Will your generator start when the power fails?
An emergency power system has to deliver the moment the mains supply drops out. When a system still fails during a test or in operation, the cause is often the diesel in the tank: water, bacterial growth and sludge that have built up over years without use.
What happens in a tank that stands still
Temperature swings make water condense on the inside walls of the tank. The water settles at the bottom, and bacteria and fungi grow at the interface between water and diesel. This is known as diesel bug. At the same time, particles and degradation products sink to the bottom as sludge.
The industry rule of thumb is that untreated diesel keeps for 6 to 12 months. A standby fuel tank typically has to last much longer.
When the generator starts, the bottom sludge is stirred up and ends up in the fuel filter and the injection system. In other words, the problem only shows itself at the moment the generator is needed.
Why quarterly servicing and additives do not clean the tank
A service inspection tells you the condition of the tank on the day the sample was taken. Between two inspections, water can collect and bacterial growth can develop without anyone noticing.
Biocides kill the bacteria, but the dead bacteria, the water and the sludge stay in the tank. The engine's own filters protect the injection system during operation; they do not clean the tank itself.
An offline filter cleans the tank while the system is on standby
A Delta Xero system is connected to the tank in a kidney loop: the diesel is pumped out of the tank, through a cartridge and back. It cleans the diesel down to 0.1 µmand removes the water, without any change to the installation itself.
Filtration runs continuously, also while the generator is on standby. Particles, free and emulsified water, sludge and bacteria stay in the cartridge, and the cartridge is the system's only wear part. According to industry sources, treated diesel keeps for 18 to 24 months, against 6 to 12 months untreated.
Documented on real installations
A data centre with two diesel tanks of 12,000 litres each had the tanks cleaned from cleanliness code ISO 23/23/22 to 15/13/10 in six days. 99.53% of the water was removed, from 3,831 ppm, and the number of particles above 14 µm fell by 99.95%. The figures were measured by independent analysis.
A British port ran a 22,000-litre diesel tank in round-the-clock operation from below the minimum standard to ISO 16/14/11. And on a site with confirmed diesel bug, the bacteria count fell from over 100,000 to 0, documented in reports before and after treatment.
Clean diesel can also be measured at the exhaust: an independent test on a 478 kW Perkins generator showed 8.5% less NOx and visibly less smoke on the same stored diesel.
Case studies from the industry
22,000-litre port tank in round-the-clock use: from below the standard to ISO 16/14/11
20/19/1916/14/11
ISO 4406 cleanliness code (minimum standard: 18/16/13)
Read the caseData centre: two standby power tanks from critical to approved in six days
23/23/2215/13/10
ISO 4406 cleanliness code (requirement: 18/16/13)
Read the caseWhich model suits your tank?
Enter the tank volume and you get the PT model that suits a standby tank straight away.
What you get
The PT model that suits the tank and the flow it needs to deliver. From there, one click requests a pilot programme with that model: 8 weeks on your own tank, with samples before and after.
The recommendation is a guide and is based on tank volume and refuelling volume. For high water loads, special fuel types or multiple tanks, we are happy to calculate for your installation.
Try it on your own tank
The pilot programme runs for 8 weeks on your own diesel tank, with samples at the start, after 2 weeks and at the end. We analyse the samples ourselves, so results arrive within a few days, and the programme ends with a short report with the before and after figures.
If you are unsure about the condition of the tank, we can start with a diesel sample. Then the numbers decide whether there is a problem.
Contact us, or call76 20 80 10.