Injection pump sticking

In recent years, the concern over fuel lubricity has led to the use of a high concentration of corrosion inhibitors to improve diesel fuel lubricity performance. The film formed on the metal surface by fatty acid type corrosion inhibitors improves fuel lubricity. However, the result of this overtreatment may lead to sticking of injection pump parts. 

Fuel stability is an indication of the sediment- and gum-forming tendency of fuel. Gums and sediment can cause filter plugging and combustion chamber deposits and result in sticking of pumping and injection system components. 

Most thermoplastics processing involves screw machines, whether for extrusion (pipes, film, cables, etc.), blow molding (bottles, fuel tanks, etc.), or injection molding (from cocktail sticks to car bumpers). The processes in all cases involve a powder or pellet raw material being conveyed, melted, and pumped through a die or injected into a mold. 

Stick-slip motion in syringes is defined as the uneven, jerky motion of the stopper which results when the syringe pump fails to overcome the fiiction between the syringe plunger and syringe barrel. This uneven motion results in fluctuating flow rates, in the worst case alternating between bolus injection and periods of no m cant flow (see Row 3 in Table I). (157-159). 

Sample injection depends on two parameters the available equipment and the percent of acetonitrile required to maintain solubility The easiest way to load large volumes of sample onto a reverse-phase HPLC column is to load the sample off the HPLC using a small high-pressure pump, such as the Eldex Model B-IOO-S. (We do not recommend using the HPLC pumps for this purpose because of the possibility of precipitation in the pump.) If the sample is in <10 acetonitrile, it will stick at the top of the column. If such a pump is unavailable, purchase a large loop, preferably 5 or 10 mL. 

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