What is the elevated temperature oxygen index?

The High-Temperature Oxygen Index (TOI) measuring instrument determines oxygen index at up to 125°C, offering better flammability assessment than traditional methods. As gas temperature increases, the oxygen index decreases. It follows ISO 4589 Part 3 or NES 715 standards, achieving high temps via preheated gas and furnace wall settings. A built-in pump conserves gas between tests, with nitrogen and oxygen bottles connected only during testing.

Application

Evaluating material combustion performance in R&D.

Quality control for product acceptance.

High-temperature safety assessment in industries like aerospace, automotive, and construction.

Standards

ISO 4589-3: Plastics – Oxygen index method (high-temperature test).

GB/T 2406.2 / ISO 4589-2: Plastic oxygen index test (normal/high-temperature).

ASTM D2863: Plastic oxygen index standard.

GB/T 5454-1997: Textile oxygen index method.

NES 714/715: UK oxygen index test standards.

Product Advantages

High-Temperature Precision: Tests up to 200°C with rapid response (10s heating).

Accurate Oxygen Control: ±0.5% concentration accuracy (0–100% range).

User-Friendly Design: Full-color touchscreen with Chinese/English interfaces.

Versatile Testing: Suitable for diverse materials (plastics, rubber, textiles).

Safety Compliance: Meets global standards for reliable data.

Key Components

Heat-Resistant Cylinder: Borosilicate glass (inner dia. >75mm, height >550mm).

Stainless Steel Beads: Enhances gas flow uniformity (4mm dia., 80–100mm height).

Pilot Burner: 2mm inner dia., 400mm length for precise ignition.

Gas Control: Automated oxygen/nitrogen mixing with flow rate 12.1L/min.

Parameters

Testing Principle

Vertical sample combustion in oxygen/nitrogen gas flow. Combustion time and oxygen percentage are measured to determine LOI.

Test Procedures

First: Prepare the accessories and test sample;

Place the test sample in the fixture;

Use a long hook to insert the fixture with the sample into the heat-resistant glass tube;

Turn on the instrument switch and access the LCD screen interface;

Purge with oxygen and nitrogen for 30 seconds each;

Set the oxygen concentration parameter;

Set the heating temperature;

Stop heating when the temperature inside the test tube reaches a certain level;

Ignite the sample with an ignition gun;

Start the timer;

Stop the timer when the flame reaches a certain mark;

Stop the gas supply and heating;

Save and view the data;

Remove the test sample and turn off the instrument to end the test.

Product Features

1.Integrated Structure with Industrial Design

Features an all-in-one construction with a modern industrial design, offering an elegant appearance and user-friendly operation.

2.Equipped with Two Mass Flow Controllers (MFCs)

Two high-precision MFCs are used to accurately control the mixing ratio of nitrogen and oxygen, ensuring convenient operation and precise gas regulation.

3.Automatic Closed-Loop Oxygen Concentration Control

Automatically achieves closed-loop control of oxygen concentration, enabling precise regulation of the oxygen level inside the combustion column.

4.Patented Gas Mixing Chamber Design

The specially designed gas mixing chamber ensures that gases are thoroughly mixed within a short period of time, resulting in more accurate and reliable test data.

5.Gas Diffusion Ring and Mixing Glass Beads

Equipped with a gas diffusion ring and mixing glass beads to ensure a more uniform gas flow at the outlet.

6.High-Temperature Resistant Quartz Glass Chimney

The combustion tube is made of heat-resistant quartz glass, while the independently designed end caps facilitate easy cleaning and maintenance of the glass tube.

7.Interchangeable Stainless Steel Specimen Holders

Supplied with both supported and unsupported stainless steel specimen holders, allowing convenient switching to accommodate different testing requirements.

8.Portable Igniter with Precision Needle Valve

Features a portable ignition device with a precision needle valve for accurate flame size adjustment.

9.Paramagnetic Oxygen Concentration Sensor

Equipped with a paramagnetic oxygen sensor capable of displaying oxygen concentration with an accuracy of ±0.1%. Compared with conventional electrochemical oxygen sensors, the paramagnetic sensor has no service life limitations, eliminating the need for frequent oxygen cell replacement. It also provides higher accuracy and faster response times.

10.Imported Ring-Type Heater

Utilizes an imported annular heater to efficiently preheat the mixed gas before it enters the combustion chamber.

11.Wide Temperature Control Range

The mixed gas temperature can be controlled from ambient temperature up to 400°C, meeting the requirements of both ambient and elevated-temperature oxygen index testing.

12.Temperature Column with Observation Function

The heating column allows operators to observe the specimen throughout the test while simultaneously providing high-temperature radiant heat.

13.Imported K-Type Armored Thermocouple with PID Control

An imported K-type armored thermocouple is used for temperature monitoring. Combined with PID automatic temperature regulation, the system maintains the set temperature within ±2°C.

14.PLC and Touchscreen Control System

A Programmable Logic Controller (PLC) integrated with a touchscreen interface enables digital setting of nitrogen and oxygen concentrations without repeated manual adjustments. Temperature parameters can also be preset and monitored with real-time feedback.

15.Optional PC-Based Control Software

An optional desktop computer and professional control software package provide comprehensive guidance throughout the entire testing process, while enabling test data storage, result output, and report generation.

Conclusion

In summary, the High-Temperature Oxygen Index Tester serves as a scientific and reliable method for evaluating the combustion performance of materials and plays a vital role in fire safety assessment. By simulating elevated-temperature environments, the instrument determines the oxygen index of materials under high-temperature conditions, providing a sound scientific basis for assessing their fire resistance properties.

At the same time, its high measurement accuracy, excellent stability, and intelligent operating interface make the testing process more convenient, efficient, and dependable. These advantages enable researchers and manufacturers to obtain precise and repeatable data while improving overall testing efficiency.With the continuous advancement of modern industry and technology, the application prospects of the High-Temperature Limiting Oxygen Index (LOI) Tester are expected to become even broader. It will continue to provide critical technical support for material research and development, quality control, product certification, and the formulation of fire safety standards, thereby contributing to the development of safer and more reliable materials across a wide range of industries.