How to beat the diesel bugs

Imagine a power failure in a hospital’s intensive care unit. The diesel generator kicks in automatically to resupply power, but then dies. The problem, blocked fuel filters as a result of contaminated fuel. Counties Manukau District Health Board recognises this and has its diesel fuel stocks regularly tested for quality. While the fuel must be within spec it also needs to be maintained in a “fit for purpose” condition, ready for use at any time.

Phil Stichbury, senior engineer for Counties Manukau Health, said the DHB has a number of diesel storage tanks, ranging from 200 to 37,000 litres in capacity, across its properties in Southern Auckland. The tanks supply emergency back-up generators for its main buildings as well as several outlying properties.

Diesel is a rich source of food for microbes known in the industry as ‘diesel bugs’. Once water, even the smallest amount, is introduced the microbes can start the growth process to form biomass (sludge).

Counties Manukau District Health Board’s stock of diesel fuel is checked every 12 months for quality and undergoes mandatory cleaning and treatment if microbial (bug) results are found to be elevated.

The cleaning involves a blend of chemicals and fuel circulation through a fuel cleaning rig, which uses intensive filtration, water separation and ultra violet light.

Kelvin Hieatt, operations manager for Diesel Clean, a company that specialises in monitoring and maintaining fuel quality, says prevention is better than cure.

“Regular monitoring by sampling and testing is the key,” he says. “Microbes, if left too long, can cause extensive damage to both storage tanks and an engines injection system, not to mention disruption to an organisations operation.”

He recalled a recent event where a super yacht was treated for diesel bug. The microbes had eaten more than half way through the aluminium tanks walls.

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