Gasoline
Octane is a number you buy. Vapour pressure is a number that buys you.
Finished unleaded gasoline to EN 228 and the components that make it — quoted on octane, on the seasonal vapour pressure class the destination actually enforces, and on the oxygenate content that decides whether your blend is legal when it arrives.
The desk
Most gasoline disputes are seasonal, not chemical.
Gasoline is bought on octane, and octane is the easy part — it is one number, it is well understood, and both sides can measure it. The parcels that cause trouble are almost never off on RON.
They are off on vapour pressure, because vapour pressure is not a single limit. It is a class, the class changes with the season, the season changes with the country, and a cargo blended for a summer class arriving into a winter market is either non-compliant or a giveaway. The same is true of oxygenate content: a parcel that is legal as E10 in one jurisdiction is not legal where the pump grade is E5, and the oxygen limit is what binds, not the ethanol number.
So we quote the grade with the edition, the vapour pressure class, the oxygenate content and — where you intend to blend downstream — the headroom you have left on benzene, aromatics, olefins and oxygen. Those four ceilings are what turn a cheap component into an unusable one.
The standard
EN 228, and why the edition matters.
The European specification for unleaded petrol. It has been revised repeatedly as ethanol content and vapour pressure rules moved, so "to EN 228" without a year is an incomplete term. We state the edition we are quoting to and the edition your contract fixes, and where they differ we say so before fixture.
| Parameter | Limit | What it governs |
|---|---|---|
| Research octane number | 95 min for the base grade | Knock resistance under load. The headline number and the price driver. |
| Motor octane number | 85 min | The second octane test, at higher engine severity. A parcel can pass RON and be marginal on MON — both are specified for a reason. |
| Sulphur | 10 mg/kg max | Catalyst and aftertreatment protection. Effectively an on/off compliance line. |
| Benzene | 1.0 % v/v max | A health limit, and the tightest constraint on how much reformate a blend can carry. |
| Aromatics | 35 % v/v max | Octane comes cheaply from aromatics, and this is the ceiling that stops you using them. |
| Olefins | 18 % v/v max | Limits FCC gasoline in the blend; also bears on storage stability and gum. |
| Oxygen content | 2.7 % m/m or 3.7 % m/m | The two pathways that separate an E5-type blend from an E10-type blend. This is the real limit — the ethanol figure follows from it. |
| Lead / manganese | 5 mg/l / 2 mg/l max | Metallic additives. Worth testing on any parcel of uncertain history. |
| Oxidation stability | 360 minutes min | Whether the parcel survives storage. Matters most on olefin-rich blends and long voyages. |
| Washed gum | 5 mg/100 ml max | Deposit-forming material. The companion test to oxidation stability. |
| Copper corrosion | Class 1 | Corrosivity as presented. |
| Final boiling point | 210 °C max | Keeps heavy tail out of the blend. Part of the distillation set, with the E70 / E100 / E150 evaporation points. |
Octane
Two numbers, and the gap between them.
RON is measured under mild conditions, MON under severe ones. Both are specified because engines see both, and a blend can be strong on one and weak on the other depending on what it was built from.
The difference between them is sensitivity. Aromatic-rich blends tend to show a wide RON–MON gap; paraffinic and alkylate-rich blends a narrow one. Two parcels can both certify at RON 95 and behave differently in a hot, highly loaded engine, and the sensitivity is where that shows.
It also matters commercially. If you are buying to a RON target and blending down with a low-octane component, the MON floor often binds before the RON target does — which is exactly the kind of thing worth knowing before you fix, not after.
Anti-knock index. Markets outside Europe frequently quote (RON+MON)/2 rather than RON. An "87 octane" grade in an AKI market and a "RON 91" grade are not far apart; an "octane 95" enquiry with no basis stated is ambiguous by roughly four numbers. We ask which basis you mean rather than assuming, because assuming is how a parcel ends up two grades away from what was wanted.
Vapour pressure
A class, not a limit.
EN 228 sets vapour pressure by class rather than by a single number, spanning roughly 45 to 100 kPa across the classes. Which class applies depends on the country and the period of the year, and member states differ. This is the single most common source of a rejected or repriced gasoline cargo.
| Point | Why it bites |
|---|---|
| Summer classes are tighter than winter classes | Volatility is restricted in warm months to control evaporative emissions. A winter-grade parcel delivered into a summer window is off-specification even though nothing about it changed. |
| The transition dates are national | The date on which a market switches class is set locally. A voyage that crosses the switch can load compliant and discharge non-compliant. |
| Ethanol raises vapour pressure non-linearly | Splash-blending ethanol into a base gasoline lifts vapour pressure by more than a volumetric average suggests, and the effect peaks at low ethanol percentages. A base blended to sit just inside a class will breach it once ethanol goes in — so the base needs headroom deliberately built in. |
| Vapour lock index travels with it | Where a market specifies VLI, it constrains vapour pressure and the light distillation points together. Meeting the vapour pressure class alone does not settle it. |
Oxygenates
The oxygen limit binds. The ethanol number is downstream of it.
Almost every gasoline conversation about ethanol is really a conversation about oxygen. EN 228 caps oxygen by mass and then caps each oxygenate individually, so a blend can be within its ethanol limit and still fail on oxygen once other ethers are counted.
| Oxygenate | Indicative EN 228 ceiling | Note |
|---|---|---|
| Ethanol | 5 % v/v on the 2.7 % m/m oxygen route; 10 % v/v on the 3.7 % m/m route | The E5 / E10 distinction in practice. Which one applies is a destination question, not a product question. |
| Methanol | 3 % v/v | Requires stabilising co-solvent. Treated with care and declared explicitly — an undeclared methanol content is a serious defect, not a blending detail. |
| Ethers with five or more carbons | 22 % v/v | MTBE and ETBE. High octane, and they do not carry ethanol's vapour pressure or water-sensitivity problems — which is why they remain valuable. |
| Iso-butanol / tert-butanol | 15 % v/v | Available routes to oxygen where the ethanol limit is already used up. |
Components
What a gasoline is actually made of.
We supply finished grades and we supply components. The components are where the technical conversation happens, because each one buys octane at the price of a different ceiling.
| Component | Brings | Costs you |
|---|---|---|
| Reformate | High octane, cheaply. | Aromatics and benzene. Usually the first ceiling a blend hits. |
| FCC gasoline | Volume and reasonable octane. | Olefins, sulphur and storage stability. |
| Alkylate | High octane with low sensitivity, no olefins, no aromatics, low vapour pressure. The premium blendstock. | Price and availability. |
| Isomerate | Clean light octane from light naphtha. | Modest octane gain; vapour pressure contribution. |
| Light naphtha | Volume and cheapness. | Low octane, and it pushes vapour pressure up. See Naphtha. |
| MTBE / ETBE | Octane and oxygen without ethanol's water sensitivity. | The ether and oxygen ceilings; and MTBE is restricted in some jurisdictions. |
| Butane | Cheap octane and volume. | Vapour pressure, immediately. The classic way to make a summer-grade parcel non-compliant. |
Supply
What we supply.
Finished unleaded, RON 91 to 98
To EN 228 or to the destination's national specification where it differs, with the vapour pressure class and oxygenate content stated on the offer.
Blend components
Reformate, alkylate, isomerate, FCC gasoline and ethers, quoted with the full ceiling set so you can model the blend rather than guess at it.
Parcels and basis
Clean-product tankers into a buyer's terminal, FOB, CFR, CIF or delivered. Dedicated clean tankage and a three-cargo history as standard.
Scope
Where our obligation ends.
- We supply cargo parcels
- Seaborne and, where the trade supports it, delivered into a nominated terminal. We are not a retail supplier and we do not operate service stations.
- We do not blend to order at the terminal
- We do not operate blending terminals. Where a parcel needs a component added to reach your grade, that is your terminal's operation and we will quote the component rather than imply we can perform the blend.
- Additive packages
- Detergent and performance additive dosing is a downstream operation, normally to a brand's own formulation. We will state whether a parcel is additised or unadditised; we will not imply a brand package we have not dosed.
- Compliance at destination
- The applicable grade, class and oxygenate rules at the discharge market are the buyer's to hold. We will flag the ones we know of and we will not quote around a restriction we can see.
How to specify
Six lines and we can price it.
Gasoline enquiries arrive as "RON 95, 30,000 tonnes". These six make that answerable.
Octane, and on which basis
RON, MON or AKI. Say which, and give the MON floor if your market sets one.
Discharge market and window
Which country, which month. This is what determines the vapour pressure class, and it cannot be inferred.
Oxygenate position
E5 or E10 equivalent, whether ethanol is already in or to be added downstream, and whether ethers are acceptable.
Blending headroom you need
If you intend to blend, say what you will add. We will quote the ceilings on benzene, aromatics, olefins and oxygen so you keep room.
Quantity, parcel size and basis
Tonnes or cubic metres, FOB / CFR / CIF / delivered, and whether one cargo or a term programme.
Terminal and tankage
Receiving tankage, vapour recovery, and whether the tank has held ethanol-bearing product before.
Quality
Sampled without losing the light ends.
Independent inspection for the cargo — SGS, Bureau Veritas or Intertek — instructed jointly, sampling under supervision at a point agreed before the vessel arrives, with the quality and quantity determination points named separately in the contract.
On gasoline the sampling method is part of the specification, because a sample that vents loses exactly the light material that vapour pressure measures. A vapour pressure result obtained from a carelessly handled sample reads low, in the direction that flatters the cargo.
- Core test set
- RON and MON; density at 15 °C; vapour pressure with the method and class stated; full distillation with the evaporation points; sulphur; benzene; total aromatics and olefins; oxygen content and individual oxygenates; lead and manganese; oxidation stability; washed gum; copper corrosion; appearance and colour.
- Where we test beyond the table
- Silicon and chloride screening where a parcel's history warrants it. Both are contamination markers rather than routine parameters, and both cause damage far downstream of the tank.
- Ethanol-bearing parcels
- Water content and phase-separation behaviour, plus confirmation of the tank's previous service.
- Retained samples
- Sealed retains at load and discharge, stored so the light ends survive.
- Documentation per parcel
- Certificate of Quality, Certificate of Quantity, Certificate of Origin, safety data sheet in the destination language, bill of lading, three-cargo tank history and the independent inspection report.
Straight answer
What we will tell you before you ask.
- That the vapour pressure class will decide this trade
- More often than octane will. Tell us the market and the month and we will get it right; leave it out and it is the parameter most likely to cost you.
- That octane without a basis is ambiguous
- RON and AKI differ by roughly four numbers. We will ask rather than assume.
- That adding ethanol is not a volumetric calculation
- It moves vapour pressure more than the arithmetic suggests, and it makes the parcel water-sensitive. A base intended for downstream ethanol has to be built for it.
- Where a cheap component is the wrong component
- Butane and reformate both buy octane and both spend a ceiling you may need. If a component would use up your headroom, we will say so instead of selling it to you.
- Where an origin cannot be cleared
- Screened per consignment; declined where it cannot be documented, and not referred onward — see Compliance.
Enquiries
Every enquiry is answered by the desk that handles it.
Send the product, quantity, delivery basis, destination and timing. We revert with availability, an indication and the documentation that accompanies it. Specifications are released once we know who we are speaking with.