In this blog article, our Midlands Area Sales Manager Martin Arden explains in detail ‘what is 35 second oil’ and how this type of oil is used within heating systems.
What is 35 second oil?
Also known as Gas Oil’, or Red Diesel’, 35 Second oil is used for commercial boiler, generator, agricultural, and vehicle fuel. 35 second Gas oil suitable for use in heating appliances should meet BS2869: Part 2 : 2010 classifications Class D.
The Fractionating column diagram below shows how crude oil is separated into its component parts producing various fuels for use in transport and industry, one of which is Diesel oil, of which 35 second is a type.
Image by [Dmitry Sokolov – http://confocal-manawatu.pbworks.com/w/page/101875267/Fractional%20distillation
What does 35 second oil look like?
35 Second diesel oil has a clear and bright, cherry red appearance, without sediment and has a lower cost than car diesel fuel, as it has low or rebated tax relief, making it illegal to be used on the road. The red appearance enables it to be differentiated from diesel used in cars, heavy penalties are applied if caught using 35 Second on road-going vehicles.
The `Sec’ denotes a measure of a hydrocarbon fuel viscosity and is expressed as the number of seconds 50ml of fuel takes to flow under controlled conditions, through a set size orifice. This testing equipment is known as the Redwood Viscometer.
The fuel in the holding cup is heated to 40 degrees C,and once conditions are correct, time is started and the oil allowed to passthrough the orifice, once through, the time is stopped, and the number ofseconds recorded.
The longer the time taken, the thicker the oil and thehigher the viscosity. Gas oil is one of the thicker oil types used in heatingappliances which can vary from 28 Sec to 35 Sec.
Low temperature and best storage practice
When being stored or fired viscosity is affected by the ambient temperature, due to its thicker nature 35 Sec oil is susceptible to clouding in cold ambient conditions and can gel or wax a few degrees below the cloud point temperature. Although the cloud point temperature can vary due to local conditions any temperature below zero may result in clouding. This will, of course, reduce the flow of oil and render the heating appliance redundant, as a way of reducing this some burners have a preheater to ensure constant flow. Another option is to insulate any above-ground supply pipework.
Below diagram shows a typical oil storage installation.
Image by http://www.telfordtanks.co.uk/installations.asp
In the UK, often the perceived issue of waxing is incorrect, and can often be attributed to condensation or moisture having formed in the storage tank, this can easily freeze causing the effect of waxing.
Oil Combustion
35 Sec Class D oil burns hotter than other oils and has a nett calorific value of 10.85 kwh per litre or 36.28mj per litre, but has a relatively high sulphur content in comparison to other fuels up to a maximum of 1000ppm. Lower sulphur content versions of 35 Sec oil are available, the A2 version is used for agricultural vehicles and has a 10ppm sulphur content but is not recommended for a boiler/burner applications. Other variants are also available but care should be taken as burner manufacturers will not always uphold warranty claims.
The liquid oil in itself does not burn, it is the vapour it creates which is combustible. This is achieved by pressurizing the fuel through a pump and a high-pressure jet nozzle, which in turn vaporizes or mists the oil causing it to ignite when mixed with the correct amount of air and a spark.
The schematic diagram below shows typical componentsand the combustion process for a pressurized burner.
Image by http://www.telfordtanks.co.uk/installations.asp
Typical oil pressures are high to enable vapourization,in the region of 200psi, and these burners should only be worked on by suitablyqualified engineers.
Environmental concerns over airborne pollutants make the future of Class D type 35 Sec oil uncertain, less environmentally harmful options are now available and conversions are taking place. As the cost of Gas oil is now also higher than these alternatives, new appliances are also being manufactured to suit the cheaper fuels.
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FAQs
Also known as Gas Oil', or Red Diesel', 35 Second oil is used for commercial boiler, generator, agricultural, and vehicle fuel. 35 second Gas oil suitable for use in heating appliances should meet BS2869: Part 2 : 2010 classifications Class D.
What does 35 second oil mean? ›
'28-second oil' is used as a term to distinguish kerosene's viscosity, through a specific test of how long it takes 50ml of the oil to drip into a beaker. The same test is also used for gas heating oil also known as red diesel or '35-second oil', this is usually used in older boilers, agriculture or commercially.
What is the meaning of 28 second oil? ›
The term '28-second oil' is used as a term to distinguish kerosene's viscosity, through a specific test of how long it takes 50ml of the oil to drip into a beaker. This also explains how red diesel gets its '35-second' name.
What is Therma 35 heating oil? ›
Therma35 is a drop-in alternative to conventional Class A2 gas oil. Ideal for use in commercial boilers, heaters, driers and furnaces. With no equipment modifications required and a long storage life, it's a cost-effective choice for all kinds of businesses.
Can you mix kerosene and home heating oil? ›
While it is best not to mix kerosene and home heating oil, heating systems can typically work with either type. If you need to switch over, this is possible without any additional dangers. Even one-off uses of a different kind of oil may be fine. However, regularly doing this could ruin your appliance.
Is it worth buying premium kerosene? ›
The additives in premium kerosene help your system to work more efficiently, which means you could use less over time. Not only could it save you money, it also lowers the amount of carbon dioxide produced by combustion. Lower carbon dioxide means it is a kinder option for the environment.
What does the second number mean in oil? ›
The first number precedes the letter 'W' which stands for Winter. This measurement is related to how an oil flows when it is cold, such as at engine start-up. The second number is defined by how an oil flows at normal engine operating temperatures. The smaller the number, the better it will flow.
Can I put diesel in my oil tank? ›
Can You Put Diesel in Your Oil Tank? Yes, you can. While waiting for your oil supply delivery, you can substitute diesel for heating oil. Diesel and heating oil can also be mixed if you're running low on oil and are worried about running out.
What is the oil Bible? ›
Oil is a powerful symbol in the Bible, representing divine blessings, protection, healing, and the presence of the Holy Spirit. It has been used in religious practices such as anointing priests and consecrating places. In the Catholic Church, oil is vital to sacraments, providing strength and grace.
Is #1 fuel oil the same as diesel? ›
The only real difference is the higher price. As for home heating applications, diesel can be mixed with #1 fuel oil to minimize sludge formation during cold months.
If your oil tank is inside of your home or business, use heating oil; if it's outside your home or business, use kerosene or a blend of heating oil and kerosene to keep your equipment operating reliably when temperatures are low.
Can I use red diesel instead of kerosene? ›
I live off the gas grid here in Wales and use kerosene in my boiler. The difference? Red diesel has a 35 second viscosity and kerosene has a 28 second viscosity. The fuels are interchangeable but the nozzles on the burner have different specifications and the fuel/air mix ratios are slightly different.
What burns hotter kerosene or diesel? ›
The paraffin/wax content is higher in diesel, and it produces more BTUs (heat) than Kerosene. Kerosene, however, is often used in very cold temperatures, as it doesn't thicken as easily as diesel under these conditions.
Can I use diesel instead of heating oil? ›
Diesel as a Heating Fuel Alternative: Safety and Uses
Once you are sure that you have an oil tank that is at least below critical levels or out of heating oil, you can temporarily use diesel. This alternative is an excellent fuel option but remember that it should only be used for a short period.
Is K1 kerosene safe to burn indoors? ›
The only fuel approved for indoor kerosene heaters is K-1 kerosene. Lesser quality fuels will cause problems (see below).
Does kerosene go bad? ›
Kerosene goes bad over time. When stored properly, it has up to five years of shelf life. This petroleum-based fuel loses its flammable quality when condensation adds water to the storage container over time or mold and bacteria populations transform it into a sludge-like consistency.
What is the best oil interval? ›
It used to be normal to change the oil every 3,000 miles, but with modern lubricants most engines today have recommended oil change intervals of 5,000 to 7,500 miles. Moreover, if your car's engine requires full-synthetic motor oil, it might go as far as 15,000 miles between services!
What does the first and second number on oil mean? ›
In this system, a colon separates two numerals, such as “30:60.” The first value represents the approximate thickness of the oil at low temperatures, while the second number represents the approximate thickness at high temperatures.
How long will 3 inches of oil last? ›
3 inches or 8cm from the bottom of a 1,200 litre tank means you have approximately 100 litres of oil left. That will last the average home between 5-10 days depending on usage.
How much oil is normal to add between oil changes? ›
Some new vehicles today will use a quart of oil every 800 to 1000 miles. That means a driver could have to add as many as five quarts of oil between changes.
