Zeons Corporation (ZEON)

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Biodiesel Test Descriptions

As biodiesel expands to be a viable alternative fuel to traditional petroleum based fuels, many forward-looking companies are starting to produce and distribute it. Quality and consistency of the finished product is of major concern because of the variety of production techniques and feedstocks. Here is a selection of key tests involved:

Free & Total Glycerin: Perhaps the most important test for biodiesel is the measure of glycerin content. The key reaction in biodiesel production, transesterification, involves converting oils and fats to fatty acid methyl esters (FAME). Glycerin is the major byproduct and is higher in density and more polar than the FAME. Glycerin may be present in free form, and bonded, (mono, di and triglycerides). Measurement of both is necessary to determine how the conversion reaction proceeded.

For producers: high glycerin content indicates the reaction has not proceeded to completion, or your driver and /or catalyst is weak (wrong concentrations).
For Distributors/End users: high glycerin may separate out in storage, plugging pumps and filters. It can also contribute to dirty injectors, thus causing poor combustion conditions.

Phosphorus, Potassium, Sodium, Calcium, Magnesium by Spectrometric Analysis: Technique for detecting and quantifying metallic elements in a fuel resulting from, contamination, soap formation or additives. The fuel sample is energized to make elements emit or absorb a quantifiable amount of energy, which indicates the element's concentration in the fuel.

For Distributors/End users: Phosphorus can poison catalytic converters, rendering them ineffective. It can also create hard deposits on piston crowns, valves and injectors, affecting the engine performance and reliability. Sodium and Potassium may form abrasive solids or metallic soaps which may cause abrasion and filter plugging. Calcium and Magnesium metals clog particulate traps which will be used with ULSD.

Cloud and Pour Point: Defined as the lowest temperature at which wax crystals begin to form in the fuel. Pour point is the temperature at which the fuel ceases to flow.

For Producers/Blenders: B100 has a cloud and pour point of 32F and 25F respectively. High values may indicate additives are not present to lower the cloud and pour, or not present in the desirable concentrations. Alternatively, the blending with #1 or #2 diesels needs to be increased.

Cold Soak Filtration Analysis: The time in seconds it takes for cold soaked biodiesel to pass through two 0.8 micron filters and the amount of particulate matter expressed in mg/l collected on the filter.

For Producers/Blenders: Poor filtration can be related to choice of feedstock, as well as incomplete glycerin removal during processing. It may also indicate the B100 product was subjected to low temperatures (below pour point). It is not sufficient to warm to ambient- product must be heated to 100F to liquefy all molecules present.
For Distributors/End users: High filtration times indicate the potential for fuel filter plugging. In freezing climates, consider heat trace on storage tanks, blend and piping equipment. End users may look to install heated filter housings.

Viscosity: The resistance of a fluid to flow. Fuels must have suitable flow characteristics to insure that an adequate supply reaches injectors, at different operating temperatures.
For Producers/Blenders: Verify that the transesterification reaction has proceeded properly. The glycerin content may be elevated and flash point high. Reprocess the batch.

For Distributors/End users: High viscosity can cause fuel flow problems, and lead to stall out, or fuel pump failure.

Total Acid Number: A titration method designed to indicate the relative acidity in a feedstock. It is a particularly good indicator of the level of free fatty acids (FFA) present in biodiesel, as well as the presence of process acids and degradation by products.

For Producers/Blenders: High Acid values on your feedstock indicates unrefined or poorly refined product. Typical problems would be poor process control, such as methanol carryover, when converting the oils and fats to FAME fuel.
For Distributors/End users: High Acid number fuel can have a strong solvency effect on rubber seals and hoses in the engine, thereby causing premature failure. It may also leave deposits, which can clog the fuel filter or drop fuel pressure.

Flash Point: The lowest temperature at which the vapor of a combustible liquid can be made to ignite momentarily in air. The flash point of a fuel infers to the ignitability of the fuel.
For Producers/Blenders: A low flash point can indicate residual methanol remaining from the conversion process. A high flash point can mean the reaction has not proceeded to completion.

For Distributors/End users: A low flashpoint in biodiesel can result in premature ignition, causing irregular timing, excessive fuel blow by into the crankcase oil, and excessive emissions. A high flash point can lead to poor ignition, resulting in inconsistent firing, and variable engine performance. It can also indicate potential clogging of fuel lines, filters and injector clogging in cold climates.

Water & Sediment: Though water is always present in fuel, it is important to control its content. Bottoms sediment and water is where the biodiesel is centrifuged vigorously to separate out free water and any trace sediment present in the fuel. Water can be detected visually if gross contamination is present (cloudy appearance). The Karl Fischer method is used for moisture contamination down to levels of 10 ppm (.001%). BTS recommends the Karl Fischer method.

For Producers/Blenders: Excessive water may indicate water wash/removal process is not performed correctly.
For Distributors/End users: Improper storage may be the reason, and poor ignition, filter clogging, fuel pump problems can be the result. If sediment is present, replace the fuel filter cartridges.

Sulfur: A common contaminant in fuel. Sulfur in fuel leads to sulfur oxides being produced as exhaust gases, which can harm the environment, and as acids in the engine crankcase, which will attack the lubricant. Biodiesel will have little to no sulfur present, making it a great emissions reduction fuel. Some sulfur is desirable in refined petroleum based diesel as it provides lubricity for the fuel pump. Biodiesel fulfills that function with the free fatty acids present.

For Producers: If sulfur is present, check the source of the feedstock to make sure it is not hydrocarbon based.
For Distributors/End users: High sulfur leads to emissions problems.

Distillation: A method for determining the full range of volatility characteristics of a hydrocarbon liquid by progressively boiling off a sample under controlled heating. Different methods are available for distillation: atmospheric, vacuum, and simulated.
Biodiesel is fundamentally different than petroleum based diesel, and it is especially evident with distillation. Biodiesel has a fairly homogenous consistency of straight chain hydrocarbons, all with 16 to 18 carbons. Consequently it exhibits a boiling point rather than a distillation curve.

For Producers: High distillation values may indicate the conversion reaction has not gone to completion, (flash point may also be high). Low values indicate methanol carryover.
For Users: High distillation values lead to poor starting, especially in cold weather; low values can lead to poor timing and seal material failure.


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