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Pour Point & Cloud Point


Pour Point 
 
The bunker fuel pour point is the lowest temperature at which a residual fuel can be handled without excessive amounts of wax crystals forming out of solution. If a fuel is below the pour point, wax will begin to separate out which will block filters. Wax will also build up on tank bottoms and on heating coils. When heat is re-applied it can be difficult to get the wax to re-dissolve because of its insulating nature, therefore manual cleaning of tanks becomes necessary. 

 


To avoid the operational difficulties just described, it is necessary to store the fuel at least 10°C above the pour point. The transfer pumps in the fuel system are usually designed to operate at a maximum viscosity of 800 - 1000 cSt. For efficient transfer, the fuel should therefore be heated to the right viscosity. For less viscous fuels, i.e. RMA 10 and RMB 30, the important parameter for handling purposes when tank heating is not fitted is the pour point. 


 
For residual fuels, the typical pour point is less than 10°C, however there are occasional instances of 35 - 40°C. The pour point is a characteristic of the crude processed and can also be affected by the manner in which the fuel is manufactured. The pour point can be simply determined although the result cannot be considered to be absolute, it will at least establish if the fuel has a high pour point.



Cloud Point
 
The bunker fuel cloud point is the temperature at which wax begins to crystallise from a clear distillate. These wax crystals will cause rapid filter blockage. Under ISO 8217 a maximum cloud point temperature of minus 16°C is required for the DMX distillate so that emergency equipment can be started at a very low ambient temperature.



Comment
 
Determination of bunker fuel pour point does not need expensive equipment. Use a thermometer, fuel sample and the nearest refrigerator or ice pack. Low temperature will cause fuel to solidify if not heated continually. The Pour Point test is easy to perform and is included as part of the Kittiwake Power Plant Cabinet.
 
Kittiwake's Cloud Point Detectors / Analysers are automatic devices, used for detecting the temperature at which wax crystals form in a translucent oil sample, causing it to become cloudy in appearance.
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