Innovations in Cloud and Pour Point Testing Methods

by Raj Shah, Alexandra Przyborowski, Nathan Aragon

Over the last several years, there has been a multitude of advancements made in efforts to improve the performance of various petroleum products through Cloud and Pour Point Testing. Cloud and Pour Point come into play when determining the low-temperature behavior of a product as well as assessing whether a product will be able to maintain performance under theorized temperature conditions¹. While cloud and pour points are often mentioned together it is important to note that they measure two different parameters. Cloud Point is the lowest temperature at which a liquid specimen becomes cloudy and the components within start to precipitate hydrocarbon crystals upon cooling². Pour Point measures the lowest temperature at which a product can continue to flow, without stirring³. Both testing methods are crucial for effective and error-free analysis’ that will help determine the lowest temperature for optimal performance and storage temperatures of the petroleum product.

Unrefined petroleum, also called crude oil, is the largest U.S. energy source⁴ to date. Gasoline is the most consumed petroleum product, but petroleum encompassed a wide variety of oils and fuels that are important for many essential processes. Whether it be heating a building, producing electricity, or starting an engine, petroleum products require proper testing for optimal performance. Cloud and Pour Point Testing allow for an adequate reference for determining whether certain oil products will succeed in different environmental conditions concerning temperature. Testing equipment being used today now has the capability to indicate the lowest temperature of utility for all petroleum products, minimizing human error and maximizing success.

Koehler Instrument Company, Inc., has developed the K77000 Automatic Cloud and Pour Point Analyzer⁵, which comprises an interchangeable wireless head for the use of both Cloud and Pour Point testing. The analyzer has a full-color touch surface interface that allows for different inputs and produces accurate and easy-to-read results. The steps necessary to prepare for a test are as follows; first, fit the cork ring around the test jar and pour the sample into the test jar; next, load the test jar into the test sleeve and secure the Pour Point, or Cloud Point, head to the instrument. Once the parameters are noted and the start button is pressed, the test will begin. The machine records data every minute until preheating is complete, which is then followed by the cooling process. The cloud/pour point, testing begins once this happens⁶. When the previously set temperature has been reached, the instrument will begin conducting the cloud/pour determinations and recording the results which will be later stored into the analyzer for viewing. This analyzer allows for error-free testing that eliminates the need for constant monitoring as once was necessary for prior machinery performed with manual methods. Data collection through the use of such instrumentation is necessary for appraising flow properties at low temperatures. Having this knowledge can avoid the many potential mistakes made in engineering and manufacturing that can cause bigger catastrophes.

A real-world application that everyone is familiar with is biodiesel and its usage in fuel compression-ignition engines. Biodiesel is a form of diesel fuel derived from plants or animals which consists of long-chain fatty acid esters. In cold temperatures it is common for fuels to thicken and not flow properly, affecting the performance of the system. Data shows⁷ that in petroleum diesel there is a 20-degree difference between cloud point and pour point, but in biodiesel, the difference may only be a few degrees. This is why it is necessary and crucial to test for cloud point and pour point to determine the actual temperature the fuel can be used in. For the cloud point test, the temperature at which the liquid fuel begins to change from a single-phase to a two-phase system is obtained. For the pour point test, the lowest temperature at which there is still movement of the fuel when the container is tipped is tested for. Both measurements are collected to avoid clogging of fuel filters, freeze jamming in machine parts, and complete failure of fluid flow in systems that can result in downtime of the equipment and costly repairs.

Automatic Cloud and Pour (C&P) Point Analyzers are much more efficient than manual methods that are still being used in laboratories. Measuring the C&P point of petroleum products through manual methods requires an individual to be monitoring the sample at each stage of the test. In the manual method, technicians pour a test sample into a test jar and add a cork that is holding a test thermometer. They then place this test jar into a constant temperature cooling bath. Someone must observe and control the experiment the whole time, which may result in inaccurate pour and cloud point determinations because the thermal history has not been canceled by prolonged thermal treatment. Also, manual methods require a separate test for both cloud and pour point. However, using Automatic C&P Analyzers allows for a quicker, error-free, and more innovative approach to obtaining results. Automatic C&P Analyzers also have the capability of running both tests with the same instrument, just with specific wireless heads, saving time which is not a possibility when testing C&P manually.

 Cloud and Pour points are related to low-temperature characteristics of fuel and inform the users of the behavior of fuels at low temperatures. It is an essential guide to educate users on how to safely handle and apply different types of petroleum products⁸. These two important physical properties are used to account for weather extremities and how to utilize different fuels due to naturally occurring conditions. Automatic Cloud and Pour Point Analyzers allow for successful innovations and engines to be introduced to the general public. A critical specification needed for the correct operation of fuel systems, lubricant oil systems, and petroleum operations⁹ all comes down to Cloud and Pour Point.

About the authors: Nathan Aragon is a student of Chemical Engineering at SUNY, Stony Brook University. Alexandra Przyborowski is an intern with Koehler Instrument Company. Raj Shah is a Director at Koehler Instrument Company in New York, where he has worked for the last 25 years. He is an elected Fellow by his peers at IChemE, CMI, STLE, AIC, NLGI, INSTMC, The Energy Institute and The Royal Society of Chemistry.

References 

1. Irjes and Irjes, “Determination of Cloud And Pour Point of Various Petroleum Products,” Issuu. [Online]. Available: https://issuu.com/irjes/docs/a6910104. [Accessed: 04-Mar-2021].
2. “Cloud and Pour Point Analyser,” Croda. [Online]. Available: https://www.crodalubricants.com/en-gb/discovery-zone/how-we-test-our-products/pour-point-cloud-point#:~:text=Cloud%20and%20Pour%20Point%20Analyser&text=Pour%20point%20is%20the%20lowest,under%20test%20precipitate%20on%20cooling.
3. “Cloud and Pour Point,” Lazar Scientific Inc. [Online]. Available: https://lazarsci.com/cloud-point-and-pour-point/. [Accessed: 04-Mar-2021].
4. “U.S. Energy Information Administration - EIA - Independent Statistics and Analysis,” Use of oil - U.S. Energy Information Administration (EIA). [Online]. Available: https://www.eia.gov/energyexplained/oil-and-petroleum-products/use-of-oil.php. [Accessed: 04-Mar-2021].
5. “Products,” Koehler Instrument Company Inc. [Online]. Available: https://koehlerinstrument.com/products/cloud-and-pour-point-test-equipment/. [Accessed: 04-Mar-2021].
6. ASTM D5771 “Standard Test Method for Cloud Point of Petroleum Products (Optical Detection Stepped Cooling Method)” (ASTM International). ASTM D5950 “Standard Test Method for Pour Point of Petroleum Products (Automatic Tilt Method)” (ASTM International)
7. Farm-Energy, “Biodiesel Cloud Point and Cold Weather Issues,” Farm Energy, 12-Apr-2019. [Online]. Available: https://farm-energy.extension.org/biodiesel-cloud-point-and-cold-weather-issues/. [Accessed: 04-Mar-2021].
8. A. T. Editor, “What is cloud point and pour point,” Polytechnic Hub, 10-Jun-2018. [Online]. Available: https://www.polytechnichub.com/cloud-point-pour-point/. [Accessed: 04-Mar-2021].
9. Koehler Instrument Company, INC., Automatic Cloud and Pour Point Analyzer. Koehler Instrument Company, Inc., Madrid.

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