturers in North America, and manufacturers of fuel injection pumps, nozzles, and filtration products and as such are very concerned with wear problems resulting from low-sulfur fuel.

ADDRESSING FUEL PROBLEMS -

Current testing has shown that performance-proven fuel additives do restore the lubricity of low-sulfur fuel. Quality lubricity fuel additives like FPPF products have proven that additive technology exists today which can effectively restore the beneficial fuel properties lost during hydrotreating. Injection equipment manufacturers strongly advocates the use of additives.

OFF - ROAD CONCERNS -

Injection Manufacturers also recommends the use of lubricating fuel additives for off-road applications. Off-road vehicles will be required to use low sulfur fuel (500 PPM). Starting this year, several refiners have said they will only manufacture the ultra low sulfur grade dictated by the higher demand for the on-highway regulated fuel. That means off-road vehicle users are likely to be exposed to the ultra low sulfur fuels where they fill up.

WINTER OPERABILITY -

Lowered aromatic content of low and ultra low sulfur fuels has a negative impact on Winter operability. Aromatics in the fuel help keep the fuel's paraffins from solidifying; by removing aromatics, filter plugging resulting in loss of power or engine stalling may be experienced at higher temperatures than in the past. This problem is generally worse in Winter weather making ultra low sulfur fuel even harder to treat.

In the U.S. it has been customary to "winterize" fuel to prevent filter plugging by blending # 2 diesel fuel with a lighter fuel, such as jet fuel or # 1 diesel fuel. After enactment of the diesel regulation, low-sulfur and ultra low DF#1 which has always been both rare and expensive, will be the only acceptable blending agent.

The only valid alternative practice to blending is to use well-proven wax modifiers as fuel additives. This includes FPPF's Polar Power, Total Power and Biodiesel Winter formula. These chemicals greatly reduce the pour point of diesel fuel and offer a significant operating temperature improvement of up to 150 - 200 F. A fuel heater placed in or near the fuel filter also can provide significant operating advantages in cold weather. The combined use of quality fuel additives and in-filter heaters should allow most operators to use economical # 2 diesel at temperatures less than -150F.

LUBRICITY TESTING -

These issues make it clear that diesel fuel lubricity standards are necessary. A barrier to the new specification has been agreement on a standard test for fuel lubricity. This has been accomplished with the approval of the HFRR/High Frequency Reciprocal Rig) test and an enhanced version of the B.O.C.L.E. (Ball On Cylinder Lubricity Evaluator).

The B.O.C.L.E. test involves pressing a ball bearing against a rotating ring partially immersed in the lubricating fluid; in this case, diesel fuel. Weight is applied on the ball bearing until the lubricating film fails, leaving a scuff mark on the rotating cylinder. An enhanced version of the B.O.C.L.E. test is the B.O.C.L.E. scuffing test, which is more definitive. Initial data has correlated well with actual fuel pump tests.

Injection Equipment Manufacturers and Industry organizations, including the Society of Automotive Engineers (SAE), the American Society for Testing and Materials (ASTM), and the International Standards Organization (ISO), to help define a diesel fuel lubricity standard and a test method that can be used to assess the properties of the proposed low-sulfur fuels.

The latest accepted and preferred test to the B.O.C.L.E. has been developed in England by PCS Instruments, a company comprised for former researchers from the Tribalogy Department at Imperial College, London. It is called the high-frequency raciprocating rig (HFRR) test and because it vibrates one piece of metal against a stationary one with the test fluid in between, it more closely models the action of reciprocating injection pump components.

According to ongoing Industry studies ultra low-sulfur diesel fuels do not exhibit adequate lubricity characteristics. Actual production fuels obtained in recent months have exhibited even poorer lubricity capabilities. This necessitated refiners to add a very limited amount of lubricity at the rack for ultra low sulfur diesel and most of this additional lubricity can be lost in transit as the lubricity agent migrates to the metal surfaces of the fuel transportation system.

However, even the best quality ultra low-sulfur fuels offer varying degrees of lubricity, and testing indicates that virtually all diesel users will experience problems.

A HISTORY OF POTENTIAL PROBLEMS -

The U.S. has been closely observing low-sulfur fuel usage around the world. In Sweden, for instance, strict regulations require sulfur levels no higher than 100 PPM and 10% aromatic fuel. In Canada, low-sulfur diesel fuels have been marketed for several years. Problems with increased wear have been encountered in both countries. Wholesale introduction of the low-sulfur fuel in Sweden had disastrous effects on diesel engine operation and resulted in a crisis situation for Swedish refiners and a European rotary fuel pump manufacturer. Swedish refiners are now using additives to prevent excessive wear in fuel injection systems and their problems are apparently under control. Certain major Canadian refining companies are adding lubricants before delivering fuels to the customer.

At this time, the ASTM, SAE and ISO have agreed that fuel-lubricity enhancement is needed.

FPPF and other fuel injection manufacturers are concerned that the problems experienced in Sweden could be repeated in the U.S. - a regrettable situation since solutions to avoid problems exist today.

In summary, the responsibility rests with diesel equipment end-users to use fuel additives to maintain the reliability of their diesel engines. Consumers can ensure normal reliability and life-expectancy of their diesel fuel systems by individually treating their fuel tanks with quality additives like FPPF's Lubricity Plus Fuel Power, Lubricity 100%, RV/BUS/SUV Formula, Fuel Power and in the Winter: Total Power and Polar Power.