Deposit piston

As a result of this, unbumed fuel can remain in the combustion chamber to be drawn into the crankcase with the oil lubricating the piston cylinder, or it can remain within the upper part of the cylinder to carbonize and form combustion chamber deposits. Piston ring and land groove deposits can also form. 

The second detergent function is to prevent formation of varnishes that come from polymerization of deposits on hot surfaces of the cylinder and the piston. Finally, by adsorption on metallic surfaces, these compounds have anti-corrosion effects. 

Eunctional or hard chromium plating (169,175) is a successfljl way of protecting a variety of industrial devices from wear and friction. The most important examples are cylinder liners and piston rings for internal combustion engines. Eunctional chromium deposits must be appHed to hard substrates, such as steel, and are appHed in a wide variety of thicknesses ranging from 2.5 to 500 ]Am. 

Diesel fuel may contain ash-forming materials in the form of abrasive solids or soluble metallic soaps. These solids cause wear of injection equipment, pistons, piston rings, and liners as well as increasing engine deposits. Ash content is expressed as a percentage of the weight of the original test sample of the fuel when burned to completion m an open container. 

Caterpillar IH2 determines the lubricant effect on ring sticking, ring and cylinder wear, and accumulation of piston deposits. 

Cummins NTC-400 measures crownland and piston deposits, camshaft roller follower pin wear and oil consumption. 

Mack T6 assesses oil oxidation, piston deposits, oil consumption and ring wear. 

In the piston-type compressor the very thin oil thin has to lubricate the cylinder while it is exposed to the heat of the compressed air. Such conditions are highly conducive to oxidation in poor-quality oils, and may result in the formation of gummy deposits that settle in and around the piston-ring grooves and cause the rings to stick, thereby allowing blow-by to develop. 

In oxidizing, oil becomes thicker and it deposits carbon and gummy, resinous substances. These accumulate in the piston-ring grooves of reciprocating compressors and in the slots of vane-type units, and as a result, they restrict free movement of components and allow air leakage to develop. The deposits also settle in and around the valves of piston-type compressors, and prevent proper sealing. 

Modern pump designs also include a means for flushing the piston with solvent behind the pump seal (not shown in Figure 13.4). The solvent for this is drawn in from a separate reservoir and pumped back into this same reservoir. The purpose is to continuously rinse the piston free of mobile phase residue such that abrasive solute crystals resulting from a mobile phase that has dried out on the piston will not deposit there. These solutes, such as the salts dissolved in the buffered mobile phases used in ion exchange chromatography, may otherwise crystallize on the piston and then damage the piston or the pump seal when the piston moves back and forth. Mobile phases that contain such solutes must be flushed from the system after use so that there is also no crystallization on the front side of the seal. 

Fig. 3.2(b) Puff-—Crankshaft rotating, piston draws air through burning cigarette depositing particulate phase on Cambridge filter. Vapour-phase passes through to piston. 

Whenever new engines bum fuel, a certain amount of carbonaceous material builds up on the walls of the combustion chamber and the piston crown. These deposits act to increase the compression ratio and temperature of the cylinder environment. After about 10,000 miles, most vehicles accumulate enough deposit so that their... 

In marine fuel applications, injector deposits and the corrosive wear of piston rings have been linked to fuel sulfur and sulfur bearing acid formation. 

Together, water and SO can combine to form sulfur-bearing acids. These acids can accumulate to initiate corrosive wear, oxidation of lubricating oil, and the formation of piston lacquer deposits within the combustion chamber. Engine deposits can result in operability problems such as preignition knock, dieseling, and wear. 

Good combustion is characterized by a flame burning uniformly across the piston head. Deposits and poor-quality fuel can interfere with the movement of the flame across the combustion chamber. Rough running can result. 

The elemental composition of unknown materials such as engine deposits can be determined qualitatively and the information used to develop dissolution methods prior to analysis by inductively coupled plasma atomic emission spectroscopy (ICPAES). Alternatively, a semi-quantitative analysis can be provided by XRF alone, especially important when only a limited quantity of sample is available and needed for subsequent tests. The deposit does not even have to be removed from the piston since large objects can be placed directly inside an EDXRF spectrometer. 

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