Non-Combustibility Test (ISO 1182): Criteria and Apparatus

The Short Answer

The non-combustibility test is the 750 °C tube-furnace method defined by ISO 1182. A cylindrical specimen is lowered into a pre-stabilised furnace and observed for a defined exposure period; the result is expressed as furnace temperature rise, mass loss and duration of sustained flaming. If you need one bench that can serve ISO 1182:2020, ASTM E136, ASTM E2652, GB/T 5464-2026 and IMO FTP Code Part 1, specify a cone-stabiliser furnace with two furnace thermocouples — the single-thermocouple layout predates the 2020 edition and cannot claim it. The JBR20 non-combustibility apparatus is built to that configuration.

BRT JBR20 Non-Combustibility Testing Apparatus

What the Non-Combustibility Test Actually Measures

The test does not tell you how a material behaves in a real fire. It tells you whether a small, standardised specimen adds measurable heat and flame to a furnace already held at 750 °C 1. That distinction is the whole point: the method is a screening tool for materials that should not contribute to fire development at all.

Three quantities come out of a run, and each attacks a different part of that question:

• Furnace temperature rise (ΔT) — how much hotter the furnace became because the specimen was inside it.
• Mass loss (Δm) — how much of the specimen decomposed or burned away.
• Sustained flaming (t_f) — how long the specimen kept burning under its own steam.

A result that shows a small ΔT, little mass loss and no sustained flaming is read as “does not significantly contribute to fire” — the working definition of non-combustible in most building codes 5. The method is also deliberately narrow: ASTM states that no intrinsic property is measured, that self-heating is not assessed, and that results apply only to the specific apparatus and condition used 7. Treat it as a classification instrument, not a fire-safety verdict.

One Furnace, Four Rulebooks

The same physical setup sits underneath ISO 1182, ASTM E136, ASTM E2652, GB/T 5464 and IMO FTP Code Part 1. What changes between them is who wrote the rule, which edition is in force, and — in exactly one place — how many thermocouples the furnace must carry.

Which Rulebook Applies to Which Market

A laboratory selling into several markets does not need several machines. It needs one furnace whose geometry satisfies the strictest of the applicable documents, and a procedure that switches criteria rather than hardware. ISO 1182:2020 is the natural anchor: EN ISO 1182:2020 is the CEN adoption of the same text, GB/T 5464-2026 is a modified adoption of it 8, and IMO FTP Code Part 1 uses a furnace of the same family [11].

The One Real Hardware Difference: One Furnace Thermocouple or Two

ASTM is unusually candid about the split. ASTM E2652-22 is described as technically equivalent to ISO 1182:2010, and its Note 1 states plainly that ISO 1182:2020 added a second furnace thermocouple while the ASTM method continues to use one [7]. ASTM E136-24c carries the same asymmetry, and it accepts two furnace designs: Option A, the classic ceramic tube with concentric refractory tubes, and Option B, the cone-shaped airflow stabiliser design — which is the same design as E2652 6.

That gives a buyer a clean decision rule. If your scope includes ISO 1182:2020 or GB/T 5464-2026, the furnace must have two wall thermocouples. A single-thermocouple furnace can still run the older ISO 1182:2010 procedure and the ASTM methods, but it cannot produce a current-edition ISO or Chinese result — and that gap is not fixable with a software update.

The Pass Criteria, By Market

The apparatus is shared; the pass/fail numbers are not 4. Averaged across the required number of specimens, the thresholds differ enough that a material classified one way in Europe can fail in a marine application.

Two details in that table are routinely missed. The IMO route constrains the surface thermocouple as well as the furnace thermocouple — so a furnace bought only for ISO 1182 needs specimen-surface and centre channels before it can support marine work. And the A1 flaming criterion is zero, not “a short flare”; A2 is the class that tolerates up to 20 seconds.

Specimens and Conditioning: Where Most Retests Come From

Non-Combustibility Test Specimens: Geometry and Number

The specimen is a cylinder, nominally Ø45 mm by 50 mm high, and the standard requires a defined number of parallel specimens so that the reported figure is an average rather than a single lucky run [1]. Three practical consequences follow. A material supplied as a thin sheet has to be built up into the required cylinder rather than tested flat. Granular and loose-fibre products go into a container rather than being pressed into shape. And because the result is an average, one anomalous specimen drags the whole declaration — which is usually why a borderline product reports differently between two laboratories.

Substantial Components and the Coating Trap

The test applies to homogeneous products and to the substantial components of non-homogeneous products [1]2. In plain terms: you test the part of a composite that carries the fire performance, not the decorative face. This is where quotations go wrong most often — a mineral core with a thin applied film is a core test, not a panel test, and the wrong sample produces a number no certification body will accept, at full sample-preparation cost.

Conditioning compounds the risk. The regime sits in a separate document — EN 13238 in Europe, with the equivalent Chinese procedure referenced alongside the test method [8]. A laboratory that conditions to a different schedule than the one its accreditation covers can pass the furnace run and still lose the certificate.

What the Apparatus Must Deliver

The furnace is a simple object with unforgiving tolerances, and the difference between a compliant bench and a lookalike is almost entirely in the instrumentation. That is the distinction the non-combustibility apparatus specification in this section is designed to test.

Furnace Tube, Thermocouples and the Airflow Stabiliser

The refractory tube is specified by dimension, not description: a defined height, bore and wall thickness in an alumina-based refractory, with an open-ended cone-shaped airflow stabiliser above it to keep the convection regime repeatable [1]. Thermocouples are Class 1 Type K, and ISO 1182:2020 requires two in the furnace wall rather than one [7]. The standard also carries a normative annex for the additional measurement channels — specimen surface and specimen centre — so those probes are part of the specification, not an optional extra [1]. For IMO FTP Code Part 1 work the surface channel is mandatory in practice, because the pass criteria reference it directly [3].

Stabilisation, Drift and Voltage Compensation

Before a specimen goes near the furnace, the furnace has to be at 750 °C and genuinely steady. The standard’s acceptance logic hinges on how little the furnace drifts over a defined period [1], and that is what furnace calibration verifies — which is why mains quality matters more than it looks. A heating circuit that follows the building’s supply voltage will wander in temperature, and a run performed during a voltage sag has to be repeated. Power compensation — holding heating power stable and empty-furnace temperature variance inside a small band while the supply moves — converts a furnace from “reaches 750 °C” into “stays at 750 °C”. A staged soft-start curve is its companion: it protects the heating elements from thermal shock, the usual cause of a furnace drifting out of tolerance eighteen months after installation.

Running the Test: From Stabilisation to Reported Result

The data volume is the part buyers underestimate. One run produces three continuously logged temperature curves, a flaming record and a mass measurement — which is why automatic flame-duration logging matters. Manual stopwatch timing is a documented error source that hides in the final report.

Non-Combustibility Is Not Fire Resistance

This is the most expensive confusion in the field. Non-combustibility asks what a material contributes to a fire. Fire resistance asks how long an assembly — a wall, a door, a duct penetration — holds back a fire already burning next to it. Different standards, different specimens, different apparatus, different reports.

A specification that asks for a “non-combustible fire-rated wall” without separating the two is asking for two certificates, and only one of them comes off a 750 °C tube furnace.

Where the Test Sits in the Euroclass System

The non-combustibility test is one input into a classification decision 12, never the decision itself. That is the single most useful thing to understand before quoting a European certification programme.

A supplier with a clean ISO 1182 report has satisfied one of two conditions for A1, and possibly only half of A2: the furnace is necessary, never sufficient. For the routing logic across all four EN 13501-1 tests, see our guide to reaction to fire testing and the Euroclass and SBI testing walkthrough. The single burning item half of the pair is covered by the SBI test apparatus, the heat-of-combustion half by the gross heat of combustion tester — confirm the model against your target class, since the two halves of A1 are often procured a year apart.

What Changed in ISO 1182:2020 and GB/T 5464-2026

Four changes in the current editions change what you should buy.

Taken together, the direction is consistent: the newer editions want more measurement channels and more stable furnace conditions, which is a hardware requirement rather than a documentation exercise.

Specifying a Non-Combustibility Apparatus

Ten questions separate a specification from a wish list. Each maps to a clause in the standard, and each is cheap to ask before purchase and expensive to discover after.

If your scope is wider than the furnace test, the same category holds the rest of the chain: the fire and flame testing equipment range covers the single flame source route through the building material combustibility apparatus and the heat-release route through the cone calorimeter, covered method-side in our ISO 5660 cone calorimeter guide. For how these standards travel between regions, see the global building material fire testing standards overview.

Frequently Asked Questions

Is the non-combustibility test the same as ASTM E136?

Not identical, but closely related. ASTM E136-24c and ISO 1182 both expose a specimen to a 750 °C furnace and both report a temperature rise, a mass loss and a flaming observation. The differences are the pass criteria, set per market, and the thermocouple count: E136 uses one furnace thermocouple while ISO 1182:2020 requires two [6][7]. A cone-stabiliser furnace built to the current ISO configuration serves both routes.

What is the difference between ISO 1182 and EN ISO 1182?

They are the same technical text issued by two bodies. ISO 1182:2020 is the international standard; EN ISO 1182:2020 is the European adoption, published by CEN and used as the basis for CE marking under the Construction Products Regulation [2][12]. A report citing EN ISO 1182:2020 is a report citing ISO 1182:2020, and no laboratory needs separate apparatus for the two.

How long does a non-combustibility test take?

Budget more than the furnace run. Specimen conditioning comes first and can take a day or longer, then the furnace has to be stabilised at 750 °C before the first specimen goes in, then each specimen is exposed and finally cooled before it can be weighed. The exposure itself is short compared with the stabilisation and conditioning that bracket it, and a full parallel set multiplies the exposure step.

How many specimens do I need?

The standard requires a set of parallel specimens and averages the result, rather than accepting a single run [1]. The practical consequence is that you should cost a test programme, not a test. Ask the laboratory how many specimens it prepares per material and how it treats a specimen that fails to stabilise, because the quotation is usually written per material with the specimen count buried in the assumptions.

Can I test coated or laminated products?

Not as a finished panel. ASTM E2652 explicitly excludes laminated and coated materials from its scope [7], and ISO 1182 addresses homogeneous products and the substantial components of non-homogeneous ones [1][2]. In practice you test the layer that carries the fire performance — typically the core — and you confirm with your certification body whether the remaining component is dealt with as a separate test item.

What is a passing result for ISO 1182?

It depends on the class you are declaring, not on the method alone. For European Class A1, the averaged furnace temperature rise must stay at or below 30 °C, the averaged mass loss at or below 50 %, and there must be no sustained flaming [3]. Class A2 relaxes the temperature rise to 50 °C and the flaming limit to 20 seconds [3]. Marine work under IMO FTP Code Part 1 also constrains the specimen surface thermocouple [3].

Why does my furnace fail calibration at 750 °C?

Usually because the heating circuit follows the building supply rather than holding power steady, or because the heating elements have aged and the soft-start profile no longer compensates. Furnace calibration checks the drift at temperature, not the ability to reach it, so a furnace reporting 750 °C on the display can still fail [1]. Power compensation and a staged ramp address both causes, and both should be confirmed as fitted features rather than software options.

Does a non-combustibility test replace a fire resistance test?

No, and the two are routinely confused in specifications. Non-combustibility describes what a material contributes to a fire; fire resistance describes how long an assembly holds a fire back. They use different apparatus and produce different certificates. A specification that asks for both should expect two separate reports, and the non-combustibility half comes off a 750 °C tube furnace.

Conclusion: The Decision Order

Work in this order and the procurement question answers itself:

1. List the markets you must certify for. Europe, North America, China and marine each add a rulebook.
2. Check which edition is in force in each. ISO 1182:2020 and GB/T 5464-2026 both require two furnace thermocouples.
3. Confirm the class you are declaring. A1 needs the non-combustibility test and the heat-of-combustion test; A2 needs one of them plus a main fire test.
4. Specify the furnace, not the price. Thermocouple count, tube geometry, drift and power compensation decide whether the bench is compliant in three years.
5. Confirm the probe channels and the calibration evidence before ordering. IMO Part 1 work needs the surface channel, and accreditation-ready documentation is far cheaper up front than as a retrofit.

Shenyang Baoruitong Automation Equipment Co., Ltd. (BRT) manufactures the JBR20 non-combustibility apparatus and the wider fire and flame testing equipment range, and supplies 200+ testing equipment models to laboratories in 50+ countries under an ISO 9001/13485 certified quality system. To confirm a configuration against your target class and market, send the standard list you must certify against — the specification answer usually comes down to two questions about thermocouples and probe channels.