Fuel monitoring for data center diesel generators - how to do it and why is it so important?

The quality of the power supply system is the most important indicator of the level of service of a modern data center. This is understandable: absolutely all the equipment necessary for the operation of the data center is powered by electricity. It will not be there - servers, network, engineering systems and storage systems will stop functioning until the power supply is completely restored.



We tell you what role diesel fuel and our quality control system play in the uninterrupted operation of the Linxdatacenter data center in St. Petersburg.



You will be surprised, but the specialists of Uptime Institute, when certifying data centers for compliance with industry quality standards, play the primary role in evaluating the power supply system for the quality of diesel generators.



Why? The smooth operation of the data center plays a central role in the digital economy. The realities are: 15 milliseconds of a power outage in the data center is enough to disrupt business processes with tangible consequences for the end user. Is it a lot or a little? One millisecond (ms) is a unit of time equal to one thousandth of a second. Five milliseconds is the time it takes for a bee to take one wing stroke. To blink, a person needs 300-400 ms. One minute of downtime back in 2013 cost companies an average of $ 7,900, according to Emerson. Amid increasing digitalization of the business, losses can amount to hundreds of thousands of dollars for every 60 seconds of downtime. The economy requires 100% business connectivity.



And yet, why are diesel generators considered by UI the main source of power supply? Because in the event of a disconnection of the main power supply networks, the data center can rely on them as the only power source to maintain the operability of all systems until the current supply through the main channels is restored.



For our data center in St. Petersburg, issues related to power sources play a particularly important role: the data center is completely independent of the city network and is provided with electricity through a 12 mW gas-piston power plant. If the gas supply is interrupted for some reason, the data center switches to work at the diesel generator set. First, UPSs are launched, the capacities of which are enough for 40 minutes of uninterrupted operation of the data center, diesel generators are started within 2 minutes after the gas-piston station stops working and operate on the available fuel supply for at least another 72 hours. In parallel, a contract with the fuel supplier will enter into force, which is obliged to bring the agreed volumes to the data center within 4 hours.



Preparation for certification of the Uptime Institute for compliance with the standards of operational management Management & Operations forced us to pay close attention to the process of supplying diesel fuel, quality control, interaction with suppliers, etc. This is logical: the quality of the nuclear power plant in Sosnovy Bor does not depend on us, but we must be fully responsible for our section of the electric network.

DT for data centers: what to look for

In order for the generators to work for a long time, reliably and economically, one should not only acquire reliable equipment, but also choose the right diesel fuel (DT) for them.



From the obvious: any fuel has a shelf life of 3-5 years. It also varies quite a lot in various parameters: one type of it is suitable for use in winter, the other is completely unsuitable for this, and its use will lead to a large-scale accident.



All these points must be carefully monitored in order to prevent the situation when the diesel engine is not started due to expired or improper fuel seasonally.



One of the most important classification parameters is the type of fuel used. The high performance and reliability of the equipment is already affected by the quality of the selected type from a particular supplier.



The right choice of diesel fuel will provide the following advantages:

• high efficiency;
  
  
• profitability and low cost;
  
  
• high torque;
  
  
• high compression ratio.
  
  

Cetane number

In fact, DT has many characteristics that you can study in the passport of a particular batch of products. However, for specialists, the main criteria for determining the quality of this type of fuel are the cetane number and temperature properties.



The cetane number in the composition of the diesel fuel determines the starting ability, i.e. ignition ability of a fuel. The higher this number, the faster the fuel burns in the chamber - and the more evenly (and safer!) The mixture of diesel and air burns. The standard range of its indicators is 40-55. High-quality diesel fuel with a high value of cetane number provides the engine: the minimum time required for heating and ignition, uniform operation and economy, as well as high power.

Diesel cleaning

The ingress of water and mechanical impurities into diesel fuel is even more dangerous than for gasoline. Such fuel may become unusable. In some cases, the presence of mechanical impurities can be detected as sediment at the bottom of the tank with diesel fuel.

Water also exfoliates from the fuel and settles at the bottom, which makes it possible to establish its presence. In an undetermined diesel fuel, water causes turbidity.



Improving the performance will help the cleaning of diesel fuel. There are special installations and filtering systems for this. The choice of equipment for such a procedure depends on what it is necessary to clean the fuel from - paraffin, solids, sulfur or water.



The supplier is responsible for the quality of fuel cleaning, which is why it is important to have a supplier control system, which we will talk about below and not to forget about additional measures. So, for fuel post-treatment we installed Separ fuel separators on the fuel line of each diesel generator set. They prevent mechanical particles and water from entering the generator.





Fuel separator.

Weather

In the pursuit of quality and affordable fuel prices, companies often forget about the temperature at which the station will operate. Sometimes the choice of one fuel "for any weather" does not bring much harm. But if the station is used outdoors, it is worth choosing fuel in accordance with climatic realities.



Manufacturers divide diesel into summer, winter and “Arctic” - for extremely low temperatures. In Russia, GOST 305-82 is responsible for the separation of fuel according to the seasons. The document prescribes the use of summer grades of fuel at temperatures above 0 ° C. Winter fuel is suitable for applications up to -30 ° C. “Arctic” - in cold weather up to -50 ° C.



For the stable operation of diesel generators, we decided to purchase winter diesel fuel -35 ℃. This allows you not to think about seasonal weather changes.

How do we check fuel

For diesel generators to work reliably, you need to make sure that the supplier ships exactly the fuel that you need.



We thought for a long time about solving this problem, considered the option of sampling and sending them for analysis to special laboratories. However, such an approach takes time, and what to do if the analyzes are unsatisfactory? The party has already been shipped - return, reorder? And what if such a reorder occurs during the period when it is necessary to start the generators?



And then we decided to measure the quality of fuel on the spot, with the help of octanometers, specifically - using the SHATOX SX-150. This device allows for rapid analysis of the supplied fuel, determining not only the cetane number, but also the pour point and type of fuel.



The principle of operation of the octanometer is based on a comparison of the octane / cetane numbers of certified DT / gasoline samples with the tested DT / gasoline. Used tables of certified fuels are introduced into the special processor, which the interpolation program compares with the parameters of the sample taken and with adjustments for the temperature of the sample.







This device allows you to get fuel quality results in real time. The rules for measuring fuel quality using an octanometer are recorded in the regulations for the operating service.

The principle of operation of the octanometer

1. The sensor of the device is mounted on a horizontal surface and connected to the measuring unit.
2. The device turns on when the sensor is empty. CETANE zero readings are displayed on the measuring device:
   
   
   • Cet = 0.0;
   • T fr = 0.0.
3. After checking the operation of the device, it is necessary to pour fuel into the sensor until it is full. The process of measuring and updating readings takes no more than 5 s.
4. After the measurement, the data are entered into the table and compared with the norm readings. For convenience, the cells are set to automatically highlight the values ​​with color. With acceptable readings, it turns green, with unsatisfactory parameters - red, which allows you to further control the parameters of the supplied fuel.
5. For ourselves, we chose the following normal fuel quality readings:
   
   
   • Cet = 40-52;
   • Tfr = from minus 25 to minus 40.

Fuel Accounting Table

S - summer fuel, W - winter, A - arctic.

PROFIT! or how did it work

Actually, we began to receive the first results of the project immediately after the launch of the control system in operation. The first control showed that the supplier brought fuel that did not meet the declared parameters. As a result, we sent the tank back and requested a replacement party. Without a control system, we could run into a situation of non-launch of diesel generator sets due to poor fuel quality.



In the most general, strategic plan, such a level of thoughtfulness of quality control gives complete confidence in the uninterrupted supply of the data center, when we can fully rely on ourselves in solving the problem of supporting a 100% uptime operating mode of the site.



And these are not just words: perhaps we are the only data center in Russia, which, when conducting a demonstration tour for the client, asking, “Can you disconnect from the main power supply to show the transition to the backup?”, We agree and right there, in front of our eyes, we transfer all equipment to the reserve at any time. The most important thing is that any employee with the appropriate level of tolerance can do this: the processes are debugged sufficiently to not depend on a specific executor - we are so confident in this regard.



However, not only we: the quality control process of DT during certification at the Uptime Institute attracted the attention of the organization’s auditors, who took note of it as industry best practices.