Common use of VISCOSITY Clause in Contracts

VISCOSITY. The viscosity of fuel is a measure of its resistance to flow. It is important in the fuel auxiliary equipment since it determines pumping temperature, atomizing temperature and oil pump pressure. In order to obtain proper operation of the gas turbine, the maximum viscosity at the fuel nozzles must not exceed 10 centistokes for pressure atomizing or low-pressure air-atomization fuel systems, and 20 centistokes for high-pressure air-atomizing systems. When these limits are exceeded, poor ignition characteristics, smoking, unsatisfactory combustor exit temperature distribution, lowered combustion efficiency or formation of carbon may occur. In most cases, fuel heating must be employed to insure that these viscosity limits at the fuel nozzle are met under all ambient conditions. In all cases the fuel at initial light-off must be at or below 10 cSt viscosity. Minimum viscosity limits are imposed to safeguard the high pressure fuel pump, which depends on the lubricating qualities of the fuel for satisfactory operation. It should be noted that naphtha fuel can have a minimum viscosity as low as 0.5 cSt at 100(Degree)F (37.8 (Degree)C). Special pumps may be required for viscosities below 1.8 cSt at 100(Degree) F.