Don't Let Dieseling Destroy Your Hydraulic Systems

One of the most destructive yet preventable issues is dieseling in hydraulic systems. This phenomenon, often triggered by something as simple as using the wrong fluid, can bring your machinery to a grinding halt. The solution starts with a fundamental practice: correctly labeling your fluid tanks.  

Understanding the Dieseling Effect

Dieseling, also known as the "diesel effect," is a damaging event that occurs within a hydraulic system. It happens when air or other gas bubbles mix with hydraulic fluid and are rapidly compressed. This compression generates intense heat, causing the air-and-fluid mixture to ignite—much like fuel in a diesel engine. The hydraulic cylinder essentially becomes a combustion chamber, leading to micro-explosions that can wreak havoc on your equipment.

The Causes of Dieseling

Dieseling isn't a random event; it's the result of specific system vulnerabilities. The primary trigger is air entering the hydraulic system. Common causes include:

• Air Leaks: Worn or faulty seals, loose fittings, and damaged hoses are common culprits that allow air to be drawn into the system.

• Not Allowing Returned Oil Time to De-gas: To address this, ensure the reservoir is sized at a 3:1 ratio of tank capacity to pump GPM. Additionally, always return the oil below the fluid level to prevent splashing and promote optimal system performance.

• Rapid Compression: Abrupt or high-speed cylinder movements can compress trapped air too quickly, generating the heat needed for ignition.

• Low Fluid Levels: When the hydraulic fluid level is too low, the pump can draw in air from the reservoir.

• Improper Purging: Failing to properly bleed the system of air after maintenance or commissioning leaves it vulnerable.

• Incompatible Fluids: Mixing different types of hydraulic fluids, or using one not specified for the system, can increase the likelihood of dieseling.

The Damaging Effects of Dieseling

The consequences of dieseling extend far beyond a momentary bang or knock. These micro-explosions create a chain reaction of damage that compromises the entire system.

• Seal and Component Damage: The intense heat generated by dieseling can cause seals to burn, harden, and crack. This leads to leaks, which allows more contaminants to enter the system. The explosive pressure can also erode or damage metallic components like valves and pumps.

• Reduced System Efficiency: A system affected by dieseling often becomes sluggish and unresponsive. The internal damage and fluid degradation prevent actuators from moving smoothly, hindering performance.

• Increased Maintenance and Downtime: Frequent dieseling events necessitate costly repairs and component replacements. The unplanned downtime can disrupt operations and lead to significant financial losses.

• Fluid Degradation: The combustion process ages the hydraulic oil rapidly, diminishing its lubricating properties. You might notice the fluid turning dark or black, contaminated with soot-like particles from the explosions.

Why Proper Tank Labeling Is Non-Negotiable

It's easy to see how fluid contamination is a major risk factor for dieseling. One of the most common—and entirely avoidable—causes of contamination is fluid misidentification. When an operator tops off a hydraulic tank with the wrong fluid because of a missing or incorrect label, the system's integrity is immediately compromised.

Mixing incompatible fluids can lower the fluid’s flash point or introduce properties that promote aeration, creating the perfect conditions for dieseling. The financial and operational impacts are severe. A single mistake can lead to thousands of dollars in repairs, weeks of downtime, and a cascade of operational delays. Clear, consistent labeling is a small investment that protects against these monumental losses.

Best Practices for Labeling Hydraulic Tanks

Implementing a robust labeling system is a straightforward process that pays dividends in equipment reliability and safety.

• Use Clear and Durable Labels: Labels should clearly state the fluid type, grade, and any relevant specifications (e.g., ISO VG 46 Hydraulic Oil). They must be durable enough to withstand harsh environmental conditions without fading or peeling.

• Implement Color-Coding: Assign specific colors to different fluid types. For example, use blue for hydraulic fluid, red for transmission fluid, and yellow for diesel fuel. This provides an immediate visual cue that helps prevent cross-contamination.

• Label All Fill Points: Place labels not only on the main tank but also on all fill ports and any transfer containers used for topping off fluids.

• Train Your Personnel: A labeling system is only effective if your team understands and follows it. Train all operators and maintenance staff to recognize the labels, understand the color-coding system, and adhere strictly to the procedures.

Proactive Strategies to Prevent Dieseling

While labeling is a critical first step, a comprehensive prevention strategy involves regular maintenance and operational diligence.

• Regular System Inspections: Routinely check for leaks in hoses, fittings, and seals. Tighten loose connections and replace worn components at the first sign of wear.

• Proper Bleeding Procedures: Always bleed the hydraulic system to purge trapped air after maintenance or when commissioning new equipment. This involves stroking the cylinders through their full range of motion without load to force out any air bubbles.

• Use High-Quality, Compatible Fluids: Select the correct hydraulic fluid as specified by the equipment manufacturer. Using high-quality fluids with anti-foaming agents can significantly reduce the risk of aeration.

• Monitor Fluid Levels and Conditions: Regularly check the fluid level in the reservoir to ensure it is adequate. Monitor the fluid for signs of degradation, such as a dark color or burnt smell, which can indicate dieseling has occurred.

• Avoid Abrupt Movements: Operate equipment smoothly, avoiding sudden, jerky movements that cause rapid compression.

Preventing dieseling requires a proactive approach that combines proper fluid management with diligent system maintenance. Clear labeling of mobile equipment tanks is the simplest yet most effective measure you can take to prevent catastrophic fluid contamination and the destructive dieseling that follows. By establishing and enforcing these best practices, you protect your valuable equipment, ensure operational efficiency, and safeguard your bottom line.

At Bailey International, we are more than just a hydraulic components supplier—we’re your trusted partner in growth. For half a century, we have specialized in providing high-quality hydraulic components, including cylinders, valves, and custom solutions, to help businesses like yours operate safely and efficiently. Our experts are ready to help you select the right components and design a system built for optimal performance.