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Testing the cloud point and pour point of petroleum products

What is the cloud point of a lubricant?

The cloud point of a petroleum compound, such as biodiesel or a lubricant, is an index of the lowest temperature below which the least soluble species crystallises into a wax, clouding the liquid. Failure to properly take this property into account when choosing a petroleum product for a certain application can lead to seriously detrimental effects. For example, in fuel oil applications, clouding of fuel at or below the cloud point can cause engine obstruction, filter gumming and piston ring sticking due to the solid wax residue. Therefore, it is essential that engine manufacturers choose the correct products for the conditions created in their systems.

What is the pour point of a lubricant?

The pour point of a petroleum product is the temperature below which it ceases to flow naturally under the effect of gravity. Below the pour point oils lose their flow characteristics, compromising their utility for certain applications such as engine lubrication and contaminant removal. Failure to consider the pour point can lead to reduced or completely failed circulation of oils around a system. In the case of lubricants, for example, this can lead to severe damage as the unlubricated motion of components against each other generates friction and causes surface wear.

Can I perform cloud point and pour point tests with one instrument?

Yes, the Automated Cloud and Pour Point Analyser can perform both cloud and pour point tests. The detachable wireless head components determine which pre-programmed test is performed: the operator simply has to attach the correct wireless head and the instrument automatically senses which test should be conducted.

These detachable units can be purchased separately; the instrument can be purchased and configured to perform one test, then the second wireless head purchased at a later date and the operator is immediately ready to perform the other test as well.

Can I use the Automated Cloud and Pour Point Analyser to comply with ASTM regulations?

Yes, the Automated Cloud and Pour Point Analyser complies with modern ASTM methods. Prior to these standards though, cloud and pour point testing were historically performed manually, using the referee test methods. These involved someone visually observing the oil’s behaviour under different conditions and were some of the oldest ASTM methods ever enacted; ASTM D97, used to test the pour point, was approved in 1927.

Recently, new cloud and pour point test methods and instruments have been developed that offer multiple advantages over traditional approaches, such as greater precision and increased automation. ASTM D5771 and D5950 are two of these methods, which are the test methods for determining the cloud point and pour point of petroleum products as per the optical detection stepped cooling method and the automatic tilt method, respectively.

How are the automated test methods performed for cloud and pour point analysis?

The optical detection stepped cooling method, performed according to ASTM D5571, finds the cloud point by incrementally reducing the temperature of the petroleum sample until wax crystals begin to form. Crystallisation is detected by light sensors in the testing chamber walls, which register the change in the light intensity when opaque wax forms.

The automatic tilt method, performed according to ASTM D5950, finds the pour point by incrementally reducing the temperature of the petroleum sample and tilting it at specific intervals. Once no movements in the liquid are detected after being held in a horizontal position for five seconds, the pour point is recorded.

Operation of the Automated Cloud and Pour Point Analyser is done in five simple steps:
1. Select the appropriate wireless head.
2. Fill the test jar with the sample, install the cork ring and load it into the instrument, placing the head over it.
3. Enter the sample ID, operator name and select a test method.
4. Check the progress of your test using the graph on the test screen
5. View and export your results

How is the Automated Cloud and Pour Point Analyser controlled and does it store my results?

The test methods are all pre-programmed but they can be modified and saved and the operating system is based on a fully functional Windows structure. You can store the sample ID, the operator and the method and you can enter the expected value. This can preset the test parameters to a narrower range, which speeds up the process.

What to do next?

To find out more about the Ciqtek EPR spectroscopy offering, visit SciMed’s web pages for the EPR-W900, EPR200-Plus, EPR200M and the EPR100. Alternatively, to speak to one of SciMed’s team about how you can use the Ciqtek EPR product range to monitor electrode materials and redox mechanisms in real time, contact us below.

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