R99 renewable diesel holds much less dissolved water than FAME biodiesel. Mixing these fuels changes how the finished blend handles water, cold temperatures, and storage.

Commercially formulated blends can perform well when they meet fuel specifications and engine requirements. However, mixing unknown fuels in a storage tank can create an unpredictable product—and blending should never be used as a substitute for removing water.

R99 and FAME Are Different Fuels

R99 renewable diesel is a hydrocarbon fuel commonly manufactured by hydrotreating renewable feedstocks. Its chemistry resembles petroleum diesel.

FAME—fatty acid methyl esters—is conventional biodiesel. It has a different chemical structure and is commonly sold in blends such as B5 or B20. B20 contains 20% FAME biodiesel; the remaining portion can include petroleum diesel or renewable diesel.

The U.S. Department of Energy distinguishes renewable diesel, which meets ASTM D975, from biodiesel blendstock, which meets ASTM D6751. The finished blend must meet the applicable specification.

Which Fuel Holds More Water?

FAME holds substantially more dissolved water than R99 at the same temperature. As FAME content increases, the blend generally gains the ability to keep more water dissolved.

One NREL study measured water-saturation values of approximately 85 ppm for the tested renewable diesel and 1,567 ppm for the tested B100 FAME. These are examples from specific samples, not universal limits. Fuel composition and temperature affect the actual saturation point.

Greater water-holding capacity does not mean better fuel quality. It means more water can remain present without forming a visible layer.

Clear Fuel Can Still Contain Water

Water occurs in fuel in three forms:

• Dissolved water: Water distributed at the molecular level. The fuel may look clear.
• Suspended or emulsified water: Small droplets dispersed through the fuel, sometimes producing haze.
• Free water: Separated water that typically collects at the tank bottom.

A Karl Fischer test measures water in the tested sample. It does not, by itself, identify how much was dissolved and how much was present as droplets. Representative sampling is essential.

For example, 225 ppm by weight equals 0.0225% water. That result alone does not establish the FAME percentage, prove that all water is dissolved, or determine whether the fuel meets every applicable requirement.

Why Avoid Uncontrolled Blending?

1. Water Can Separate After Mixing

When a FAME-containing fuel is diluted with R99, the resulting blend may hold less dissolved water than the original fuel. If the water content exceeds the new blend’s saturation limit, some water can separate into droplets.

Cooling can also reduce water solubility. Fuel that appears clear during delivery may develop water haze or separated water after conditions change.

This separation is not inevitable. It depends on the starting water content, temperature, and final composition.

2. Adding FAME Does Not Remove Water

Adding FAME may allow more water to remain dissolved. The fuel could appear clearer while still containing the same water.

Making water less visible is not water removal. Adding dry fuel can lower the measured concentration through dilution, but it does not extract the water already in the tank.

3. Cold-Weather Performance Can Change

Adding FAME to a suitable winter-grade R99 can raise the blend’s cloud point. Depending on the feedstock and concentration, crystals may form at temperatures where the original R99 would remain usable.

The cold-weather performance of the finished mixture must be established rather than assumed from either component.

4. Storage Stability Can Change

FAME can reduce a blend’s resistance to oxidation. As fuel ages, oxidation can contribute to acids, gums, and deposits.

This matters for standby generators and other equipment where fuel remains in storage for extended periods. Mixing a fresh delivery with old fuel does not establish that the resulting mixture is suitable for continued storage.

5. The Final Blend May Exceed Equipment Requirements

FAME can improve lubricity, but it also changes density, viscosity, and evaporation characteristics. These changes become more significant at higher blend levels.

An engine approved for R99 is not automatically approved for every R99/FAME mixture. Confirm the allowable biodiesel percentage and finished-fuel requirements with the equipment manufacturer.

Can Fuel Polishing Fix the Problem?

Fuel polishing can remove solids and, with suitable equipment, free and dispersed water. Ordinary particle filtration, settling, and centrifuging do not directly remove truly dissolved water.

Reducing dissolved water requires an appropriate drying process, such as fuel-compatible vacuum dehydration or a properly selected adsorbent system. Polishing also cannot reverse chemical degradation caused by oxidation.

Water-block filters serve a different purpose. Cim-Tek describes Hydrosorb primarily as a water-alert filter that restricts flow when excess water is detected. It should not be assumed to dry fuel to a specified ppm level.

Know What Is Going Into Your Tank

Before combining deliveries, confirm the fuel type, FAME percentage, water condition, and equipment requirements. Check a separate tank-bottom sample for accumulated water, and use laboratory testing when precise measurements are needed.

Avoid blending unknown fuels to correct contamination. Identify the problem, remove the contamination, and verify the finished fuel. A controlled, documented blend is different from mixing whatever fuel happens to be available.

Dieselcraft helps operators assess contamination and select practical fuel-testing and polishing equipment.

Call 530-613-2150 or visit dieselcraft.com.

The post R99 vs. Biodiesel Blends: Water Retention, Blending Risks & Fuel Care | Dieselcraft appeared first on Dieselcraft.

1. Emulsifiers / Dispersants (“Water Removers”)

These break water into microscopic droplets and suspend them in the fuel. The water then passes through the system and is burned off as vapor.

Pros: Good for small amounts of water, prevents icing, avoids visible free water.

Cons: Doesn’t eliminate water—just sends it to the engine. Too much can cause wear or corrosion. Not ideal for modern high‑pressure systems.

2. Demulsifiers (Preferred for Storage Tanks)

These cause water droplets to combine and settle at the bottom as free water.

Pros: Enables true removal via drains, separators, or polishing. Reduces corrosion and microbial growth.

Cons: Requires a way to physically remove the separated water.

Key Points

•             No additive destroys or converts water; claims otherwise are marketing.

•             Best practice: Use demulsifiers + mechanical removal (drains, separators, polishing).

•             For stored diesel: choose demulsifiers and remove water regularly; avoid strong emulsifiers in bulk tanks without drainage

MORE INFORMATION

The post Why Chemical Fuel Additives Don’t Remove Water from Diesel appeared first on Dieselcraft.

Here are the key questions to investigate:

• Is the fuel clear and bright or cloudy?
• Are you using an additive? If so, which one, at what ratio, and how often?
• Is the entire fuel volume cloudy, or only the bottom around the fuel pick-up?

Fuel Sampling Steps

1. Take a sample from the water separator. Is the fuel clear and bright, or cloudy?
2. Take a sample from the top of the fuel tank. Is it clear and bright, or cloudy?
3. Take a sample from the next fuel delivery. Is it clear and bright, or cloudy?

Checking for Overdosing Issues

• Is your supplier providing a winter blend fuel?
• Is the supplier blending the additive? If so, ask for the exact ratio.
• If the fuel supplier overdosed the fuel—or if you added a cold flow improver to an already treated winter blend—you may have caused the issue.
• Water reacts to excessive additives, preventing it from being trapped by a water-blocking filter.

Understanding Additive Ratios

It’s crucial to use the correct amount of additive:

• There are 128 ounces in 1 gallon.
• If an additive treats 1 gallon per 1,000 gallons of fuel, then 1 ounce treats 7.8 gallons.
• Did you add more than the recommended amount? More is not better!

Locating and Removing the Problem Fuel

• Overdosed additives tend to sink to the tank bottom, where the engine’s fuel pick-up is located.
• Take samples from different points in the tank to determine where clear and bright fuel transitions to cloudy.
• Pump off and store the bottom fuel until the water naturally separates over time.

Testing for Contamination

To test fuel clarity, use this method: Diesel Fuel Contamination Test.
If the results are inconclusive, a lab test ($200–$400) may be required—contact us for recommendations.

Conclusion

Diesel fuel additives are a cost-effective way to improve engine performance in cold weather. They enhance cold flow without sacrificing power or performance and don’t reduce lubricity or cetane levels like kerosene.

However, excessive additive use can cause contamination issues. Based on our findings, the fuel was likely delivered with too much winter blend additive or was overdosed during treatment.

The post Troubleshooting Fuel Contamination Issues appeared first on Dieselcraft.

1. Mechanical Filtration: Most fuel filtration systems employ mechanical filtration, which involves passing the fuel through a filter medium that physically traps particles and contaminants. The filter medium typically consists of a porous material, such as paper, synthetic fibers, or metal mesh, with specific micron ratings to capture particles of various sizes.
2. Micron Ratings: Filters are rated based on their ability to capture particles of a certain size, typically measured in microns. Smaller micron ratings indicate finer filtration, meaning the filter can capture smaller particles. For example, a filter with a 10-micron rating can capture particles as small as 10 microns in size.
3. Contaminant Removal: Fuel filtration systems are designed to remove various types of contaminants, including dirt, debris, rust, water, and microbial growth. Water separation is often a critical function, as water in the fuel can lead to corrosion, microbial growth, and engine damage. Some filters incorporate water-absorbing materials or coalescing elements to separate water from the fuel.
4. Filter Media: The choice of filter media plays a crucial role in the effectiveness of the filtration system. Different materials offer varying degrees of filtration efficiency, flow rates, and compatibility with different types of fuels. Synthetic fibers, such as cellulose or glass fibers, are commonly used due to their high filtration efficiency and durability.
5. Filter Design: The design of the filter element and housing also influences filtration performance. Factors such as the size and shape of the filter element, the surface area available for filtration, and the flow path of the fuel through the filter can affect filtration efficiency and pressure drop.
6. Multiple Filtration Stages: In some applications, multiple filtration stages are used to achieve higher levels of contamination removal. For example, a primary filter may remove larger particles, while a secondary filter with a finer micron rating captures smaller contaminants.
7. Monitoring and Maintenance: Proper monitoring and maintenance of fuel filtration systems are essential for ensuring their effectiveness over time. Regular inspection and replacement of filters, along with monitoring of fuel quality and contamination levels, help prevent system failures and engine damage.
   Overall, effective fuel filtration systems rely on a combination of mechanical filtration, micron ratings, filter media selection, design considerations, and maintenance practices to remove contaminants and ensure clean, reliable fuel delivery to engines. MORE INFO

The post The Science Behind Effective Fuel Filtration Systems: How Do They Work? appeared first on Dieselcraft.

The choice of TFP80 from the other manufactures is too small. Based on its size the residence time of the fuel is less than 20 seconds. Our 5×8 because of the design will give 30 seconds of residence time. Meaning the longer the fuel is in the purifier the longer gravity works on the water to drop it out.

Using the largest possible purifier for longer residence time aka cleaning power and the more capacity to hold water before draining is recommended.

Based on 72 GPH the 5×12 has a residence time of 45 seconds where the 5×16 has a full 60 seconds.
The water sensor will trigger when water reaches the probe at approx 0.400 of 1 gallon. The system will continue to work  unit the volume reached .750 of one gallon then you run the risk of passing water on into the engine. Drain it when the alarm sound or within 3 days not 3 months and the problem will no longer exist.

By using the competitions suggestion the customer will not be happy. His knowledge of how the separation works is lacking. MORE INFO

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