Mechanism and Long-Term Efficacy of PMX 145 Fuel Biocide in Diesel and Biodiesel Storage Systems

Abstract

Microbial contamination is a well-documented cause of fuel degradation, corrosion, and operational failure in diesel and biodiesel storage systems. The presence of water within fuel tanks enables microbial growth at the fuel–water interface, leading to sludge formation, filter blockage, and material damage. This paper describes the mechanism of action, post-treatment behavior, and long-term protective characteristics of PMX 145, a fuel biocide formulated for use in diesel and biodiesel applications. Emphasis is placed on its suspension behavior, microbial control pathway, fuel specification compatibility, and suitability for long-term storage environments.

Introduction

Diesel and biodiesel fuels are susceptible to microbial contamination when water is present in storage systems. Even limited water ingress from condensation, precipitation, or compromised seals can create favorable conditions for microbial proliferation. Once established, microbial colonies generate biomass and acidic by-products that degrade fuel quality and damage storage and fuel delivery infrastructure.

Biodiesel and biodiesel blends exhibit increased hygroscopicity relative to conventional diesel, resulting in greater moisture absorption and elevated contamination risk. Consequently, microbial control is a critical component of fuel storage management, particularly for long-term or remote storage applications.

Microbial Growth in Fuel Systems

Microorganisms are unable to survive in hydrocarbon fuel alone and instead colonize the interface between fuel and free water. At this boundary, bacteria and fungi utilize available nutrients and multiply rapidly. The resulting contamination manifests as:

• Biomass accumulation (sludge and biofilm)
• Organic acid production
• Fuel degradation
• Corrosion of tanks and components
• Filter plugging and system restriction

If left untreated, microbial contamination propagates throughout the fuel system, increasing maintenance costs and operational risk.

PMX 145 Formulation Characteristics

PMX 145 is a fuel biocide engineered to remain suspended throughout the fuel phase rather than separating or settling. This suspension behavior enables uniform distribution within the tank and continuous contact with microorganisms across fuel layers, tank surfaces, water zones, and downstream components such as filters.

Uniform additive dispersion is a key factor in effective microbial control, particularly in large or irregular storage systems where stratification can limit treatment effectiveness.

Mechanism of Action

Microbial Inactivation

Upon introduction into contaminated fuel, PMX 145 interacts with active microbial populations, resulting in microbial inactivation and cessation of growth. This interrupts the contamination cycle and prevents further colony expansion.

Contaminant Settling

Following microbial death, biomass aggregates and increases in density. Heavier contamination subsequently settles to the bottom of the tank, facilitating removal through controlled draining or tank cleaning procedures.

Residual Fuel Protection

PMX 145 remains present in the treated fuel after initial remediation. This residual presence allows the additive to continue functioning within the system rather than acting as a single-use treatment.

Biostatic Function

At maintained concentrations, PMX 145 provides ongoing biostatic activity, inhibiting re-establishment of microbial colonies within the tank and associated fuel system components.

Observed Post-Treatment Outcomes

• Elimination of active microbial growth
• Separation and settling of contamination for removal
• Continued microbial suppression due to residual biocide presence
• Reduced likelihood of recurrent contamination

These characteristics support both corrective and preventative use cases.

Handling and Safety Considerations

PMX 145 is classified as non-hazardous for handling and storage. This distinguishes it from many conventional fuel biocides that carry hazardous material classifications and associated transport, storage, and occupational safety requirements.

• Simplified storage and logistics
• Reduced handling risk for personnel
• Suitability for on-site use in diverse environments

Fuel Specification Compatibility

PMX 145 is formulated to preserve fuel quality and compliance. Treated diesel fuel remains within ASTM D975 specification limits, ensuring that performance and safety characteristics of the fuel are not adversely affected by biocide application.

Long-Term Performance

• Greater than five years of protection in conventional diesel
• Greater than two years of protection in biodiesel and biodiesel blends

This duration supports use in long-term storage, standby power systems, and infrequently cycled fuel inventories.

Complementary Fuel Stability Strategies

For extended storage applications, PMX 145 may be used in conjunction with combustion and fuel stability additives, such as FTC Decarbonizer, to address non-biological degradation mechanisms. In such configurations, PMX 145 provides microbial control while complementary additives support combustion efficiency and deposit management.

Conclusion

PMX 145 provides an integrated approach to microbial control in diesel and biodiesel storage systems by combining rapid microbial inactivation, contamination separation, and long-term biostatic protection. Its suspension behavior, non-hazardous handling profile, and ASTM D975 compatibility make it suitable for both remediation and preventative maintenance strategies. When applied as part of a comprehensive fuel management program, PMX 145 supports sustained fuel quality and reduced operational risk over extended storage periods.