Combustion smoke toxicity tester

The GB/T 19666 Toxicity Index Tester is a specialized instrument designed for evaluating the toxicity of combustion gases generated from flame-retardant and fire-resistant wires, cables, and optical cables. Based on controlled thermal decomposition or combustion in a tube furnace, the system introduces a defined flow of smoke into standard absorption solutions or gas sampling bags for subsequent quantitative analysis. The tester is widely applied in smoke toxicity assessments required by railway, cable, and fire safety standards, providing reliable data to support material safety evaluation under fire conditions.

Application

The ASTM E1678 Combustion smoke toxicity tester is used for smoke toxicity testing in accordance with multiple international and regional standards. Typical application scenarios include:

Flame-retardant and fire-resistant power cables

Railway rolling stock cables and signal cables

Optical fiber cables and communication cables

Polymer insulation and sheath materials

Halogen-containing and halogen-free cable compounds

The instrument supports both absorption-liquid analysis and gas bag collection methods, allowing flexible downstream analysis depending on the test standard and laboratory requirements.

Standards

The system complies with the following standards and test methods:

(1) GB/T 19666 – General Rules for Flame-Retardant and Fire-Resistant Wires, Cables or Optical Cables

(2) EN 50305 – Railway Applications – Test Methods for Fire Behaviour of Electric Cables

(3) BS 6853 Annex B – Code of Practice for Fire Precautions in the Design and Construction of Passenger Carrying Trains

(4) ISO 19700 – Controlled Equivalence Ratio Method for the Determination of Toxic Product Yields in Fire Effluents (Steady-State Tube Furnace Method)

(5) ASTM E1678

(6) NFPA 269

Parameters

Features

Sealed chamber design with the smoke generation system installed internally, providing stable operation and effective protection of core components

Large observation window allowing clear visual monitoring of test status and specimen movement

Integrated industrial design with panel-mounted structure, offering intuitive operation and ergonomic user interface

Tube furnace protected by perforated outer housing to enhance heat dissipation and ensure uniform temperature rise to the target value

High-temperature K-type thermocouple for accurate measurement of specimen zone temperature

Ceramic combustion boat driven by strong magnetic coupling and transmission mechanism for stable and repeatable specimen delivery into the furnace core

Precision lead-screw transmission system enabling accurate positioning and reliable sealing of the quartz tube, reducing the risk of damage due to manual operation

Dual filtration columns filled with activated carbon and color-changing silica gel for effective carrier gas purification and drying

Branded computer with dedicated control software for automatic test process control

Software-based temperature regulation and stabilization with real-time curve recording, automatic data display, storage, and report generation

Accessories

(1) Heat-resistant quartz tube

(2) Ceramic combustion boat

(3) PTFE-coated gas sampling bag (80 L)

(4) Activated carbon filter column

(5) Color-changing silica gel filter column

(6) K-type thermocouple

(7) Dedicated control software and industrial computer

Test Procedures

1. Pre-Test Preparation

Ensure the tester is installed in a well-ventilated laboratory environment. Verify that the tube furnace, quartz tube, and filtration system are clean and properly assembled. Check that the absorption solution (0.1 N NaOH) and titration reagents are prepared according to specified concentrations. Confirm normal operation of the temperature control system, gas analysis instruments, and data acquisition software.

2. Specimen Loading

Place the prepared test specimen into the ceramic combustion boat. Using the magnetic drive and transmission mechanism, steadily convey the boat into the center of the tube furnace. The lead-screw positioning system ensures accurate alignment and reliable sealing at the quartz tube interface, minimizing gas leakage during the test.

3. Heating and Smoke Generation

Set the target temperature according to the selected standard. The furnace temperature is automatically controlled by the software, with uniform heating achieved through regulated power output. As the specimen undergoes thermal decomposition or combustion, the generated smoke is carried by a controlled gas flow toward the sampling and absorption system.

4. Gas Collection and Analysis

The combustion gases are either introduced into the NaOH absorption solution via bubbling or collected in PTFE-coated gas sampling bags for subsequent analysis. Online infrared gas analyzers continuously measure CO and CO₂ concentrations, while SO₂ and NOₓ are determined using dedicated measurement channels or chemical analysis methods. All test data are automatically recorded and stored by the control software.

Maintenance Information

Regularly inspect the quartz tube, ceramic combustion boat, and furnace interior for residue buildup and clean them as required. Check the condition of the activated carbon and silica gel in the filter columns and replace them when saturation or discoloration is observed. Verify calibration of gas analyzers and temperature sensors according to laboratory quality procedures. Ensure the lead-screw transmission and magnetic drive mechanisms operate smoothly to maintain positioning accuracy.

Conclusion

The GB/T 19666 Toxicity Index Tester provides a comprehensive and standardized solution for evaluating the toxicity of fire effluents from cables and related materials. By integrating precise temperature control, stable smoke generation, flexible gas collection methods, and automated data processing, the system meets the requirements of GB/T, EN, BS, and ISO standards, supporting reliable fire safety assessment in railway and cable industries.

FAQ

What types of materials can be tested using the GB/T 19666 Toxicity Index Tester?

The tester is primarily designed for flame-retardant and fire-resistant wires, cables, and optical cables. It is also suitable for evaluating polymer insulation materials, sheath compounds, and other cable-related materials that may generate toxic gases during combustion or thermal decomposition. The test configuration supports both halogen-containing and halogen-free materials, in accordance with GB/T 19666 and related international standards.

How are combustion gases collected during the test?

Combustion gases generated in the tube furnace are transported by a controlled carrier gas flow. Depending on the test requirement, the gases are either bubbled through a standard 0.1 N NaOH absorption solution or collected in an 80 L PTFE-coated gas sampling bag. This dual approach allows compatibility with different analytical methods specified in EN 50305. BS 6853 Annex B, and ISO 19700. ensuring accurate downstream toxicity analysis.

Why is precise temperature control important in toxicity index testing?

Accurate and stable temperature control is critical because the type and concentration of toxic gases produced during combustion are strongly dependent on thermal conditions. The software-controlled tube furnace ensures uniform heating and precise temperature regulation up to 1100 °C, while real-time temperature recording allows verification of test repeatability and compliance with standard requirements.

Which gases are measured by the system?

The system measures key toxic combustion gases including SO₂, NOₓ, CO, and CO₂. Online infrared gas analyzers provide continuous CO and CO₂ measurements, while SO₂ and NOₓ are determined through dedicated detection channels or chemical analysis methods based on collected samples.