RECAP | ROUNDTABLE | Maintaining fuel quality

Introduction: Poor fuel quality remains a vulnerability in many data center operations, threatening the reliable operations of even well-maintained generators. Solutions range from proper fuel sampling and testing to filtration techniques to introducing appropriate additives to extend the life of the fuel. Terry Altom, Uptime Institute senior consultant, joined a roundtable panel discussion of how enterprises can eliminate downtime risk due to poor fuel quality.

Terry started the session by explaining how oil companies supply a certain amount of water within their fuels. Venting systems pull air/oxygen into tanks causing potential for additional water. Water and oxygen also create the ability for bacteria to form and de-grade the fuel. Therefore, the need for maintaining and checking fuel quality is vital to data center engine-generator operations.

Best Practices: The attendees discussed what they primarily are doing to maintain top fuel quality.
• Fuel testing, usually done at least on an annual basis per tank. Indications are some companies will test more frequently than annually, ranging from an extreme of quarterly to semi-annually. One attendee indicated their colo customers are asking for quarterly lab tests of fuel, probably because of a bad experience they once had. Most other attendees indicated they do not normally test as frequently. Additives would be applied as needed based on test results. Test results should be trended as well.
• Fuel sampling, referred to as the white bucket test. This is a visual inspection where you are looking for the fuel to be clear and bright. This test is predominantly done with every fuel delivery.
• Fuel delivery testing is normally conducted as well. This ranges from testing every truck load to testing the supplier annually. Some facilities have designed a fuel holding tank into their system to keep fuel isolated until test results are known.
• Polishing systems. Typically, these systems are utilized on larger scale tank installations. Polishing the fuel within a larger tank is usually done weekly or rotated each week between tanks so that each tank is at least polished monthly.
• Find yourself at least one good and reliable fuel supplier. It was discussed how partnering with a fuel supplier is a really good idea because it provides you with standardized service. This would allow you to conduct annual fuel supplier testing, and get consistent and dependable service.
• If you do not churn a lot of fuel, a good practice is refreshing fuel – pumping existing fuel out, filtering, and recirculating back into tanks. Testing and trending the results can help determine how often this would need to be done.
• Try and keep your tanks as full as possible because it means less space for moisture to develop.
• It is a great practice to understand the fuel quality of your region in order to establish your fuel quality maintenance plan. One attendee indicated they are moving to testing quarterly because of regional supplier concerns. They also found the fuel filtration system was causing issues, which lead them to adjust their testing and maintenance plan.
• It is a great practice to establish a fuel quality standard that would include all the above. One attendee indicated they are moving toward creating a global standard.

Issues with fuel polishing systems was discussed. Not sizing the polishing system properly has been an issue. This would mean under-sizing the system. Another concern is whether polishing is actually getting all the fuel. Polishing system suction should be on one end of the tank with discharge on the other end and be as close to the bottom as possible.

An attendee asked if anyone has experienced any issues with diesel exhaust fluid (DEF). DEF is a liquid used to reduce the air pollution caused by diesel engine exhaust. The fluid is typically a urea solution that is injected into the exhaust stream as part of a selective catalytic reduction (SCR) system. The system can cause the engine to shut down and not be allowed to run if not operating properly. Common causes of DEF shutdown are due to clogged injector spray nozzles. Typically, the life expectancy of the DEF is not an issue.

Another attendee indicated they are being asked to consider using renewable diesel fuel (biomass derived). They are pushing back because of the newness and uncertainty of using the fuel. For example, does it derate the capacity of the engine, and is there any history on the ability to store the fuel? The primary reasons for using renewable diesel fuel is because it reduces greenhouse gas emissions verses using conventional diesel fuel. Other attendees indicated they have no experience with renewable diesel.