|
|
||
|
Testing your waste oil for water content - The Crackle Test Update: It was brought to my attention that the oil industry-standard crackle test uses a different method than described below. However, this test involves being able to monitor and consistently maintain a surface temperature of 320 degrees Fahrenheit without any oil in the pan. Since that can be difficult and may require an expensive "temp gun" I will continue to test and adjust the temperatures of my test with different emulsions of oil and water. Therefore, be warned that the test below is a "DRAFT" and may not be a good indicator of water in oil. Now that you have potential sources for vegetable oil you need to gather samples of the oil and test it for quality and water content. Water in veggie oil fuel is one of the biggest problems that greasers that don't follow this lesson have with using waste vegetable oil as fuel. If you attempt to heat waste oil that has high water content before filtering, you could burn the house down if you heat the oil at or near the boiling point of water! Another myth in the grease community is that greasers use is to only suck the oil from the middle of the barrel. By doing this they believe they can avoid any water that might be emulsified in the oil. Unfortunately, this is not true. Chances are that the oil has not had enough time to settle since the last batch was dumped in the barrel. In some environments, the water and oil can stay emulsified indefinitely until the mixture is heated to at least 212 degrees Fahrenheit at sea level and the oil is boiled off. (some greasers will introduce a vacuum to the oil container to reduce the temperature at which the water will boil off.) The best method that I have found for checking oil for water content is described below. When I identify a new oil source, I always perform the "crackle test" on the sample oil before accepting an agreement to pick up the customer's oil. Once I've established that the oil source uses acceptable methods of transferring and storing the waste oil, I do not test the oil for each pickup unless it looks different or I expect that something has changed in the way they store the oil. Performing the "Crackle Test" In order to test a new oil source for water, a small sample is taken from the oil supply, heated to 212 degrees Fahrenheit and monitored for bubbling or popping as it approaches the boiling point of water. This could be performed at a lower temperature by introducing a vacuum but I prefer the "Hot Plate Crackle Test" procedure for my testing. Preparing the area In order to avoid a dangerous fire hazard or a disgruntled spouse, I recommend setting up a test area in the garage or in the backyard with the right tools and proper safety precaustions. I prefer a table made from a non-combustible material using an electric hot plate, old pan, candy thermometer and a fire extinguisher.
I purchased the electric hot plate from a local variety store for less than US$10. They can also be had at big box retailers such as Target and Walmart stores. In the pictures above, I'm using an old empty steel barrel as a non-combustible table. Warning! Do not use a barrel full of combustible liquids or fuel. Also, I would recommend releasing any internal pressure by unscrewing the bung cap and replacing it before heating anything on top. The fully charged fire extinguisher in picture on the right is the most important item in the "Crackle Test."
Make sure that the candy thermometer is attached to the side of the pan and adjusted so the bottom of the thermometer is off the bottom of the pan but will be submerged in the oil as it is heating. We're looking for an accurate temperature reading of the oil and not the surface of the pan. From a small sample container of waste oil, pour enough oil to cover the bottom of the pan and submerge the bottom tip of the candy thermometer in the oil. Avoid filling the container up even to the halfway point. Since you are not familiar with the water content of this oil, you don't want to be surprised with a large sample of water-laced oil when the pan heats up and the water starts boiling off!
Notice in the picture below how much oil is in the pan. Also notice that I am using a small sauce pan that allows me to get a decent depth to the oil sample without having a large volume of oil to create a possible hazard.
Once you make sure that the area is clear and you are familiar with quick operation of your fire extinguisher, plug in the hot plate and turn it up to approximately medium high. Start watching the thermometer carefully while familiarizing yourself with the points on the thermometer indicating that the oil will boil soon if there is water. (a little over 210 degrees Fahrenheit)
The oil above is approaching 175 degrees Fahrenheit. Start getting prepared for possible water boiling as you are probably within 40 degrees of water's boiling point.
The oil is now at the boiling temperature of water and no popping or cracking! However, if you hear some occasional popping and cracking you may have some moisture in the oil or in suspended food particles. This can be remedied very easily by a basic dewatering and filtering process. If your oil reaches a rolling boil before 200 degrees Fahrenheit, you know you are dealing with an oil water emulsion. If this is your result, consider picking another source for the oil and/or talk with the supplier to see if there is anything they can do to help reduce the water in the oil. Some simple remedies include training the fryer operator to keep water and cleaning solution separate from the oil or sealing the storage container before leaving it outside in the elements.
Once the oil has reached temperature and the test is complete, carefully turn off the hot plate and remove the pan from the burner and place it on a safe, cool location that will not be scorched by the heat. An electric hot plate takes a while to cool. If you leave the pan on the burner, it will continue to rise in temperature. If your oil has water, you could end up with a dangerous condition. By removing the pan from the heat immediately, the oil will begin cooling immediately as well. As stated earlier in another biofuel lesson, one of the quickest ways to trash a diesel engine no matter what fuel you use is to introduce fuel contaminated with water into the fuel system. It will corrode the inside of the injection pump and injectors. If sprayed into the cylinder, it can cause imcomplete combustion or other more severe problems. Waste Vegetable Oil (WVO) can be dewatered by heating it before use. Water boils at 212 degrees Fahrenheit... a much lower boiling point than oil. By heating the WVO to 250 degrees for at least 15-20 minutes, all water will turn to steam and be released from the WVO. Some other processors prefer to heat the oil to 212 degrees and let it hold steady until all water is boiled off. Once the temperate starts approaching 230 degrees F. the oil will be free of water. Most diesel engines also have a fuel/water separator installed inline between the injectors and the fuel tank to help prevent introduction of water into the injection pump and combustion chamber. If your vehicle has a separator, make sure you drain the water from the device periodically. However, do not count on a fuel/water separator as your only line of defense from an oil/water emulsion and a damaged engine! (if you arrived here from Lesson 6, click here to return) DRAFT
|
||
