Protective clothing — Assessment of resistance of materials to molten metal splash
1Key Takeaways
This standard provides a method for evaluating the resistance of materials used in protective clothing against molten metal splashes. It outlines procedures for testing the performance of materials under specific conditions that simulate real-world exposure. The assessment includes determining the extent of damage caus…
2Expert Interpretation
The third edition of ISO 9185:2025 specifies in detail the test methods for the resistance of protective clothing materials to molten metal splash, covering specific test procedures for materials such as aluminum, copper, iron, mild steel and cryolite. It provides a scientific evaluation basis for industrial protective equipment through PVC sensor membrane damage assessment and metal splash index determination.
Technical Evolution and Core Changes of ISO 9185:2025
The third edition of the international standard ISO 9185:2025, "Protective clothing — Evaluation of the resistance of materials to molten metal splash," has undergone significant technical revisions based on the second edition published in 2007. This revision primarily addresses the update of PVC sensor membrane batches and the optimization of test methods, significantly improving the reproducibility of test results between laboratories. The technical evolution of the standard is primarily reflected in the following key improvements: The new version of the PVC sensor membrane has been validated through global interlaboratory comparison tests, demonstrating comparable performance to previous batches while exhibiting improved stability. Clarified criteria for determining damage to the PVC sensor membrane have been added, with the addition of a quantified indicator for pinholes ≥5 mm in width or ≥1 mm in diameter. The use of a metal support plate has been introduced for all metal tests except aluminum and cryolite. Furthermore, a new performance-level-based test procedure has been added, providing a more flexible approach for verifying product compliance with the standard. The core test principle of the ISO 9185:2025 standard is to assess damage caused by heat penetration by pouring a fixed amount of molten metal onto an inclined specimen using an embossed thermoplastic PVC sensor membrane placed behind the specimen. The adhesion of the metal to the specimen surface is recorded during the test, and iterative testing is used to determine the minimum metal mass required to cause membrane damage.
| Test equipment components | Technical specifications | Precision control | Application considerations |
|---|---|---|---|
| Pouring device | Drive shaft rotation rate (36.0±2.5)°/s | Angular deviation ≤0.2s/90° | The molten metal pouring point must be located on the drive shaft rotation axis |
| Specimen holder | 160mm×248mm rectangular needle frame | Dimension tolerance ±2mm | Four corner positioning holes ensure full contact between the sample and the PVC film |
| Metal Support Plate | 1.5-3mm thick steel plate | 260mm×100mm±2mm | Determine whether to use according to Table A.1 (not used for aluminum and cryolite testing) |
| Temperature Probe | Measuring range up to 1650℃ | Maximum allowable error ±10℃ | Measurement must be made after stirring at least 1cm below the molten metal surface |
Key Test Parameters and Material-Specific Conditions
The standard sets specific test conditions for different molten metals and cryolite. These parameters directly affect the accuracy and comparability of test results. The pouring height, specimen tilt angle, and use of the metal support plate must be strictly adjusted according to the test material.
| Test Material | Pouring Temperature (℃) | Pouring Height (mm) | Specimen Angle (°) | Metal Support Plate |
|---|---|---|---|---|
| Aluminum (≥99.5%) | 780±20 | 225±5 | 60±1 | Not used |
| Copper (≥99%) | 1280±20 | 225±5 | 60±1 | Use |
| Iron (≥93%) | 1400±20 | 225±5 | 60±1 | Use |
| Low carbon steel | 1550±20 | 225±5 | 60±1 | Use |
| Industrial grade cryolite | 1120±20 | 300±5 | 70±1 | Not used |
Notably, due to its lower viscosity, the cryolite test employed a different parameter combination: the pouring device rotation rate was reduced to (18.0±1.5)°/s, the specimen angle was increased to 70±1°, and the pouring height was raised to 300±5mm. These adjustments ensured comparability of test results for materials of varying viscosities.
PVC Sensor Membrane Damage Assessment Standard and Quality Control
PVC sensor membrane is the core component of the test, and its quality control is directly related to the reliability of the test results. The standard specifies a unit area mass of (300±30)g/m² for the film and specifies thermal property calibration methods in Normative Annex B. Damage criteria include: smoothing or modification of the surface before and after embossing, with a total width of at least 5 mm; or pinholes with a diameter of at least 1 mm. For visual changes that occur in the form of discrete points, damage is considered when the total width of each point on any horizontal cross-section exceeds 5 mm. Experience with cryolite testing indicates that damage can be defined as less than 5 mm in width but greater than 10 mm in length. The PVC sensor membrane must be calibrated within six months of testing according to the method in Appendix B to ensure that the central area of the embossing is smoothed or modified at (166 ± 2) °C and smoothed or modified at (195 ± 2) °C. Storage in a cool, dark place is recommended, as loss of plasticizer may cause film properties to change over time.
Test Procedure and Metal Spatter Index Determination
The standard provides two test procedures: an iterative test procedure and a performance level-based test procedure. The iterative test procedure systematically adjusts the metal mass to accurately determine the minimum metal mass that causes damage to the PVC sensor membrane.
Specific steps for iterative testing: Initially, use approximately 50g of metal for testing. If there is no damage, increase the amount by 50g each time and repeat the test; if damage occurs, reduce the amount by 10g and repeat the test; finally, the metal spatter index is determined through four consecutive non-damage tests. This index is the arithmetic average of the minimum metal mass that causes damage and the highest metal mass in the four non-damage tests.
The performance level-based test procedure is suitable for verifying product standard compliance. Performance levels can be selected based on experience or customer expectations, and the final rating of the material can be confirmed through testing between different levels.
Operator Safety and Test Environment Control Requirements
Operator safety is the primary consideration during testing. The standard requires operators to wear protective clothing and equipment that conforms to ISO and CEN standards to prevent accidental splashing of molten metal or cryolite. Risk assessments should also consider protection against smoke and/or toxic fumes.
Special Warning: In addition to the molten metal splash hazard, some metals can spontaneously ignite and produce toxic fumes when heated in air. Testing the material resistance of these metals requires additional safety measures. Operators must fully understand the properties of the cryolite and all molten metals used.
Test Environment Control: The specimens must be conditioned at a temperature of 20±2°C and a relative humidity of 65±5% for at least 24 hours. The test environment should be essentially free of drafts, with a temperature of 10-30°C and a relative humidity of 15-80%.
Standard Implementation Recommendations and Industry Application Guidance
ISO 9185:2025, as a test method standard, does not itself specify material performance levels, but it does enable comparison of materials' barrier properties under specific molten metal and cryolite conditions. Key points to note during implementation:
Equipment Calibration and Verification: Regularly verify the rotation rate and angular accuracy of the pour device to ensure a constant angular velocity of (36.0±2.5)°/s; for cryolite testing, adjust to (18.0±1.5)°/s. The temperature measurement system requires regular calibration to ensure measurement accuracy of ±10°C.
Specimen Preparation and Handling: Prepare seven specimens using a template, with the long side in the machine direction (the direction is not important for materials such as leather). The template is used to mark the location of the pinholes in the specimen holder and has a diameter of approximately 2mm. Cut the same amount of PVC sensor film but do not mark the pinhole location.
Test Invalidation Conditions: The test should be declared invalid and repeated using the same metal mass if the pouring impact drifts horizontally on the specimen, metal flows down the side of the specimen or within 25mm of the upper edge of the impact, any molten metal does not first hit the specimen, the metal is not completely melted when poured, or the PVC film ignites due to metal solidifying on the specimen support.
Extended Industry Applications: While the standard provides specific test procedures for aluminum, cryolite, copper, iron, and mild steel, the test principles are applicable to a wider range of hot-melt materials, provided appropriate measures are taken to protect the test operator. It should be noted that good resistance of a material to pure molten metal does not guarantee good performance against any slag that may be present during the manufacturing process.
This standard is used in conjunction with product standards such as ISO 11612 "Protective clothing — Heat and flame resistant clothing — Minimum performance requirements" to provide a scientific basis for the selection and quality control of personal protective equipment in industries such as metallurgy, casting, and welding. During implementation, appropriate protective performance requirements should be formulated in combination with specific industry characteristics and risk assessment.