🧫 Distillation of Petroleum Products

Petrochemistry PN-EN ISO 3405

Overview

STATUS (as of 30.10.2026). PN-EN ISO 3405:2019-05 — Polish and English versions, implements EN ISO 3405:2019 and ISO 3405:2019 [IDT]; the Polish version was published on 09.10.2020 and replaced PN-EN ISO 3405:2012 (which implemented ISO 3405:2011). ISO 3405:2019 is the fifth edition of the standard, published on 22.03.2019; ISO confirmed it on 30.07.2024 and decided on 14.03.2025 to revise it — the draft of the sixth edition (ISO/FDIS 3405) has been at the approval stage (FDIS ballot) since 28.10.2026. Until the new edition is published, the 2019 edition applies.

SCOPE (clause 1). Laboratory determination of the distillation characteristics of light and middle distillates derived from petroleum and of related products of synthetic or biological origin, with initial boiling points above 0 °C and end points below approximately 400 °C, using manual or automated apparatus. Light distillates are typically automotive engine petrol, automotive engine ethanol fuel blends with up to 85 % (V/V) ethanol, and aviation petrol; middle distillates — aviation turbine fuel, kerosene, diesel, diesel with up to 30 % (V/V) FAME, burner fuel and marine fuels that have no appreciable quantities of residua. The distillation (volatility) characteristics have an important effect on safety and performance, especially of fuels and solvents: the boiling range gives information on composition and on behaviour during storage and use, the rate of evaporation matters in the application of many solvents, and limiting values of distillation characteristics are applied in most distillate petroleum product and liquid fuel specifications — to control end-use performance and to regulate the formation of vapours which may form explosive mixtures with air or otherwise escape into the atmosphere as volatile organic compounds (VOC). The corresponding American standard ASTM D86 (5.3) adds that the distillation characteristics of automotive and aviation gasolines affect starting, warm-up and the tendency to vapour lock, and that the presence of high-boiling components affects the formation of solid combustion deposits.

PRINCIPLE AND TERMS (clauses 3–4 of draft ISO/DIS 3405:2017; definitions as in the 2000 edition). The sample is assigned to one of four groups based on its composition and expected volatility; the group defines the apparatus arrangement, the condenser temperature and the other operating conditions. A 100 ml test portion is distilled under the conditions appropriate to the group, with systematic observations of thermometer readings and of volumes of condensate recovered; the volume of the residue in the flask is measured and the loss is recorded, and the thermometer readings are corrected for barometric pressure. The initial boiling point is the corrected reading at the instant the first drop of condensate falls from the lower end of the condenser tube; the end point (final boiling point) — the maximum corrected reading obtained during the test; the dry point — the reading at the instant the last drop of liquid evaporates from the lowest point in the flask (the end point is intended for general use; the dry point can be reported, for example, for special purpose naphthas used in the paint industry). The percent recovered is the volume of condensate in the cylinder at a given moment as a percentage of the charge volume; the loss is 100 minus the total recovery (recovery and residue), and the percent evaporated — the sum of the percent recovered and the percent loss.

APPARATUS AND EDITION CHANGES (5.1–5.4 and the foreword of draft ISO/DIS 3405:2017, from which the 2019 edition was developed). Distillation flasks of 125 ml capacity made of heat-resistant glass; condenser tube of seamless non-corrosive metal tubing, (560 ± 5) mm long, with an outside diameter of 14 mm and a wall thickness of 0.8 mm to 0.9 mm, with (393 ± 3) mm in the cooling medium and an average gradient of 15° ± 1° with respect to the horizontal; in manual apparatus a flask shield. Automated apparatus measure and record the vapour temperature and the recovered volume, and those manufactured in 1999 and later have a device that, in the event of fire, shuts down power and sprays an inert gas into the flask chamber. According to the foreword of the draft, the 2019 edition extended the scope to synthetic and biological products, and specifically to automotive ethanol fuel blends and B30 diesel, aligned the procedure with ASTM D86, updated the precision for automated apparatus in groups 1–3 (slope-based, from a 2010 interlaboratory study) and for T95 in group 4 (range 260 °C to 360 °C), and introduced a solution for replacing mercury-in-glass thermometers.

HOW THE TEST IS PERFORMED — ACCORDING TO THE 2000 EDITION (ISO 3405:2000, in Poland PN-EN ISO 3405:2004; the procedure of the current edition is not known to us; that edition divided samples into five groups, 0 to 4, the current one into four). Groups (Table 1): 0 — natural gasoline; 1 — gasolines with a Reid vapour pressure of at least 65.5 kPa and a final boiling point up to 250 °C; 2 — gasolines with a vapour pressure below 65.5 kPa and a final boiling point up to 250 °C; 3 — wide-cut aviation fuel (initial boiling point up to 100 °C, final above 250 °C); 4 — kerosine and gas oil (initial boiling point above 100 °C, final above 250 °C). Samples of groups 1 and 2 are collected in containers cooled below 10 °C and kept below 10 °C — where this is not possible, up to 20 °C, but they are always conditioned below 10 °C before the container is opened. Samples that visibly contain water are not suitable for testing: in groups 0–2 another sample is obtained and, if that is not possible, the water is removed with anhydrous sodium sulfate and the drying is recorded; in groups 3–4 the water is removed with sodium sulfate and decantation. At the start, the flask, thermometer, cylinder and sample are at 13–18 °C (groups 1–3); in group 4 the cylinder and sample are between 13 °C and ambient temperature (Table 2). The test portion is measured to the 100 ml mark of the cylinder, which then receives the distillate without drying; if irregular boiling is expected, clean and dry boiling chips are added. Conditions (Table 3): condenser bath 0 °C to 1 °C (groups 0–1), 0 °C to 4 °C (groups 2–3), 0 °C to 60 °C (group 4); time from first heat to the initial boiling point 5–10 min (groups 1–3) or 5–15 min (group 4); from the initial boiling point to 5 % recovered 60–100 s (groups 1–2); from 5 % recovered to 5 ml residue in the flask a uniform average rate of 4–5 ml/min; from 5 ml residue to the final boiling point not more than 5 min. A distillation that does not meet these conditions is repeated. Where no other requirements are given, the following are recorded (groups 1–4): the initial and final boiling point or the dry point, and readings at 5 %, 15 %, 85 %, 95 % and every 10 % recovered; volumes to the nearest 0.5 ml or 0.1 ml, temperatures to 0.5 °C or 0.1 °C, depending on the apparatus. In this edition the manual procedure was the referee method unless otherwise agreed (clause 1); this sentence is not in the scope of the 2019 edition.

CALCULATIONS AND RESULT — ACCORDING TO THE 2000 EDITION (clauses 9–12). The recovery is recorded when two successive readings at 2 min intervals agree (manual apparatus) or when the volume changes by no more than 0.1 ml in 2 min (automated apparatus); the residue — after the flask has cooled, in a 5 ml cylinder to the nearest 0.1 ml; loss = 100 − (recovery + residue). The thermometer readings are corrected to 101.3 kPa with the Sydney Young equation: Tc = 0.000 9 · (101.3 − pk) · (273 + t), where pk is the pressure in kPa and t the reading in °C; the absolute value of the correction is added when the pressure is below 101.3 kPa and subtracted when it is above. The loss is corrected with Lc = 0.5 + (L − 0.5) / [1 + (101.3 − p) / 8.00]. For groups 0 and 1, or with a loss exceeding 2.0 % (V/V), the relationship between temperature and percent evaporated is reported, for groups 2–4 — between temperature and percent recovered. The precision in this edition depends at most points on the slope of the distillation curve (change of temperature per 1 % volume; 12.1, Tables 5–8).

WHAT WE DO NOT GIVE HERE. The procedure, calculations and conditions of the 2019 edition (in draft ISO/DIS 3405:2017 separate procedures for manual and automated apparatus — clauses 9 and 10), including the limits of the four current sample groups and the requirements for sensors replacing mercury-in-glass thermometers, or the precision values of the 2019 edition (clauses 13 and 14 of the draft) — we only know clauses 1–4 and 5.1–5.4 of draft ISO/DIS 3405:2017.

Method principle

A 100 ml test portion is distilled in a standardized flask under the conditions appropriate to the group to which the sample belongs (condenser temperature, distillation times and rate), with systematic observations of the vapour temperature in the flask neck and of the volumes of condensate collected in the cylinder.

After the distillation the volume of the residue is measured and the loss is calculated; the temperature readings are corrected for barometric pressure, and the data are used for the calculations appropriate to the nature of the sample and to the specification requirements.

Applications

• Light distillates — automotive engine petrol, automotive engine ethanol fuel blends with up to 85 % (V/V) ethanol, aviation petrol (clause 1)
• Middle distillates — aviation turbine fuel, kerosene, diesel (also with up to 30 % (V/V) FAME), burner fuel, marine fuels without appreciable quantities of residua (clause 1)
• Automotive petrol — the Polish regulation on quality requirements for liquid fuels (requirements based on PN-EN 228+A1:2017-06) specifies the volume evaporated at 70 °C (E70), 100 °C (E100) and 150 °C (E150), a final boiling point of at most 210 °C and a residue of at most 2 % (V/V) (Dz.U. 2024 item 1018, Annexes 1 and 2, No 16–18)
• Diesel fuel — distillation according to that regulation (based on PN-EN 590:2022-08): less than 65 % (V/V) recovered at 250 °C, at least 85 % (V/V) at 350 °C, 95 % (V/V) recovered by 360.0 °C; diesel with improved low-temperature properties: at most 10.0 % (V/V) at 180 °C, at least 95.0 % (V/V) at 340 °C (Annex 3 No 18)
• Input data for calculating the cetane index according to PN-EN ISO 4264 — the 10 %, 50 % and 90 % (V/V) recovery temperatures (ISO 4264:2018, 5.2)
• Special purpose naphthas, for example those used in the paint industry — the dry point can be reported (3.2)

Key parameters

Standard

Standard number

PN-EN ISO 3405:2019-05

Title (PL)

Przetwory naftowe i produkty podobne pochodzenia naturalnego i syntetycznego — Oznaczanie składu frakcyjnego metodą destylacji pod ciśnieniem atmosferycznym

Title (EN)

Petroleum and related products from natural or synthetic sources — Determination of distillation characteristics at atmospheric pressure

Step-by-step procedure

1. Sample group and sampling

   Assignment of the sample to a group according to composition and volatility (currently four groups). 2000 edition (clause 6, Table 1): gasolines in containers cooled below 10 °C; a sample with visible water is resampled or dried.

2. Preparation of apparatus

   2000 edition (clause 7, Table 2): flask, sensor and flask-support board according to the group; flask, sensor, cylinder and sample at 13–18 °C (groups 1–3), in group 4 cylinder and sample between 13 °C and ambient temperature; residual liquid is removed from the condenser tube with a soft, lint-free cloth attached to a cord or wire.

3. Measuring the test portion

   The test portion is measured to the 100 ml mark of the receiving cylinder and transferred to the flask so that no liquid flows into the vapour tube; the same cylinder, without drying, is placed under the condenser outlet (2000 edition, 7.5–7.8).

4. Distillation

   2000 edition (9.1–9.5, Table 3): from first heat to the initial boiling point 5–10 min (groups 1–3) or 5–15 min (group 4); from 5 % recovered to 5 ml residue on average 4–5 ml/min; from 5 ml residue to the final boiling point not more than 5 min; a distillation not meeting these conditions is repeated.

5. Readings

   Initial boiling point, temperatures at the required percentages recovered, final boiling point or dry point. 2000 edition (9.7.2): where no other requirements are given — at 5 %, 15 %, 85 %, 95 % and every 10 % recovered.

6. Recovery, residue, loss

   2000 edition (9.10–10.1): recovery when two successive readings at 2 min intervals agree (manual apparatus) or the volume changes by no more than 0.1 ml in 2 min (automated), residue from the cooled flask in a 5 ml cylinder to the nearest 0.1 ml, loss = 100 − (recovery + residue).

7. Correction and result

   2000 edition (10.2–10.3, clause 11): readings are corrected to 101.3 kPa (Tc = 0.000 9 · (101.3 − pk) · (273 + t)), the loss — with Formula (3); the result states the sampling procedure and the procedure used: manual or automated.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Use of the standard can involve hazardous materials, operations and equipment — safety measures are established by the user (warning of the standard)
• Causes of fire include breakage of the flask, electrical shorts, and foaming and spilling of liquid sample through the top opening of the flask — automated apparatus since 1999 have automatic power shutdown and inert gas injection (5.1)
• A tightly sealed, full, cold container of sample is likely to break if heated (2000 edition, caution in 6.2.3)
• The bulb of a mercury-in-glass thermometer can be 28 °C above the indicated temperature — readings above 371 °C should be avoided, and a thermometer that has shown them is checked at its ice point before re-use (2000 edition, 5.8.1)
• In manual apparatus the flask shield protects the operator in case of damage to the unit and the flask from draughts (5.4)

Frequently asked questions