AFAP-05 heat release rate testing for materials

What it is

AFAP-5 (Allied Fire Assessment Publication 5, Edition 3) is the NATO document that defines how to measure a material's heat release rate using a cone calorimeter. It is an implementation of ISO 5660-1, and it says so directly: the procedure "is an implementation of ISO 5660-1," supplemented with "detailed requirements for specimen preparation for particular types of material, additional details for test and calibration procedures... and requirements for data presentation." It cannot be used on its own - AFAP-5 states that "only the information that is additional to ISO 5660-1 is included in this document" and that it "must be read in conjunction with a copy of ISO 5660-1."

AFAP-5 is the fifth in a five-part series. AFAP-1 sets the policy for pre-selecting materials by their fire characteristics (and the irradiance level and Ship Type classifications the other four parts use); AFAP-2 covers smoke generation, AFAP-3 toxicity of fire effluents, AFAP-4 surface spread of flame, and AFAP-5 heat release rate. NATO nations' agreement to use the series is recorded in STANAG 4602. Edition 3 was promulgated in July 2010, is effective on receipt, and supersedes Edition 2.

Who runs the test, and why

The document addresses the test laboratory that operates the cone calorimeter, and the supplier and manufacturer whose material is submitted for evaluation - the test report has to name both, "the name and address of the supplier and where different, of the manufacturer (original source) of the material tested." It also defines a Technical Authority: "the relevant national authority, responsible for providing regulations and guidance on fire reaction of materials associated with procurement and in service support." The Technical Authority decides certain test parameters (which face of a laminated or asymmetrical product gets tested, for example) and is the point of contact for any question about how the publication applies to a tender or contract.

When it binds

AFAP-5 has force because nations have agreed to use it: "the agreement of interested nations to use this publication is recorded in STANAG 4602." That agreement reaches a supplier or laboratory through a tender or contract, not automatically - the preface says enquiries "in relation to an invitation to tender or a contract in which it is incorporated are to be addressed to the Technical Authority." Read plainly, that means AFAP-5 is something a laboratory or supplier is asked to test against because a specific contract requires it, at the point a material needs qualifying, rather than a standard to design a process around in advance of any contract.

Materials, and specimen preparation

The heat release rate test applies to whatever material a Technical Authority submits for evaluation. AFAP-5's annexes set out specific preparation methods for several material types:

• Paint and coating systems, applied to 100 x 100 mm mild steel panels per the manufacturer's

instructions, cured, then conditioned for 7 days at (23 +/- 2) degC and (50 +/- 10)% relative humidity before testing within a further 7 days.

• Tubes and pipes, cut into flat strips if the material is flexible, or curved strips sized to

fill a 100 mm specimen width if it is rigid.

• Upholstered furniture and mattresses, tested as an assembled composite of every covering,

interliner and padding layer in the order and thickness they occur in the finished item (reduced proportionally above a 50 mm total). Component squares are cut and weighed to a 95-105% mass tolerance before assembly, and covers that have been chemically treated to reduce ignitability go through the water-soak and drying procedure from Annex E of BS 5852 first. That water-soak step is specific to AFAP-5: "water soak or washing procedures are only required for assessment of heat release rate in accordance with AFAP-5 and shall not be undertaken for tests according to AFAP-2 or AFAP-3."

A table in Annex 2 sets the required specimen form for each named material type, including interior deck coverings, thermal insulation and decorative linings.

Running the test

Three specimens are tested at the irradiance level AFAP-1 requires, 25 or 50 kW/m2. Where materials have faces that differ, "the Technical Authority shall determine which of the faces are required to be tested," and a result is only valid for the face actually tested. Materials that can decompose explosively when heated need a specimen holder secured strongly enough to contain the reaction. Data is scanned every 2 seconds or less, and the test runs until whichever comes first: 22 minutes after sustained flaming, 20 minutes with no ignition, the oxygen reading returning to its pre-test baseline for 10 minutes, or the specimen reaching zero mass, subject to a 5-minute minimum.

Beyond the standard ISO 5660-1 heat release rate calculation, AFAP-5 adds MARHE (the Maximum Average Rate of Heat Emission) and, for generic materials and Ship Type (H) upholstery work specifically, the 30-second sliding averages HRR30max and SPR30max. Smoke production measurement against ISO 5660-2 is optional generally, but becomes mandatory when evaluating furniture or components as "fire-restricting materials" for Ship Type (H).

What the test report has to contain

Clause 11 sets out a defined content list: laboratory and supplier/manufacturer identity, test dates, a detailed material description (composition, form, dimensions, coatings, NATO stock numbers, prior test history), a full ISO 5660-1 report, the individual and 3-specimen average MARHE or HRR30max/SPR30max figures, additional details such as which gas-sampling method was used and the heat flux meter's calibration traceability, and a mandated disclaimer that "these results relate only to the behaviour of the specimens of the material under the particular conditions of test."

How you are evaluated

AFAP-5 describes no certification scheme, and no accredited body or notified body appears anywhere in it. It is a laboratory test method: a test house runs it and produces a report, and the Technical Authority - the national authority for fire reaction, procurement and in-service support

• sets certain parameters and uses the resulting figures for its own material decisions, optionally

feeding the Materials Fire Characteristics Data Sheets that STANAG 4602's database holds. That is a national authority directing and using a technical result, not a certification of a material or an organisation.

Standards it references

Clause 2 normatively references six documents. STANAG 4602 records the nations' agreement to use the AFAP series and is how AFAP-5 acquires contractual force. The remaining five are civil standards outside this catalogue: ISO 5660-1 is the base cone calorimeter method AFAP-5 supplements; ISO 5660-2 supplies the smoke-production measurement AFAP-5 references; ISO 291 sets the conditioning atmosphere used for test specimens; ISO 1514 is pointed to for surface preparation technique examples; and BS 5852 supplies the water-soak procedure used on treated upholstery covers. AFAP-5 also depends on AFAP-1 for the irradiance level and Ship Type classifications several of its clauses refer back to.

Standards it references

• AFAP-01Binds
• AFAP-02Background
• AFAP-03Background
• AFAP-04Background