🧵 Flame spread on vertically oriented textile specimens — burner flame applied for 10 s to the surface or bottom edge of a 560 × 170 mm specimen, measurement of the time until three cotton marker threads are severed; PN-EN ISO 6941

Materials and NDT PN-EN ISO 6941

Overview

WHAT THE STANDARD COVERS. ISO 6941:2003 (clause 1) specifies a method for the measurement of flame spread times of vertically oriented textile fabrics and industrial products in the form of single- or multi-component fabrics (coated, quilted, multilayered, sandwich combinations and similar combinations) when subjected to a small, defined flame. According to the introduction, it is one of two closely related methods of test for the inflammability of textile fabrics: this one determines the "flame spread time" (vocabulary according to ISO 4880), the other the "ease of ignition" (ISO 6940; a separate entry in this database). The method assesses the behaviour of the product on flame contact under controlled conditions; the results may not apply to situations with restricted air supply or exposure to large sources of intense heat. The influence of seams can be determined by this method — the seam is placed in the specimen so that it is subjected to the flame; trimmings are tested, whenever practicable, as part of the assembly with which they will be used. Definitions (clause 3): flame application time — the time for which the ignition flame is applied to the specimen; flame spread time — the time taken by a flame on a burning material to travel a specified distance under specified conditions. We read the text of the standard in the iTeh sample of ISO 6941:2003 (English and French text) from the title page through the foreword, introduction and clauses 1–6 (up to 6.3), and in the iTeh sample of ISO 6941:2026 (English and French text) from the title page through the table of contents, foreword, introduction and clauses 1–4.

PRINCIPLE (clause 4). A defined flame from a specified burner is applied for 10 s to the surface or the bottom edge of vertically oriented specimens. The times (in seconds) for the flame front to travel between marker threads stretched just next to the specimen surface at three distances from the igniting flame are recorded. The table of contents of the 2026 edition names both variants: procedure A — surface ignition, procedure B — bottom edge ignition.

APPARATUS (clause 5, 2003 edition). The mounting frame holds the burner and the specimen holder in the relative position of Figure 3 and allows three marker threads to be attached in the positions of Figure 2; each thread forms a loop whose two segments lie 1 mm and 5 mm from the plane of the front surface of the specimen, and each loop is connected to a separate timer. The burner (Figure 1, Annex A) is moved from a standby position — tip at least 75 mm from the specimen — to a horizontal or inclined operating position. Specimen holder: a rectangular metal frame 560 mm × 150 mm with 12 pins along the longer sides, 5, 10, 190, 370, 550 and 555 mm above the bottom edge of the frame, at least 26 mm long (longer ones may be needed for thick or multilayer specimens); next to each pin, except the top and bottom one on each side, a spacer stub of 2 mm diameter and at least 20 mm length — the specimen lies at least 20 mm from the frame. Template: flat, rigid, with the specimen dimensions 560 mm × 170 mm, with 12 holes of about 4 mm diameter at the pin spacing. Gas: commercial grade propane or butane or their mixture (commercial propane preferred). Timers: one to control and measure the flame application time, settable at 1 s in 1 s steps, with an accuracy of 0,2 s or better; three timers reading to 0,2 s or better for the flame spread times — started simultaneously with the application of the igniting flame and stopped automatically when the individual threads are severed. Marker threads: white mercerized cotton with a linear density of 45–50 tex.

PRECAUTIONS (clause 6). Combustion products may be corrosive — apparatus made of materials resistant to the fumes. The volume of air around the test location shall be such that a reduction of oxygen concentration does not affect the test; in an open-fronted cabinet the specimen shall hang at least 300 mm from any wall. Burning produces smoke and toxic gases — between tests the room of adequate size is cleared by an extractor fan or other ventilation. Further clauses (titles from the table of contents only): sampling (7), conditioning and testing atmosphere (8), setting up the apparatus (9), test procedure (10), precision, test report, Annex A (normative) — construction of the burner, Annex B (informative) — experimental techniques.

EDITIONS. ISO 6941:2003 (ISO/TC 38/SC 19 "Burning behaviour of textiles and textile products") — second edition, replaced ISO 6941:1984 after technical revision; it cites ISO 4880:1997 and ISO 6940. ISO 6941:2026 — third edition, prepared by ISO/TC 38 in collaboration with CEN/TC 248 (Vienna Agreement), replaced ISO 6941:2003; changes according to the foreword: corrected Figure 1 b) (angular dimension line and shape of the gas jet tip), revised Figures 3 a) and 3 b) so that the specimen is clearly shown; the revision aims to clarify without structural changes. Scope, definitions and principle are the same in content in both editions. iTeh catalogue card of ISO 6941:2026 (read on 06.11.2026): status "Published", publication 13.05.2026, stage "6060 – International Standard published", ICS 13.220.40 and 59.080.30; next to it EN ISO 6941:2026.

STATUS (as of 06.11.2026). The card of PN-EN ISO 6941:2005 (Polish version) carries the label "Withdrawn and replaced by PN-EN ISO 6941:2026-10 - English version": withdrawal date 27-10-2026, publication 09-12-2005, 20 pages, KT 27 Floor Coverings and Flammability of Textile Products, "Adopts: EN ISO 6941:2003 [IDT], ISO 6941:2003 [IDT]", "Replaces: PN-EN ISO 6941:2004 - English version, PN-EN ISO 6941:2004 - German version", ICS 13.220.40, 59.080.30; in the line "Current in conformity assessment" the card gives "30-11-2026 - See Communication of the President of PKN" (we did not read the communication). "Scope" field of this card (our translation): "A method is specified for measuring flame spread times on vertically oriented textile fabrics and industrial products in the form of single- or multi-component products (coated, quilted, multilayered, sandwich constructions and similar combinations) when subjected to a small defined flame". The card of the successor PN-EN ISO 6941:2026-10 (English version) has no withdrawal label: publication 27-10-2026, 26 pages, KT 27, "Adopts: EN ISO 6941:2026 [IDT], ISO 6941:2026 [IDT]", "Replaces: PN-EN ISO 6941:2005 - Polish version", the same Polish title, a "Scope" field of the same content. Three questions about the withdrawal: when — 27.10.2026; replaced by what — PN-EN ISO 6941:2026-10 (English version; the card lists no Polish version); what changed for the result — according to the foreword of ISO 6941:2026, Figures 1 b), 3 a) and 3 b) were corrected, and the revision aims to clarify without structural changes; scope, definitions and principle are the same in the fragments of both editions we read. We did not compare the full texts of the two editions.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database refreshed from the production server on 02.11.2026 and current PCA documents, read on 06.11.2026). Number 6941 appears in the database copy in 7 records at 6 Polish laboratories: AB 023, AB 029 (two), AB 154, AB 225, AB 304, AB 1280. In the current PCA documents of these 6 laboratories the standard occurs 6 times — once each; the difference comes from the copy: at AB 029 both flammability entries (ignition time and flame spread time) have all seven standards of both rows assigned in the copy, while in PCA PN-EN ISO 6941:2005 stands only with flame spread. No entry is suspended; the entries of AB 023, AB 304 and AB 1280 belong to the flexible scope of accreditation (mark "E"). Notations: "PN-EN ISO 6941:2005" (AB 029, AB 154, AB 225) and "PN-EN ISO 6941" without year (AB 023, AB 304, AB 1280). In the database copy the number also appears in 4 records at 4 Czech laboratories (notation "ČSN EN ISO 6941", also as the basis of an in-house procedure). The "Laboratories" tab ("PN-EN ISO 6941") shows 10 laboratories: these 6 Polish and 4 Czech (tab query on labcoda.pl, 06.11.2026).

WHAT THE LABORATORIES TEST (database copy and PCA documents, complete entries). Time from the application of the igniting flame until the bottom, middle and top marker threads are severed: textile products, curtains and net curtains (AB 225, together with PN-EN 1102:2016-09) and flat textiles (AB 1280 — three times in separate rows). Flammability — flame spread time and occurrence of burning debris, single-flame method: textile products (AB 029, together with PN-EN 1102:2016-09, PN-EN 13772:2012 and PN-EN 1624:2002). Flame spread on vertically oriented specimens: flat textiles (AB 154, together with PN-EN 1624:2002). Combined entries with PN-EN ISO 6940: degree of flammability of flexible products — extent of flame spread and time to ignition: curtains, drapes, theatre curtains, films, tent fabrics, awnings (AB 023); resistance to ignition and vertical flame spread: drapes, curtains, net curtains, large tents, awnings, films and other hanging products (AB 304). No scope indicates procedure A or B.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. First — start of the measurement: the three timers start at the moment the flame is applied, not after it is removed, so the 10 s of application belong to each measured time; counting from the removal of the burner shortens the result. Second — marker threads: white mercerized cotton 45–50 tex, in a loop 1 mm and 5 mm from the front surface of the specimen; a thread of a different type, thickness or at a different distance means different measurement conditions, while the result in seconds looks the same. Third — mode of ignition: the standard has surface and bottom edge ignition, and the scopes do not state it — the test report must state the procedure, because times from the two variants must not be compared with each other. Fourth — mounting: the specimen at least 20 mm from the frame on spacers and at least 300 mm from the cabinet walls, the burner in standby at least 75 mm from the specimen; a specimen without spacers or in too tight a cabinet (the standard requires that a reduction of oxygen concentration does not affect the test) means conditions different from the standard. Fifth — range of validity of the result: the method says nothing about the behaviour of the product with restricted air supply or with a large heat source (introduction of the standard); other tests serve that purpose — at AB 029 and AB 225, for example, PN-EN 13772 is cited alongside, described in the AB 225 scope as a test with a large ignition source. Sixth — citing the edition: three laboratories (AB 029, AB 154, AB 225) cite PN-EN ISO 6941:2005, which PKN withdrew on 27.10.2026 (successor: PN-EN ISO 6941:2026-10, English version), and three in the flexible scope (AB 023, AB 304, AB 1280) — the number without year; the test report must state which edition was used. According to the foreword of the 2026 edition the changes concern figures and do not change the structure — we did not compare the full texts, so we do not claim that the results of both editions are always equivalent.

WHAT WE DO NOT GIVE. The fragments we read end: ISO 6941:2003 — at 6.3, ISO 6941:2026 — at clause 4. We do not give the number, cutting dimensions and direction of specimens, conditioning conditions, burner position and flame height, the position of the marker threads along the height of the specimen, the test procedure, precision, test report content or burner construction (clauses 7–12, Annexes A and B). We did not check the status of the standards cited alongside in the scopes (PN-EN 1102, PN-EN 1624, PN-EN 13772); we did not check references to ISO 6941 in legislation.

Method principle

A textile specimen hung vertically on pins is ignited by a defined burner flame applied for 10 s to the surface or the bottom edge; three timers started with the application of the flame stop automatically when the flame front severs successive cotton marker threads stretched just next to the specimen surface at three distances from the flame — the results are the flame spread times in seconds (ISO 6941:2003, clauses 4–5).

Applications

• Textile fabrics and industrial products, single- and multi-component: coated, quilted, multilayered, sandwich (ISO 6941:2003, clause 1)
• Influence of seams and trimmings on flame spread (introduction of the standard)
• Paired with ISO 6940 (ease of ignition) — according to the introduction, two closely related methods of testing the flammability of textile fabrics
• In accreditation scopes: 6 Polish laboratories — textile products, flat textiles, curtains, net curtains, drapes, theatre curtains, large tents, awnings, films and other hanging products

Key parameters

Standard

Standard number

PN-EN ISO 6941:2026-10 (English version; adopts EN ISO 6941:2026 and ISO 6941:2026 [IDT]; replaced PN-EN ISO 6941:2005 — Polish version, withdrawn on 27.10.2026)

Title (PL)

Wyroby włókiennicze — Zachowanie się podczas palenia — Pomiar właściwości rozprzestrzeniania się płomienia na pionowo umieszczonych próbkach

Title (EN)

Textile fabrics — Burning behaviour — Measurement of flame spread properties of vertically oriented specimens

Step-by-step procedure

1. Specimens

   Specimens 560 × 170 mm with pin holes marked with the template; number, direction and conditioning according to clauses 7–8 (not read).

2. Mounting

   Specimen vertical on 12 pins, at least 20 mm from the frame; three marker thread loops 1 mm and 5 mm from the front surface; test location at least 300 mm from the cabinet walls (5.1, 5.3, 6.2).

3. Flame

   Burner from the standby position (≥ 75 mm) to the operating position — to the surface (procedure A) or the bottom edge (procedure B); flame for 10 s (clause 4, 5.2; flame adjustment — clause 9, not read).

   ⏱ Time: 10 s

4. Measurement

   Three timers start with the application of the flame and stop when successive marker threads are severed; reading to 0,2 s or better (5.6.2).

5. Result

   Flame spread times to the three threads, stating the ignition procedure (test report content — not read). PN-EN ISO 6941:2005 — withdrawn on 27.10.2026, successor PN-EN ISO 6941:2026-10 (English version; PKN cards, 06.11.2026).

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• TECHNICAL NOTE: the times are counted from the application of the flame, not from its removal
• TECHNICAL NOTE: the result does not apply to conditions with restricted air supply or large heat sources (introduction of the standard)
• Smoke and toxic gases from combustion — ventilation of the room between tests; combustion products may be corrosive (6.1, 6.3)
• Open flame and flammable gas (propane, butane) — protection against burns and gas leaks

Frequently asked questions