Diesel microbial contamination
A preventive approach to fuel system reliability
Fuel problems, clogged filters, injector failures, engine or equipment breakdowns too often?
Diesel microbial contamination is one of the most common yet often underestimated causes of fuel system problems..
The issue is not limited to clogged filters – over time it can compromise the reliability and service life of the entire fuel system.
The risk is particularly high in:
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backup power systems
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marine and ferry operations
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public transport
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industrial and critical facilities
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long-term diesel storage
Merina provides controlled and documented solutions for preventing and managing microbial contamination in diesel fuel, with Grotamar used as part of a structured fuel quality management approach.
What does diesel microbial contamination mean in practice?
Diesel microbial contamination refers to bacteria, yeasts and fungi that grow in diesel fuel, especially at the fuel–water interface.
Microbial growth may lead to:
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sludge and biofilm formation
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clogged filters and flow restrictions
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degraded fuel quality and water retention
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formation of organic acids
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localized corrosion in tanks and piping
Problems often develop slowly and remain unnoticed until operational issues or damage occur.
Why can microbial contamination damage injectors and fuel systems?
The impact of microbial contamination is not purely mechanical.
Microorganisms produce organic acids as metabolic by-products, which over time can:
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cause acidic corrosion
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weaken metal surfaces and coatings
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stress high-pressure pumps and injectors
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shorten component service life
Modern diesel systems are particularly sensitive due to tight tolerances and high demands on fuel cleanliness and chemical stability.
A clogged filter is often the first visible symptom – but the underlying process is frequently chemical and progressive.
Why filter replacement alone is not enough?
Replacing filters treats the symptom, not necessarily the root cause.
If:
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microbial growth continues
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water remains in the system
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acid formation persists
→ the risks quickly return.
Effective fuel management therefore requires a combination of mechanical, chemical and monitoring measures.
Grotamar as part of a controlled solution
Grotamar is a proven and effective biocide for controlling microbial growth in diesel fuel.
At Merina, Grotamar is:
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not used routinely
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not applied blindly
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not treated as a stand-alone product
Its use is based on:
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verified need
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controlled and documented dosing
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analysis or technical assessment
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long-term, preventive fuel care
Preventive fuel care for critical applications
In many systems, problems are detected only after damage has already occurred.
To address this, we offer a preventive fuel care model where:
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fuel condition is monitored regularly
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additives are used only when technically justified
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actions are documented
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risks are identified before failures occur
Who is this solution for?
Our solutions are designed for organizations where fuel quality is a reliability and risk management issue, not merely a cost factor:
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backup power and critical infrastructure
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marine and ferry operations
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industrial facilities
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public sector and authorities
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long-term diesel fuel storage
Contact us
If you suspect microbial contamination or recurring fuel system issues, contact us for a professional assessment of your fuel condition.
Our experience in fuel cleanliness
We have been analysing fuels and oils, with a particular focus on microbial contamination, since 2006. We have extensive expertise in diesel fuel quality and the cleanliness of fuel storage tanks.
Our cooperation with leading international industry players gives our customers access to the latest knowledge, best practices and technical expertise.