A study shows that 83% of fuel tanks exhibit moderate to severe corrosion, while fuel maintenance is often poorly executed. Overlooking this important component is putting backup power strategies at risk, warns AXI International’s Derek Egan. Louise Frampton reports
Downtime is not an option for mission critical facilities. When the power goes out, multiple systems must function in sequence for a smooth, uninterrupted transition to backup power. If just one of these systems fails, the whole backup power system fails. This is referred to as the ‘failure chain’. Poor attention to fuel quality and maintenance can form part of this failure chain, resulting in unplanned downtime and significant financial losses.
A study conducted by the US Environmental Protection Agency on underground storage tanks (USTs) found that contamination in USTs containing ultra-low sulfur diesel (ULSD) is a widespread problem – 83% of the tanks included in the study exhibited moderate to severe corrosion, yet fewer than a third of tank owners were aware that they had an issue. In fact, corrosion was found to be a problem for both new and old tanks, and for those constructed in both fibreglass and steel.
If not maintained properly, diesel fuel supplying backup generators can carry contaminants such as water, microbes, sludge and particulate matter. Dirt and water are the most significant contaminating factors found in diesel fuel – usually originating from onsite storage tanks, delivery methods to fuel tanks, and fuel tanks themselves. This can have serious consequences:
Injector life reduction
Injector life is reduced by about half with water content above acceptable levels. Water content should optimally stay well below 0.05% of volume. When fuel contains water, it will begin to show a haze and become more opaque. Water content above 0.05% will cause damage to the fuel injection system.
The lubricating properties of diesel fuel are also affected by moisture displacing the fuel. When water passes through an injector, it immediately vaporises, turning into steam. This high-pressure process can damage the injector tips over time.
Water also reduces the combustibility of the fuel being injected.
Water promotes bacterial growth, which results in acidic conditions. These conditions promote corrosion in engine and fuel system components
Asphaltenes can plug filters and damage injectors. They can also affect the combustion efficiency of the engine. Improper fuel droplet size due to damaged injectors, combined with asphaltene particulates, require higher temperatures and compression to fully combust.
With the implementation of High Pressure Common Rail (HPCR), an advancement in fuel system efficiency, the tolerance for fuel contaminants has significantly decreased to 4µ in size.
Any contaminant larger than 4µ can clog or, in the case of water, even blow injector tips. To prevent this, diesel generators have filters to prevent such contaminants from reaching the injectors but, with poor fuel quality, these filters can clog quickly. Once the generator filters are clogged a facility is left with two options – the first is to shut down the generator for maintenance, in order to replace the filters.
However, if the facility is relying on this generator for power, downtime is unavoidable. The second option is to bypass the filters, but in doing so there is nothing to prevent the contaminated fuel from clogging or even blowing the injector tips.
Clogged injector tips will produce inefficient spray patterns, which can result in:
• Low power from the engine
• Reduced engine RPM
• Increased fuel consumption
• Poor cycle times or low speed
• Lower gear selection
• Poor starting
• Poor idle
Blown injector tips require immediate shutdown for replacement and maintenance. Either way, contaminated fuel significantly increases the risk of damage to the generator and downtime for the facility.
Maintenance vs remediation
There are two approaches to keeping diesel fuel emergency-ready – maintenance or remediation – which can have very different outcomes, as AXI International’s Derek Egan explains:
“Remediation is more of a reactive process, where the fuel is cleaned or maintained only because it has failed a lab or onsite test.
“Maintenance, according to our definition, involves creating a proactive plan so that the fuel never falls out of specification, providing no ‘zones of liability’ where the fuel may cause a premature shutdown or failure of the engine in an off-grid event.”
Scheduled fuel polishing can be achieved internally with the purchase of a mobile fuel polishing system (MTC) or outsourced to a fuel polishing company.
However, fuel maintenance systems offer a more proactive approach to ensuring fuel cleanliness.These permanently installed systems run automatically on a programmed schedule to maintain fuel quality indefinitely. Much like dialysis, fuel maintenance systems pull contaminated fuel from the connected tanks for filtration and return clean fuel back to the tanks.
For backup power installations, it is imperative that a systematic approach is applied. Unlike trucks and off-road machinery that consume fuel relatively quickly, diesel gensets store large amounts of fuel for extended periods. Stored diesel fuel can present symptoms of fuel degradation in as little as six months.
In some applications, the genset will see very little use, allowing the fuel to age. This increases the formation of sediments and bacteria in the fuel. In these cases, especially, it is critical that this energy source be maintained.
Egan argues that businesses that require constant uptime should make fuel maintenance a priority: “Fuel systems, especially filtration, are becoming a ‘need to have’ and not just a ‘nice to have’ for stored fuel. We have seen significant improvement in combustion technology over the past 10-15 years, but changes in the fuel supply leave it more vulnerable to long-term storage issues.
“With businesses and global operations continually moving towards the cloud, uptime for mission critical facilities – such as hospitals and data centres – is becoming paramount. The focus has shifted towards redundancy and fuel maintenance. These businesses need to treat fuel like a mission critical component of the backup power system,” he continues.
Automated fuel maintenance systems
Automated fuel maintenance systems eliminate the human element that can lead to failures, contributing to the longevity and performance of critical assets – a benefit that is now well understood by the leading hyperscalers. AXI’s automated fuel maintenance systems have been installed for leading data centre operators – such as Google, Microsoft, Facebook and Amazon, to name just a few. Other sectors need further encouragement to follow their lead, however.
“Hospitals do not have the budget of some large hyperscale data centres and typically keep their fuel management to a service contract.
“While this is a nice way to roll fuel into a maintenance budget instead of a capital expense, it leads to higher liability and potential downtime for the facility,” warns Egan.
He explains that the return on investment for choosing an automated fuel maintenance system over a service contract is typically two to three years depending on the going rate per gallon in the local area.
If undertaken correctly, the liability for having an automated system can be significantly lower than having a third-party service clean the fuel. Preventing downtime and costly repairs is another way to determine an ROI, according to Egan.
“If an emergency standby generator is not able to run as a result of fuel-related problems what is the cost of downtime for the facility? For example, if it is a large data centre, it can cost thousands of pounds for every minute of downtime. If it is a hospital, it can result in loss of life and cost thousands of pounds,” Egan says.
“Having a fuel maintenance system pays for itself by ensuring engine reliability when it is needed the most. It will also extend engine life by preventing damage in vital engine components such as fuel injectors, as well as lower emissions and operating costs.”
In conclusion, the fuel that powers generators is a crucial component of an organisation’s backup power strategy, yet it is often neglected – leading to sludge build-up and contamination. Fuel has a limited shelf-life and even ‘fresh fuel’ can contain water, sediment and microbes upon delivery.
Fuel filters should last thousands of hours, yet frequent filter changes, tank cleaning and replacing fuel have become common maintenance practices that address the symptoms of poor fuel quality and not the problem itself.
Ultimately, when generators run on heavy load, during a power outage, filters can become clogged during the most crucial time. This can ultimately lead to catastrophic failure in the case of a power emergency.
The use of automated fuel filtration systems, along with regular use of a fuel additive, can eliminate liability, eradicate unnecessary risk, and prevent costly downtime.