Alcohol Burner Test for Polymer Products Used in Underground Mines: Standards, Methods, and Complian

The alcohol burner test is a fundamental flame-retardancy evaluation for polymer products deployed in underground mine environments, where methane gas and combustible dust demand materials that ignite reluctantly and self-extinguish rapidly. Performed in accordance with the Chinese coal industry standard MT 113 and related product standards, the test exposes inclined specimens to a calibrated alcohol blast burner flame of approximately 960 °C and measures after-flame time, charred length, and flaming debris behavior. This article explains the test principle, specimen requirements, operating procedure, acceptance criteria, and the role of the test in mine safety certification and quality control.

Technical Overview

Underground coal mines and other underground workings contain firedamp (methane) and combustible coal dust, so any polymeric material taken below ground—conveyor belting, ventilation ducting, hoses, cable sheathing, safety netting, and lining boards—must not act as a source of flame propagation. Because polymers such as PVC, rubber, polyurethane, polyethylene, and glass-reinforced plastics are inherently combustible, they must be compounded with flame-retardant systems and verified through standardized flammability testing before they are approved for underground service.

The alcohol burner test is the principal laboratory-scale method used within the Chinese mining regulatory framework to verify this self-extinguishing behavior. In this test, a rectangular specimen is mounted at an inclined angle and exposed to the flame of a calibrated alcohol blast burner for a fixed duration. After the burner is removed, the laboratory records how long the specimen continues to burn, how far the material is damaged, and whether burning molten debris is released. A material that continues flaming for more than a few seconds, or that drips flaming particles, is rejected.

The umbrella method standard is MT 113, General test methods and judgment rules for flame-retardant and antistatic properties of polymer products used in underground coal mines, which specifies the alcohol burner test and is referenced by numerous product-specific standards for conveyor belts, ventilation ducting, and other underground polymer goods. Comparable international flammability assessments for mining conveyor belts include the propane-burner-based EN ISO 340 and related EN and AS test series, although the ignition source, flame temperature, and pass criteria differ from the alcohol burner regime.

• Governing method standard: MT 113 (coal industry standard for flame-retardant and antistatic polymer products)
• Typical companion product standards: those covering solid-woven flame-retardant conveyor belting, mine ventilation ducting, plastic netting, and similar underground polymer goods
• Ignition source: alcohol blast burner fueled by ethanol, with a flame calibrated to approximately 960 °C
• Regulatory function: supporting mine safety product certification and factory quality control for underground use

Testing Samples

Conveyor Belting and Belt Accessories

Solid-woven PVC, PVG, and rubber-covered flame-retardant conveyor belts are among the most safety-critical products tested. Belt cover compounds and the impregnated carcass are cut into specimens oriented both along and across the belt so that flame behavior is checked in both directions. Belt cleaning blades, skirt rubber, and impact bars made of polymer are also commonly evaluated.

Ventilation Ducting

Flexible positive-pressure and negative-pressure air ducts, typically coated fabric constructions of PVC or rubber, are tested because they run continuously through airflow paths where any sustained burning would rapidly spread smoke and fire along roadways. Both the coating layer and the full composite fabric structure may be sampled.

Pipes, Hoses, and Cable Sheathing

Water drainage pipes, compressed-air hoses, emulsion hoses, and the polymeric sheaths and jackets of mining power cables are subjected to alcohol burner testing to confirm that an accidental flame contact will not lead to sustained combustion or flaming drips onto other equipment.

Netting, Liners, and Miscellaneous Polymer Components

Roof-support plastic netting, glass-reinforced plastic lining sheets, seals, gaskets, airlock curtains, dust-suppression components, and polymer repair materials used underground are all within the scope of the test program. In general, any polymer product intended for underground use in a gassy mine must demonstrate flame-retardant compliance.

Testing Items

The alcohol burner test generates a defined set of flammability measurements, which are then compared against the acceptance limits of the applicable product standard. The core observations are:

• After-flame time: the duration, in seconds, for which each specimen continues to burn with a visible flame after the burner is withdrawn
• After-glow time: the duration of flameless glowing combustion remaining after flaming stops
• Charred or damaged length: the extent of the specimen affected by heat and flame, measured after cooling and cleaning
• Flame propagation behavior: whether burning extends beyond the directly impinged zone toward the clamped upper end of the specimen
• Flaming drips and debris: whether molten or burning material detaches and falls during or after the exposure
• Companion antistatic verification: surface resistance measurement performed under the same MT 113 framework, since underground polymer products must simultaneously satisfy flame-retardant and static-dissipation requirements

Testing Methods

Specimen Preparation and Conditioning

Six specimens are normally cut from the submitted product: three oriented in the machine (longitudinal) direction and three in the transverse direction. Typical specimen dimensions are 360 mm in length and 50 mm in width, taken at the full thickness of the product as delivered. Edges are cut cleanly without fraying or melting, specimens are marked for identification, and they are conditioned in a controlled laboratory atmosphere before testing so that temperature and humidity do not distort the burning behavior.

Apparatus and Flame Calibration

The test uses an alcohol blast burner supplied with ethanol of the specified purity. Unlike a simple spirit lamp, the blast burner premixes air with alcohol vapor to produce a hot, forceful flame whose temperature is calibrated to approximately 960 °C, verified with suitable instrumentation before test campaigns. The burner and specimen holder are installed in a draft-protected enclosure or fume hood so that ambient air movement does not influence the flame, and the burner is positioned so that the lower edge of the inclined specimen sits at the specified distance above the nozzle, typically 50 mm.

Exposure Procedure

Each specimen is mounted at an inclination of 45 degrees to the horizontal. The calibrated burner flame is applied to the specimen for the exposure time defined by the standard, commonly 30 seconds. The operator observes whether the specimen ignites, notes any flaming drips, and at the end of the exposure period withdraws the burner while immediately starting the timer. Timing of after-flame and after-glow behavior continues until all combustion activity ceases. The sequence is repeated for all six specimens, one at a time, under identical conditions.

Observations and Measurements

After each specimen has cooled, the charred or heat-affected length is measured and the specimen is photographed and retained as evidence. The laboratory records the after-flame time for each individual specimen, the aggregate behavior of the longitudinal and transverse sets, and any flaming debris events. These raw results are tabulated and compared with the pass limits of the governing product standard.

Acceptance Criteria and Retesting

Under MT 113 and the product standards that reference it, acceptance is built around rapid self-extinguishment: each specimen must stop flaming within a short, strictly specified limit—commonly no more than 3 seconds per specimen—after removal of the burner flame, with no sustained propagation along the specimen and no release of flaming drips. Limits on the extent of the damaged or charred region are set by the individual product standards. Many standards also include retest provisions, for example permitting or requiring a repeat test on double the number of specimens when a single result is borderline, with the final conformity judgment made in accordance with the specific rule for that product family. Because exact numeric limits vary between products, the applicable product standard must always be confirmed before testing.

Applications

Alcohol burner test data underpins several distinct activities across the life cycle of underground polymer products:

• Mine safety certification: providing the flammability evidence required for national mine safety product approval schemes before polymer goods may be taken underground in gassy coal mines
• Flame-retardant formulation development: comparing halogen–antimony, phosphorus-based, and mineral-filled (ATH/MDH) systems during compound optimization and cost engineering
• Factory quality control and batch release: verifying that production lots maintain the certified flame-retardant performance, including checks after raw-material or supplier changes
• Type testing for tenders and procurement: supplying third-party laboratory reports that satisfy mine operators and equipment vendors during prequalification
• Failure and incident analysis: re-testing retained samples after field fire events or aging studies to determine whether material degradation contributed to the outcome

FAQ

What does the alcohol burner test demonstrate?

It demonstrates that a polymer product, when contacted by a severe open flame, ignites only briefly and self-extinguishes within seconds of the flame being removed, without propagating fire or dropping burning debris. This behavior is essential wherever methane and coal dust make any sustained flame source hazardous.

Which standard governs the test?

The general method and judgment rules are defined in the coal industry standard MT 113, which is invoked by product-specific standards for conveyor belting, ventilation ducting, netting, and other underground polymer products. International customers may additionally require propane-burner tests such as EN ISO 340, which use a different ignition source and criteria.

How many specimens are tested, and how are they oriented?

Normally six specimens are tested—three cut in the longitudinal direction and three in the transverse direction of the product—each at full product thickness and typical dimensions of 360 mm by 50 mm, so that direction-dependent burning behavior is captured.

What results cause a failure?

Typical failure modes include any specimen continuing to flame longer than the per-specimen limit after burner removal (commonly more than 3 seconds), burning that spreads along the specimen, excessive charred length, and the release of flaming molten drips. A single non-conforming specimen generally prevents acceptance unless the applicable standard's retest rules allow otherwise.

Where should the test be performed?

Testing should be carried out by accredited third-party laboratories or by in-house laboratories whose equipment calibration and procedures conform to the governing standard, particularly when the results will be used for mine safety certification or contractual acceptance.

Is the alcohol burner test sufficient on its own for underground approval?

No. It is one component of a broader conformity package that typically also includes surface-resistance (antistatic) testing under the same MT 113 framework, plus product-specific requirements such as drum friction, abrasion, tensile, and aging tests, depending on the product category and the certification scheme involved.