LPG Analysis — EN 589 / EN 267 / Autogas and Cylinder Gas

What Is LPG?

LPG analysis is the determination of the composition and quality parameters of propane, butane and their mixtures. Hydrocarbon composition is measured by gas chromatography, along with vapour pressure, evaporation residue, total sulfur, hydrogen sulfide, copper strip corrosion, free water, and motor octane number for autogas.

Purpose of LPG

The purpose is to verify that the LPG shows evaporation behaviour suited to its intended use, is not corrosive, and does not leave residue in equipment.

Which Products Is LPG Applied To?

Autogas (LPG)
Cylinder gas and bulk LPG
Industrial propane and butane
Refinery LPG streams
Export/import cargo samples

In Which Sectors Is LPG Used?

Oil & GasPetrokimyaEnergyAutomotiveEnergy

Standards Related to LPG

TS EN 589 (automotive fuels — LPG specification)
TS EN ISO 7941 (composition — gas chromatography)
TS EN ISO 4256 / EN ISO 8973 (vapour pressure and density)
TS EN 15470 / EN 15471 (evaporation residue)
TS EN ISO 4260 / EN 24260 (total sulfur)
TS EN ISO 8819 (hydrogen sulfide)
TS EN 15469 (free water)

LPG Conditions

Sampling: With pressurized sample tubes; Filling ratio in accordance with the standard must be maintained
Engine octane number: Calculated from composition (MON)
Residue: Evaporation residue is indicative of injector blockage
Safety: Sample tubes are pressure vessels; subject to transport rules

Equipment for LPG

Gas chromatograph (LPG composition analysis)
Pressurised sample cylinders and filling setup
Vapour pressure measurement apparatus
Evaporation residue setup
Sulfur analyser

Sample Requirements for LPG

A pressurised sample cylinder must be used; the fill ratio must comply with the standard
The sample cylinder must be shipped per pressure vessel transport rules
The sampling point, date and temperature must be recorded
Cylinder valves must be leak-tight

Duration of LPG

Composition and vapour pressure analyses are completed quickly. The full package, including evaporation residue and sulfur analyses, takes a few working days.

LPG Procedure

1The pressurised sample cylinder is received and its identity verified.
2Hydrocarbon composition is determined by gas chromatography.
3Vapour pressure and density are measured.
4Evaporation residue is determined.
5Sulfur, hydrogen sulfide and corrosion tests are performed.
6MON is calculated and results compared against the specification.

LPG Acceptance Criteria

The acceptance criterion comes from the relevant product specification and varies by season, market and class. Specification versions are updated; the limit values in force for your product are confirmed from the specification text at the quotation stage.

Evaluation of Results

Evaporation residue is the parameter causing the most frequent problems in autogas: high residue builds up deposits in the injector and regulator. Composition determines seasonal behaviour; a high butane ratio in winter hinders evaporation and causes cold-start problems.

LPG Report

Sample description, cylinder number and sampling information
Hydrocarbon composition
Vapour pressure and density
Evaporation residue and sulfur results
Calculated MON
Comparison against specification limits

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

98/70/EC Fuel Quality Directive

Petroleum, Fuel and Oil Analysis — What Does This Testing Field Cover?

The section below describes the field that the LPG test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Petroleum, fuel and oil analysis determines whether a fluid meets its specification and how it behaves in use. Standards in this field consist largely of ASTM and EN publications, with a separate method defined for each parameter.

What distinguishes this family is that product specifications are written as PARAMETER LISTS. Specifications such as EN 590 (diesel), EN 228 (petrol), EN 14214 (biodiesel) and ISO 8217 (marine fuels) state for each parameter both the limit and the method by which that limit is to be measured. If the method changes the result may change too; the specification therefore binds the method as well, and the use of an "equivalent method" is possible only where the specification allows it.

On the fuel side, parameters describe three different properties of the product. Physical properties (density, viscosity, distillation curve, pour point, cloud point) determine pumpability and cold weather behaviour. Combustion properties (cetane number, octane number, calorific value) indicate performance in the engine. Contaminant and stability parameters (sulphur, water, sediment, oxidation stability, copper strip corrosion) affect both emissions and storage life.

Oil analysis is carried out for two different purposes and the two must not be confused. Analysis of NEW oil verifies the conformity of the product to its specification: viscosity index, additive content, flash point. Analysis of USED oil, by contrast, is done to read the condition of the machine — elemental analysis shows wear metals (iron, copper, chromium, aluminium), water and fuel contamination point to leaks, and oxidation and acid number determine the remaining life of the oil.

Used oil analysis is therefore a PREDICTIVE MAINTENANCE tool. The trend of samples taken at regular intervals is followed; it is the trend rather than a single result that is meaningful. Iron levels climbing over the course of months allow intervention before a failure occurs.

Marine fuels are the most active sub-body of the field. The global tightening of sulphur limits has brought new blended fuels onto the market; for these fuels stability, compatibility (whether two fuels form deposits when mixed) and catalytic fines content have become critical parameters.

Sampling is part of the result in this family too. A sample taken from the bottom of a tank shows different water and sediment content from one taken from the upper level; in commercial deliveries the sampling point and method are set by contract.

Method groups in this field

Physical properties
Density (oscillating U-tube and hydrometer), kinematic viscosity, distillation, pour and cloud point, flash point.
Combustion properties
Cetane number and cetane index, research and motor octane number, calorific value.
Sulphur and elements
Sulphur by UV fluorescence and XRF; elemental analysis and additive content by ICP.
Stability and corrosion
Oxidation stability, copper strip corrosion, water and sediment, filter blocking tendency.
Composition analysis
Boiling range distribution by gas chromatography, hydrocarbon types (FIA), benzene and aromatics content, fatty acid methyl ester content.
Used oil
Wear metals, contamination (water, fuel, soot), oxidation, acid and base number, change in viscosity.

Commonly confused in this field

The specification binds the method as well; a result measured by a different method may not be accepted for specification conformity.
A single result on used oil is not meaningful; the decision is made on the trend.
The sampling point determines the result; the tank bottom and the upper level show different water and sediment.
The cetane index is a calculated value and is not the same thing as a measured cetane number.
Fuels blended with biodiesel behave differently in terms of storage life and microbial growth; classical diesel parameters are not sufficient.
Mixing marine fuels from different sources can cause deposits; compatibility is assessed separately.

Which decisions these results support

Conformity of a fuel lot to specification and commercial delivery
Predictive maintenance decisions based on used oil analysis
Determining parameters for customs and tax classification
Quality verification after storage, blending and transport
Compliance with sulphur limits under emissions legislation

Related Tests

Frequently Asked Questions About LPG

The vehicle struggles to run in winter — could it be the LPG?

It could be. A mixture with a high butane ratio does not evaporate sufficiently at low temperature. Composition analysis and vapour pressure measurement directly show this.