Kathon FP1.5 for Jet Fuel


Kathon FP 1.5 microbicide from Rohm and Haas is a patented, high performance antimicrobial agent, developed specifically to combat problems of microbial contamination and spoilage in hydrocarbon fuels. The effectiveness of Kathon FP 1.5 has been proven over a number of years and it has extensive approvals endorsing its use in a range of fuel types - including civil and military aviation fuels.

Development of Microbial Growth

Microbial contamination is likely to occur wherever fuel and water come into contact, either in fuel tanks or distribution systems. Modern fuelling technology ensures that fuel, on entering the aircraft, is almost totally free of undissolved water. However, temperature variations on the ground and in flight result in the condensation of atmospheric humidity or dissolved water within the fuel tank. This condensation builds up to form a water bottom.

Micro-organisms can be air and waterborne. Therefore as the water bottom develops a microbial population becomes established in it. For many of the species present in the water bottom, the fuel represents an ideal nutrient source. These organisms flourish, living in the water phase, whilst feeding on the fuel or tank coatings.

In the early cases of contamination the fungus Cladosporium resinae (now known as Hormoconis resinae) was the predominant organism. Subsequently, many other organisms (bacteria, fungi and yeasts) have been identified as contaminants including pathogens in aviation fuels. This is a consequence of both the adaptation of microbial species and greater international travel, which has aided the global proliferation of fuel contaminants.


Fuel tanks and sumps should be drained of water regularly. Whenever periodic maintenance is carried out, tanks should be checked for slime growth. The maintenance programme mentioned above will reduce the likelihood of microbial contamination. The use of Kathon FP 1.5 in combination with such a maintenance programme will decrease the risk of contamination to a minimum.

Consequences of Contamination

Microbial contamination endangers both fuel quality and fuel systems. Some of the common manifestations and consequences of the problem are outlined below.

Fuel Quality:
Aviation fuel should be "clear and bright". Contaminated fuel is often hazy. The primary cause is an increase in the water content of the fuel resulting from the production of biosurfactants. These are by-products of microbial growth and alter the surface tension at the fuel/water interface. In consequence. the solubility of water in the fuel is increased.

Additive Degradation:
Many additives present in fuels can be readily degraded by micro-organisms. This means their effect is lost and in consequence the fuel may no longer meet specification.

Structural Damage:
Certain micro-organisms can digest components of surface coatings or fuel lines, thus greatly reducing their in service life. Others, known as sulphate reducing bacteria (SRB), cause microbially induced pitting corrosion.

Filter Plugging:
Biopolymers are formed during microbial growth. These are gummy products which block fuel lines and plug filters.

Slime Growth:
Some micro-organisms grow to form filamentous slimes. These slimes can either float in the fuel, where they plug filters or adhere to surfaces. If slime adheres to equipment, for example a fuel gauge may give erratic readings. In addition the susceptibility to microbial induced corrosion of surfaces covered with slime is greatly increased.

KATHON FP 1.5 Performance Benefits

Kathon FP 1.5 has been designed to eradicate all kinds of microbial contamination. It therefore offers a number of outstanding performance benefits.

Approvals:  Kathon FP 1.5 is widely approved for use in Military and Civil aviation fuels. Details of the approvals status of Kathon FP 1.5 are given here.
Speed of kill : Kathon FP 1.5 causes immediate inhibition of growth on coming into contact with a micro-organism. Growth inhibition rapidly becomes irreversible and results in cell death. This ensures rapid eradication of contamination (8-12 hours).
Broad Spectrum Activity: Kathon FP 1.5 is effective against all commonly occurring aviation fuel contaminants (bacteria, fungi and yeasts).
Long Term Preservation: Fuel treated with Kathon FP 1.5 will remain protected from contamination over long periods of time. It will also resist contamination if reinnoculated from another source.
Complete System Protection: The partitioning characteristics of Kathon FP 1.5 ensure that it is present in both the fuel and the water phases. This enables: 
a) Eradication of contamination in the water bottom, without hydrolysis 
b) Protection of the treated fuel if transferred through a distribution system
Ease of use: Kathon FP 1.5 is easily dosed into fuel. No special storage conditions for Kathon FP 1.5 are required.
Safety and support: Rohm and Haas offers customers a comprehensive package of support services and data to promote the safe and effective use of Kathon FP 1.5. This includes extensive data on environmental fate, toxicology, materials compatibility and assistance in areas such as disposal and product handling.
No time constraint on use of fuel after treatment:  Jet fuel containing Kathon FP 1.5 can be stored for several months before use.
Dosing of KATHON FP 1.5 

Kathon FP 1.5 should be added preferably by means of metered injection into the fuel line during aircraft refuelling. This ensures accurate dosing and even distribution of the production in the fuel. Suitable metering systems are available from several suppliers. Please contact your local Rohm and Haas office for recommendations.

Overwing dosing is not recommended for reasons of worker safety and dosing accuracy. If these difficulties and good mixing of the product can be ensured, then overwing dosing will give equivalent results to metered injection.

Kathon FP 1.5 at recommended use levels will eradicate commonly occurring fuel contaminants in 8-12 hours. Following treatment, dead micro-organisms and other debris from the treated fuel will accumulate on the tank bottoms. This should be drained off. Filters should also be checked frequently and examined for the build up of suspended solids.

Kathon FP 1.5 should be used as a part of routine fuel system maintenance programme. Biocide treatment is a complement to and not a substitute for good housekeeping.

Dose Levels: Kathon FP 1.5 recommended use level in aircraft fuel tank is 100 ppm.
Never dose Kathon FP 1.5 as supplied into an empty fuel tank.

dose levels chart kathon.jpg

Handling Safety

Use of a metered injection system to dose Kathon FP 1.5 minimises worker exposure to the product as supplied. On those occasions where Kathon FP 1.5 is handled directly appropriate precautions should be taken.

Avoid dermal and eye contact. Suitable protective clothing should be worn, including nitrile rubber gloves and safety goggles/face shield.

After working with Kathon FP 1.5, wash thoroughly with soap and water, particularly before eating, drinking or smoking.


Low levels of the active ingredients of Kathon FP 1.5 will be present in water drained from aircraft using treated fuel. This water can be discharged to a municipal or chemical sewer. Do not discharge directly to open bodies of water. Water pH is not modified by the presence of Kathon FP 1.5.

N.B. : This guideline applies only to water discharged from aircraft fuel tanks. Information relating to disposal of water bottoms from bulk storage tanks is given in the Kathon FP 1.5 Safety Guidelines.
Detailed information on handling, storage, environmental effects and other safety issues is given in the Safety Guidelines Bulletin for Kathon FP 1.5.

Chemical and Physical Properties

The active ingredients of Kathon FP 1.5 are identified using the IUPAC nomenclature as 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one.

Structural Formulae Kathon.jpg

Properties of Kathon FP 1.5
 Yellow Liquid  
 pH (as producted)
 4 - 6
 Specific Gravity (25°C)
 Viscosity (25°C)
 97.8 CpS

These values do not constitute specifications

A solution of 5-chloro-2-methyl-4-isothiazolin-3-one, and  2-methyl-4-isothiazolin-3-one
A broad spectrum fuel biocide.
Clear colourless to pale yellow liquid
1.04 at 25.00OC
pH (10 % solution)
Hazardous Components
Active components are irritants
Volatile Components   
Not flammable
Soluble in water in all proportions
Potential Hazards   
May be harmful if ingested
Shelf Life    
Retention of > 95% actives in 12 months
Store in a warm, dry area protected from frost or excessive heat

Irritating to skin
Risk of serious damage to eyes
May cause sensitization by skin contact
Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment
Wear goggles, PVC or rubber gloves, and protective clothing
Absorb in inert material and dispose of in accordance with local regulations
Inhalation: Move to fresh air. Give artificial respiration if breathing has stopped. If symptoms persist, call a physician.
Skin contact: IMMEDIATELY get under a safety shower. Remove contaminated clothing. Wash off with soap and water. Immediate medical attention is required. Wash contaminated clothing before re-use. Do not take clothing home to be laundered. Discard contaminated shoes, belts, and other articles made of leather.
Eye contact: Rinse immediately with plenty of water for at least 15 minutes. Immediate medical attention is required.
Ingestion: Drink 1 or 2 glasses of water. IMMEDIATELY see a physician. Never give anything by mouth to an unconscious person
Classification for ROAD and Rail transport (ADR/RID):  Not regulated (Not dangerous for transport)
Classification for SEA transport (IMO-IMDG):   Not regulated (Not dangerous for transport)
Classification for AIR transport (IATA/ICAO):   Not regulated (Not dangerous for transport)
Links to further information
Performance Charts

For other Kathon data, including MSDS, the current brochure and the approval and compatibiltiy list, please refer to our Documentation section.


Kathon is a trade name of Rohm & Haas Co. Philadelphia

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