Cloud point, Pour point, CFPP, Channel point (60ml) – This is the point at which a fuel or low temperature lubricant form a wax causing clouding and eventually stop pouring. The cloud point is the point at which the fluid begins to crystallise. The pour point is considered the point 3OC above the temperature at which the fluid did not pour for 5 seconds when the test tube is tipped on its side. The channel point is considered the point at which a channel can be formed in a lubricating fluid and it does not instantly fill in the gap behind an object passing through it. A CFPP (Cold-Filter Plugging Point) is used on fuels where fuel is passed through a special filter at low temperature eventually causing it to block (Plugging Point) – this is used in conjunction with a cloud point to determine the temperature at which a fuel could possibly begin to cause filter blockages.
Tested On: Predominantly fuels, but any low viscosity fluid can be tested.
Diagnostic significance & Typical Diagnostic limit: On certain fuels there are legislative limits used around the world for fuels depending on climate conditions. In lubricating systems, a cloud, pour or channel point value higher than the lowest temperature the machinery will be operating means the fluid may:
- Block filters with wax deposits (primarily on fuels)
- Be difficult or impossible to pump fuels or lubricants
- Result in wear as the points where a channel in the fluid is left (e.g. gear teeth passing through the lubricant) will have direct metal to metal contact.