Icon’s Cold-Flow Property Analysers

As the world shifts to safer and more sustainable fuels, we need reliable ways to measure and analyse their key properties. The cold-flow properties of fuels are one of these key properties. They indicate the low-temperature operability of a fuel and help determine its cold-weather performance.

What are the key cold-flow measurements?

The key cold-flow property measurements are the cloud point, pour point, freeze point, and cold filter plugging point (CFPP).

The cloud point is the temperature at which wax crystals first appear as the fuel is cooled. This is a key quality parameter for diesel and biodiesel fuels, indicating the temperature at which the fuel will start to block fuel filters and injectors.

For the pour point, the measurement temperature is the point just before the fuel no longer flows. When the fuel no longer flows, this temperature is the no-flow point. The pour point is a particularly significant measurement for fuel oils.

The CFPP is the lowest temperature at which fuel still passes through a standardised filtration device. This indicates the lowest temperature at which a fuel will flow through an engine filter or fuel system. The CFPP is another key property for diesel fuels, and is particularly important for biodiesels.

Finally, the freeze point is the temperature at which the last crystal (formed during cooling) disappears. This property is used for aviation jet fuel standards and testing, ensuring flight safety.

What is the difference between the freeze point and cloud point?

The freeze point and the cloud point can sound very similar. However, one key difference between cloud point and freeze point measurements is their application. The cloud point is measured to determine cold-weather performance for diesel fuels, while the freeze point is a key standard measurement for aviation jet fuel. The freeze point will always be higher than the cloud point, as it is reached when all wax crystals have completely disappeared, rather than when they first appear. This is important to guarantee that no ice crystals will form in the fuel system during flight.

How are these properties measured?

The Icon Cloud Point analyser follows the ASTM test methods D2500 and D5771/2/3. A small amount of the sample is trapped in the measuring cell and then cooled at a controlled rate. The cooling process continues until wax crystals are detected by the analyser – this is recorded as the cloud point.

The ASTM methods relevant to the pour point are ASTM D97, D5853, D5949, D5985, and D7346. In the Icon Pour Point analyser, a small volume of sample is trapped in a measuring cell and cooled at a controlled rate. At pre-set temperature intervals, the sample is pressure-pulsed by a stepper-motor-driven piston cylinder. The cooling continues until the sample is no longer moving – this is recorded as the no-flow point, with the corresponding pour point also reported.

The standard test method for CFPP measurements is ASTM D6371. The Icon CFPP analyser follows this test method, with the sample cooled and drawn through a standardized wire mesh filter into a pipette, under a controlled vacuum. This process is repeated, at intervals of 1°C below the initial temperature, until the sample flow is stopped or slowed down to the extent that it takes more than 60 seconds to fill the pipette.

For determining the freeze point, the relevant ASTM methods are D2386, D5972, and D7153. The Icon Freeze Point analyser follows the same method as the Cloud Point analyser, until the cloud point has been found. The sample is then allowed to warm up again until the ‘cloud’ disappears, and the freeze point is reached.

Icon’s Suite of Cold Properties Analysers

Incorporating process analysers to measure the cold flow properties of your fuels allows the refinery to reduce the use of expensive additives and optimise operating conditions. Icon Scientific have a full ecosystem of cold-flow property analysers available to our customers. This includes our Cloud Point, Pour Point, CFPP, and Freeze Point analysers.

All of Icon’s cold-flow property analysers are designed to be low or zero-maintenance, and boast outstanding repeatability, reliability, and cooling performance.

Our newest addition – the CFPP analyser – has revolutionised CFPP measurement, benefitting from Icon’s unique cryo-cooling technology, and improved reliability and accuracy.

The Icon Cloud Point, Pour Point, and Freeze Point analysers all incorporate a vacuum-insulated measuring cell, which improves reliability and cooling performance, as well as eliminating condensation, ice formation, and the effects of stray light.

The optical detector arrangement used by Icon's Cloud Point and Freeze Point analysers gives outstanding repeatability, providing excellent immunity to dissolved water in the sample and to any changes in sample opacity and colour.

The Icon Freeze Point analyser also benefits from Icon’s cryo-cooling technology, to reach lower temperatures without an external chiller unit. The Freeze Point analyser is also capable of low-temperature cloud point and pour point measurements, bringing this advanced cooling technology to all cold-flow applications.

To find out more about the best analysers for your application, get in touch with your local distributor or the Icon team.