Lubrication, Cooling, and Working-Fluid Chemistry
Core concepts
Know the roles of lubrication: separating surfaces, removing heat, and carrying debris to filters. Understand viscosity grade, oil oxidation, foaming, and the significance of water and particulate contamination. Candidates must know cooling systems: closed-loop demineralized water, cooling towers, and the consequences of scaling, fouling, and corrosion. For steam chemistry, understand pH control, dissolved oxygen, conductivity, silica, and cation conductivity as an early contaminant indicator. For gas turbines, know fuel quality and air filtration effects.
Traps
Questions often confuse total conductivity with cation conductivity; cation conductivity reveals acidic contamination even when pH seems acceptable. Another trap is adding raw water to a demineralized loop. Remember that low oil pressure and high oil temperature are different failure modes with different trip responses.
Worked rule of thumb
For steam chemistry, target slightly alkaline conditions, typically pH around 9 to 9.5 for many drum units, to limit corrosion, and watch cation conductivity as the sensitive tripwire for condenser leakage. A rising cation conductivity with stable pH suggests anionic contamination, often a tube leak.
Exam focus
Be able to link a chemistry trend to its likely source and to the equipment at risk.