35 DIPSLIDES

Bacterial testing of systems should take place on a weekly basis and when bunkering incubating dipslides for 24 hrs at 25-3OºC

Product A - Combination Dipslide for aerobic/coliform (SCT)

Product B Combination Dipslide for aerobic yeast & fungi (RBS)

Product C - Culture tube for anaerobic bacteria (SRB)

Bacterial Contamination Oil Systems:

Microbe Monitoring. In oil technology, microbes can be defined as comprising bacteria, yeasts and fungus. All these, when present, can attack additives in the oil and change them chemically so that they no longer function in the way intended and simultaneously there is a reduction in the quantity present.

In addition to the chemicals present in the oil emulsion, extra food can be provided by the addition of leakages of any fluids draining into the system. This additional food causes the microbes to multiply more quickly. Quick identification of the presence of bacteria will mean that the problem can be treated before mechanical breakdown occurs. When testing with dipslides in oil dip the slide where possible into the water phase of the oil or preferably the oil/water interphase.

Aerobic:

These exist mostly as small rods. They would almost certainly always be present in the bilges.

They are detected by the Aerobic Yeast & Fungi Dipslide. The colonies are easily seen.

Yeast and Fungi:

These are less common than bacteria, but are one hundred times larger than bacteria and, therefore, only 10,000 yeasts will attack the chemicals as much as 1,000,000 bacteria.

They are more resistant to biocide attack than bacteria and it is necessary that the biocide used in the oil will kill these as well as bacteria.

Ease of use and a wide range of applications make the Aquamarine Dip Slide range the ideal answer for service engineers and busy laboratories where speed and repeatability are primary requirements.

Anaerobic Bacteria (Culture Tube Test):

These exist when the oil is stagnant. They reduce chemicals in the oil emulsion to give hydrogen sulphide which is the noxious ‘Rotten Egg’ smell given off when the oil is disturbed. They also give off acids which reduce the alkalinity of the emulsion and in certain cases promote corrosion.

Coliform Bacteria:

These are bile tolerant bacteria which pass through the body of animals or man and emerge in the faeces. Whilst they are not necessarily pathogenic there are pathogenic bacteria usually associated with them. These are usually shigella and salmonella. It is easier to detect the Coliform bacteria which are present in greater numbers.

If a significant number - say 10/5 colonies/ml - are regularly found, medical advice should be sought.

The majority of bacteria found in oils are non-pathogenic, but there are occasions when "opportunist’ pathogenic bacteria may be present. There are at least three ways in which these can enter the body: -

(a) Ingestion of spray. Spray removal equipment should be used.

(b) Entry through cuts in the skin. These should be protected.

(c) Entry through defatted skin pores.

Paraffin or similar solvents should not be used to wash hands. Barrier creams and proper non-abrasive soaps should be provided.

The possibilities for unrestricted growth of bacteria should be minimised and this can be summed up

(a) Good housekeeping to keep oils clean i.e. pipes, storage and stop water leakages into oil systems

(b) Clean the tanks, pipes, with a steriliser/cleaner before introduction of fresh oil

(c) Use an oil containing a biocide effective against bacteria, yeasts and fungus (Aquamarine Aquabac)

(d) Identify by testing first stages of bacterial contamination so that the problem may be treated.

Bacterial Contamination in Water Systems:

The Coliform slide may be used to check all water systems including cooling water, ballast and boilers. The count is not high enough to give a low enough count for drinking water systems but will identify a potential risk of system fouling or risk of Legionella disease i.e. see dipslide user guide. A full RBS/SCT/SRB check is recommended.

Aquamarine can offer full advice on treatment of all forms of Bacterial contamination.