ISO 20823 Determination of Flammability Properties of Fluids in Contact with Hot Surfaces - Manifold Ignition Test

The ISO 20823 “Oil and related products – Determination of flammability properties of fluids in contact with hot surfaces – Manifold ignition test” standard, published by the International Organization for Standardization (ISO), describes a test method for determining the relative flammability of fluids when in contact with a hot metal surface at a constant temperature. However, it is also possible to measure fluid ignition temperatures by adjusting the manifold temperature. This method is primarily used to evaluate the ignition resistance of fire-resistant hydraulic fluids, which are by definition difficult to ignite. It can also be used with other types of fluids that are more flammable at lower surface temperatures, but this can significantly increase the hazards of this procedure.

In principle, 10 ml of test liquid is dripped from a predetermined height and at a specified rate into a tube heated to 700 degrees or another temperature in series. The resulting spray is examined for flash or burning both on and after dripping from the tube.

Unless otherwise specified, samples should be taken in accordance with the procedures specified in ISO 3170 or an equivalent standard. Laboratory samples should be thoroughly mixed by vigorous shaking for 30 seconds before taking the test sample. The test sample should not be filtered, but any air bubbles that may arise during mixing should be allowed to escape from the liquid before testing.

In the world of high-risk industrial operations where machinery whizzes under extreme pressures and temperatures, safety is a lifeline. A hydraulic system is at risk in a steel mill or an offshore oil platform where a single spark from a hot surface can ignite a fluid and turn a routine maintenance check into a potentially catastrophic fire. This is where ISO 20823 and similar standards come into play, offering a rigorous framework for assessing and mitigating such risks.

The ISO 20823 standard includes a specific test method for evaluating the flammability of petroleum-based and related liquids when they come into contact with scorching metal surfaces.

Manifold ignition testing is a meticulously designed laboratory procedure that simulates industrial hazards. The basic steps of this test are as follows:

• Device setup: The heart of the test is a heated metal manifold, a simulated hot surface resembling an engine exhaust component, usually made of stainless steel. This manifold is electrically heated to a precise and constant temperature (typically around 600-800 degrees, adjustable to specific needs). It is mounted in a ventilated enclosure to safely contain any ignition events.
• Liquid application: The test fluid (hydraulic oil, lubricant, or a fire-resistant derivative based on phosphate ester) is atomized or sprayed onto a hot manifold. This simulates accidental leaks or sprays in machinery. The fluid makes controlled contact with the surface, with variables such as droplet size, flow rate, and exposure time standardized to ensure repeatability.
• Ignition observation: Observers monitor ignition: does the liquid ignite on contact, how quickly does it ignite, does it burst into flames? The test measures relative flammability by categorizing liquids according to their tendency to ignite. By gradually lowering the manifold temperature, technicians can determine the threshold at which the liquid bursts into flames, i.e., the exact ignition temperature.
• Data analysis and reporting: Results are generally expressed quantitatively as a non-flammability threshold or ignition index. Liquids that resist ignition at higher temperatures receive better scores, indicating superior fire safety. Accuracy is important: the standard mandates multiple (usually five) trials to account for variability and statistical analysis to validate the results.

Unlike open flame tests (e.g., ISO 15029 standard for spray ignition), the manifold approach focuses on surface contact, a common type of failure in turbocharged engines or hydraulic presses. This is particularly vital for water-glycol or phosphate ester fluids used in high-risk environments where even a momentary failure can escalate to dangerous levels.

The ISO 20823 standard is a cornerstone of compliance and innovation in fire-prone industries. Key points include:

• Hydraulic systems: In heavy machinery such as excavators or aircraft controls, fire-resistant fluids must pass this test to meet standards such as EN ISO 12922. This ensures that the systems can operate near hot areas without spontaneous combustion.
• Aerospace and defense: This standard, referenced in military manuals such as the MIL-HDBK-510 standard for fuel certification, helps qualify fluids for jet engines and electro-hydraulic controls.
• Energy and manufacturing: Oil refineries, power plants, and steel mills use lubricants to shield against hazards such as molten metal splashes or boiler exhaust.

Beyond direct applications, the ISO 20823 standard also influences product development. Liquid manufacturers repeat formulations to improve flame resistance, add antioxidants or synthetic bases, and often use the phrase “ISO 20823 compliant” in their data sheets.

This standard prevents potential damage by isolating high-risk liquids early. From an environmental perspective, safer liquids mean fewer spills and emissions, aligning with sustainability goals.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "ISO 20823 Petroleum and related products - Determination of flammability properties of fluids in contact with hot surfaces - Manifold ignition test" standard.