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The Preservation Of Diesel Product Integrity

There are many misconceptions about customer diesel supply in South Africa. In this article, we take a look at a follow-up on our Life of Diesel article and delve into the importance of sourcing and using quality diesel products.

As the driving force behind the commercial sector in South Africa, diesel fuel is one of the higher-valued light products on the market today. This presents both challenges and opportunities within the diesel fuel supply chain. It is at the hand of this network that challenges for creating value for the customer exists. Your fleet and equipment are a huge investment for your business, and that is why it is important to ensure that customers know how to check the quality of their diesel fuel, as well as the correct storage and housekeeping methods. 

Covered in this article:

Quality control
Analysing diesel colour
The importance of good housekeeping

Quality control

Controlling the quality of diesel supply can be a challenge.
A fair proportion of diesel engine failures can be directly traced back to the quality of the fuel which was in use. Fuel contamination, degradation or adulteration can have serious issues that can arise if quality control is not asserted over the diesel used.

The deliberate addition of off-specification fuel or contaminants can occur during distribution and is difficult to identify unless the fuel is analysed or the fuel quality is carefully monitored. To curb this, it is important to always purchase fuel from registered SAPIA distributors.

The quality of diesel fuel is determined by:

  • Sulphur content: Diesel fuel contains sulphur which derives from the original crude oil source and can still be present after refining. After combustion in the engine, the sulphur in fuel forms particulates that are a primary contributor to air pollution and the cause of harmful corrosion in the engine.

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  • Cetane number: The cetane number is a measure of the so-called ignition delay of diesel fuel. This is the period between the point at which the fuel is injected into the combustion chamber and the start of combustion. It is an industry-standard measure for evaluating a diesel fuel’s combustion quality. Fuels with a high cetane number (shorter ignition delay) tend to deliver smoother and quieter engine operation. Cetane number is the most important and universally accepted ignition quality test. The cetane number test uses a standard single cylinder variable compression ratio diesel engine. The cetane index is a calculated value, which is derived from relatively easily measured fuel properties.

  • Flash point: In fuel, the flash point is the lowest temperature at which the application of the ignition source causes the vapours above the liquid to ignite. The flash point of diesel fuel is between 52 to 82 degrees Celsius.Diesel-Contamination-Test

  • Pour point: Pour point is an important quality specification for diesel fuels. Specifically, it is a measure of the tendency of a fuel to become more viscous and resist flowing when cold. 

  • Cloud point: When looking into the quality of your diesel, the term cloud point will surface. This refers to the temperature below which wax in diesel or bio wax in bio-diesels forms a cloudy appearance. The presence of solidified waxes thickens the oil and clogs fuel filters and injectors in engines.

Understanding the building blocks of a quality fuel can improve decision-making. Using premium diesel can improve engine efficiency and longevity. Astron Energy fuels are designed to deliver lower emissions, higher performance, and a cleaner engine. 

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Analysing diesel colour

There is a commonly held perception to equate diesel colour with performance – the darker, the better, as some would say. As a result, some believe that if the product is unusually pale, there must be an issue with the quality. This perception is more prevalent in the commercial and industrial sectors because, unlike retail, they are more exposed to fuel theft and product adulteration.

The colour of diesel, provided it is not contaminated or adulterated, has no bearing on its quality or fitness-for-purpose. When freshly manufactured, its colour may vary. A pale yellow or “straw” colour is typical, although it may have a greenish tinge and exhibit a slight fluorescence under good lighting conditions.

Lab examination

A fuel analysis looks at the state of the product in terms of certain problems which may have occurred since the fuel left the refinery. This can be done in an accredited laboratory that specialises in fuel testing. The speculative fuel samples are tested against SANS 342:2014 specifications, which is the standard specification for diesel in South Africa.

The Preservation Of Diesel Product Integrity

The importance of good housekeeping

Improper handling, transportation or storage of these fuels can lead to deficient quality of the fuel. Contamination by water, sediment, inorganic contaminants, or microbial growth
may occur at any link within the supply chain, especially during storage. Addressing this does not require budgeting for specialised machinery, technology or staff. Rather, these issues can be curbed by adopting a better maintenance strategy.

It is key that storage tanks are consistently monitored, to ensure that the diesel is still fit for purpose. To assist with this, many storage tanks are designed with bottom valves allowing to periodically drain off water. Other checks that should be regularly included: maintaining seal integrity; ensuring filters are unclogged; and proofing the tank for any damage that could cause leakage. Tanks should always be kept relatively full if not used for prolonged periods of time, with only a small air space above the fuel line to minimise condensation of air humidity and corrosion.

Here are three housekeeping tips:

1. Implement regular staff training around fuel housekeeping best practices, emphasising the efficiency and performance consequences of poor fuel storage and handling. An example of this would be the proper cleaning and draining of sludge and water from bulk tanks and mobile fuel carts.

2. Above and beyond the mass storage of diesel, it is equally important to pay attention to the management of engine-driven equipment. Some best practices are to ensure that equipment and fuel tanks are refuelled when they are stored to reduce the risk of condensation and water forming inside the tank.

3. Customers should consider doing regular fuel tests from bulk and mobile fuel storage tanks, as well as their engine-driven equipment. Fuel samples should be taken in glass bottles or tin cans and should be taken at the right levels.

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At Astron Energy, we believe that great business partnerships create shared value, sustainable growth and real transformation. Our extensive depot network across South Africa, backed by our manufacturing and import capability, ensures reliable supply 100% of the time. That's why we don’t just provide premium fuels and lubricants to optimise your organisation’s performance, we also offer a range of specialist knowledge to improve business efficiencies, and maximise operating time while minimising costs. Our specialists will gladly assist with any technical questions or queries you or your business might be facing, so contact us today.