Cloud Point Testing
The cloud point is the temperature at which wax crystals begin to appear in a liquid. The cloud point is typically higher than the pour point. When dealing with lubricating oils, the cloud point is a temperature reading at which components that tend to solidify start separating from the oil and begin crystallizing. The presence of wax crystals in fuel oil tends to thicken the oil and can jam fuel filters and injectors within the engines. The cloud point basically determines whether or not the oil will possibly jam filters or small orifices at colder temperatures. The cloud point tends to get confused with the freezing point from time to time. The freezing point differs because it is an estimate of minimum handling and storage temperatures. Unlike the cloud point, the freezing point has little value for lubricating oils, because it does not concentrate on the samples purity. Lubricating oil cloud point testing is important, especially for oils funneling through restricted orifices.