Fuel Quality and Diesel Injector Deposits

Dynamics of post-injection fuel flow in mini-sac diesel injectors part 1: Admission of external gases and implications for deposit formation

“…Deposits formed on the pushrod needle, armature, and other related components upstream of the injector needle are most likely to originate from components transported in the fuel [25]. A variety of internal injector deposits have been identified to form inside modern diesel injectors.…”

“…Unfortunately, Zinc is indicated in accelerated internal deposition in the form of insoluble zinc salts, and is consequently employed in the CEC F-98-08 injector nozzle coking test [27,28]. Other metals such as Sodium (Na), Calcium (Ca), Potassium (K) and Phosphorous (Ph) are often present in the fuel through exposure to sea water during transportation, or their inclusion in corrosion inhibitors, anti-oxidants, de-icing agents, and salt dryers [22,25]. Iron (Fe) and Chromium (Cr) particles originating from hydro-erosion of the hardened steel comprising the components in the diesel fuel injection system are deposited in the diesel fuel as it makes its way through the high-pressure fuel injection system [29,30].…”

“…Iron (Fe) and Chromium (Cr) particles originating from hydro-erosion of the hardened steel comprising the components in the diesel fuel injection system are deposited in the diesel fuel as it makes its way through the high-pressure fuel injection system [29,30]. These metals are able to react with acids present in additized diesel fuel to form insoluble salt deposits [25]. Acids are ubiquitous in modern commercial diesel fuels, in the form of various carboxylic acids (formed through fuel ageing/pyrolysis/oxidation), and in a variety of diesel fuel additives (forming key components in lubricity and flow improvers, corrosion inhibitors, detergents, surfactants, anti-oxidants etc) [25].…”

“…These metals are able to react with acids present in additized diesel fuel to form insoluble salt deposits [25]. Acids are ubiquitous in modern commercial diesel fuels, in the form of various carboxylic acids (formed through fuel ageing/pyrolysis/oxidation), and in a variety of diesel fuel additives (forming key components in lubricity and flow improvers, corrosion inhibitors, detergents, surfactants, anti-oxidants etc) [25]. Examples include: (1) alkyl and alkenyl succinic acids used as corrosion inhibitors, (2) mono-and di-fatty acids used as lubricity improvers, and (3) polyisobutylene succinimides (PIBSIs) used as deposit control additives (DCAs).…”

“…Metal ions reacting with acids leads to the formation of insoluble salts which deposit inside small-clearance injector surfaces in the form of waxy soaps. Mono-and di-fatty acids are able to react with polyisobutylene succinimides (PIBSIs) to form brown, sticky organic amides and hard, peptide polymer lacquer deposits [25,26]. Stressed and aged diesel fuels can be degraded to produce black, crusty, carbonaceous deposits that are found in fuel tanks, fuel filters, injector nozzle holes and on injector tips.…”