What is Cummins' position on the use of Water-Emulsified Diesel Fuel?
Subject: Cummins Position on the use of Water-Emulsified Diesel Fuel Background The water-emulsified diesel fuel includes the additive, a blending unit and the blended fuel. The fuel is made up of (2 to 3%) additive, needed as an emulsion enabler, corrosion inhibitor and lubricity improver, about 18% water, and about 80% #2 diesel. There may also be seasonal changes, such as the addition of methanol during the winter months. Testing of this blend has taken place with a variety of engines, including Cummins engines. There are multiple venders currently selling water-emulsified diesel to local route fleets for on and off highway use. Fuel Characteristics Pour point and cloud point are not stated in the literature but it is expected that they can be tailored to the requirements of specific locations. Flash point can vary from 174 degrees F in the summer to 104 degrees F in the winter with 5. 6% methanol (#2 diesel is 126 degrees F min. ). The lower winter fuel flash point of 104 degrees F can present fuel handling and storage concerns compared to #2 diesel fuel. Note that Cummins does not allow any use of alcohol in diesel fuel due to concern of fire hazard. Otherwise, the fuel can be handled, stored and dispensed in a similar manner to diesel fuel. Emissions Emissions results with water-emulsified diesel fuel show a reduction in particulates of 25-60%, a reduction of NOx from 8-30% and Hydrocarbon (HC) by 25%. Carbon Monoxide (CO) tends to increase by 5%. This type of fuel is verified by EPA and some state agencies as an emissions reduction technology. Cummins does not certify engines based on this fuel. Cummins does not guarantee any emissions benefits should this fuel be used. Performance and Durability Issues Due to the lower energy content (~80% of #2 diesel), at least a 15% power reduction is to be expected, together with a 15% increase in fuel usage for the same duty cycle. The reduced energy content may also require an idle governor change to prevent stalling. In terms of fuel system durability, the water-emulsified diesel fuel has passed the 500 hr Stanadyne bench test without any lubricity impact compared to diesel, and has also passed the Cummins L10 injector deposits test. Customer experience is mixed with water-emulsified diesel fuel. Some customers operating engines with water-emulsified diesel fuel report no issues after extensive operation. Others, including customers with current and older model midrange and heavy duty Cummins engines, report fuel system failures at low mileage/hours. Analysis to date confirms failures of fuel system components including injectors on heavy duty Cummins engines and abnormally worn governors, pistons, diaphragms, and plungers on Bosch and Cummins midrange fuel injection pumps and injectors. Fuel System Vehicle Issues and Storage It should be noted that since water is in an emulsified state with diesel fuel, the conductivity sensors used to detect water in fuel such as the one offered by Fleetguard, will not function. The use instructions of some vendors of water-emulsified diesel fuel specify the removal of the fuel water separator, which violates Cummins installation requirements. Cummins has seen evidence of water separation from the emulsified fuel. Free and emulsified water inevitably damages fuel system components without the protection of the water separator, which would not be compensated under Cummins material or workmanship warranty. The use of a surfactant in the emulsifier has the potential to strip the fuel tank and lines of existing deposits causing fuel filter plugging. Fuel filters should be monitored closely during initial use. The fuel cannot remain static for more than a month in storage or vehicle tanks. Engines operating on this type of fuel need to be operated at least 15 minutes every 30 days and the storage tanks need circulation pumps for daily or weekly agitation. Failures resulting from storage issues have been reported in applications such as standby gen-sets. Warranty and the use of water-emulsified diesel in Cummins Engines Cummins neither approves nor disapproves of the use of water-emulsified diesel fuel. The use of water-emulsified diesel fuel or any other certified fuel additive does not void the Cummins material and workmanship warranty. However, failures determined by Cummins to be caused by water-emulsified diesel fuel or other fuel additives are NOT covered under Cummins engine warranty. Some fuel suppliers provide a comprehensive warranty for fuel system failures caused by water-emulsified diesel fuel and other fuel additives. Customers are encouraged to contact their fuel supplier to determine their warranty provisions for fuel related failures