For construction materials and decorative products exported to the Italian market, UNI 9177 is the core standard for determining fire performance. Italian fire safety regulations mandate that materials used in public spaces must be tested and certified according to this standard.
This article first analyzes the definition and general classification system of UNI 9177, and then provides an in-depth technical interpretation of the testing methods specifically for textiles (curtains, wall coverings, upholstery fabrics).
What is the UNI 9177 Standard?
UNI 9177 (Reaction to fire. Classification of combustible materials) is the overarching specification in the Italian national standard system regarding the “classification of reaction to fire for combustible materials.” It does not prescribe specific testing procedures itself, but rather serves as a set of classification rules.
The function of this standard is to aggregate experimental data from various specific test standards (such as UNI 8456, UNI 8457, UNI 9174, etc.), comprehensively evaluate the combustion characteristics of the material under specific conditions, and ultimately assign the material a legally recognized fire rating.
Scope of Application
As a foundational standard, UNI 9177 applies widely to various combustible materials used in construction and interior decoration, not limited to a single category. Its primary scope includes:
- Textiles & Soft Furnishings:ย Curtains, stage drapes, wall fabrics, upholstered furniture.
- Flooring Materials:ย Carpets, wood flooring, PVC flooring, rubber flooring, artificial turf.
- Architectural Finishes:ย Wall panels, ceilings, acoustic panels, partition materials.
- Other Industrial Materials:ย Insulation materials, plastic films, display materials.
Italian Fire Classification System
According to the UNI 9177 standard, combustible materials are divided into 5 classes based on their fire performance. For fire safety inspections in public spaces (such as hotels, malls, theaters, schools), the requirements are extremely strict.
| Class (Classe) | Technical Definition | Application Compliance |
|---|---|---|
| Classe 1 | Difficult to Ignite | Highest Level. Wall, floor, and hanging materials in public spaces are typically mandated to meet this level. |
| Classe 2 | Moderately Difficult to Ignite | Restricted application. Allowed only in certain low-risk areas or specific types of flooring. |
| Classe 3 | Combustible | Ordinary wood typically falls into this category; usage is restricted. |
| Classe 4 / 5 | Easily Flammable | Strictly Prohibited. Forbidden for use in any public gathering spaces. |
Note: Classe 0 refers to non-combustible materials (such as concrete, metal, glass) and falls outside the scope of UNI 9177 classification.
Core Testing Methods for Textiles
For textiles (specifically curtains and decorative fabrics), achieving a UNI 9177 Classe 1 rating typically requires testing against the following two categories of standards and a comprehensive evaluation of both results.
1. Small Flame Test (UNI 8456 / UNI 8457)
These tests aim to evaluate the combustion reaction of textiles when exposed to a small ignition source (such as a match or lighter). This is the most critical aspect of textile testing, primarily examining the material’s ignitability and dripping characteristics.
UNI 8456 (Double-sided Combustion):
Applicable to vertically hanging materials where both sides may be exposed to air, such as curtains and drapes. During the test, the flame is applied to both the surface and the edge of the sample, and both the front and back sides must be tested.
UNI 8457 (Single-sided Combustion):
Applicable to materials backed by a substrate, such as wall coverings or carpets. During the test, the flame is applied to only one surface of the sample.
Key Performance Indicators:
- Flame Spread Speed: How fast the flame moves across the sample surface.
- Damaged Length: The extent of material destruction caused by combustion.
- Dripping Behavior:ย Observing whether molten material drips during combustion. If flaming droplets are produced, the material is immediately deemed non-compliant.
2. Radiant Panel Test (UNI 9174)
This test simulates the behavior of materials under the influence of high ambient heat radiation during the middle to late stages of a fire. It evaluates the flame propagation capability of the material when baked by high temperatures without direct contact with a large ignition source.
Test Principle:
The sample is placed horizontally (carpet) or vertically (wall covering/curtain) and exposed to a high-temperature radiant panel. Simultaneously, a small pilot flame is applied to one end of the sample.
Key Performance Indicators:
- Flame Propagation Speed: The rate at which the flame spreads along the sample surface aided by radiant heat.
- Damaged Area: The final size of the burned area.
In-Depth Comparison: UNI 9177 vs. International Standards
Textile exporters often face issues regarding mutual recognition of standards. The table below details the differences between UNI 9177 and major European and international standards.
| Standard System | Corresponding Class | Core Testing Differences | Acceptance in Italy |
|---|---|---|---|
| UNI 9177 (Italy) | Classe 1 | Sensitive to Dripping. Comprehensively examines small flame ignition and radiant heat spread; strict restrictions on flaming droplets. | Mandatory. The required standard for Italian public works projects. |
| EN 13773 (EU) | Class 1 | Based on ISO 6940/6941, primarily examines ignitability and vertical flame spread. | Limited. Italian law gives priority to national standards; most owners do not accept certificates based solely on EN standards. |
| DIN 4102 (Germany) | B1 | Chimney Effect. Focuses on vertical burn height. Tolerance for dripping is slightly higher than the Italian standard. | Not Interchangeable. Even polyester fabrics that pass B1 often fail UNI 8456 due to dripping issues. |
| NF P 92-503 (France) | M1 | Electric Burner/Thermal Decomposition. Extremely severe test conditions, focusing on non-flammability. | Not Interchangeable. Although M1 has high technical requirements, it cannot legally replace a UNI certificate for administrative compliance. |
| BS 5852 (UK) | Crib 5 | Wood Crib Source. Specific to furniture; uses a high-intensity ignition source. | Not Interchangeable. The Italian furniture standard UNI 9175 (1IM) requires testing with specific standard foam; the principles differ. |
Expert Material Recommendations (Textiles)
Based on the testing characteristics of UNI 9177, the following technical points are recommended during the textile R&D and production phases:
- Polyester Fiber Modification:ย Droplets produced by ordinary polyester during combustion cannot pass the UNI 8456 test.ย IFR (Inherently Flame Retardant) chipsย must be used to ensure the fabric shrinks and chars when exposed to fire, avoiding the creation of flaming liquid droplets.
- Wash Durability for Natural Fibers:ย Cotton and linen fabrics require flame retardant finishing. Since laboratory tests typically include a pre-wash procedure, the flame retardant formulation must be capable of withstandingย 3-5 wash cycles.
- Composite Structure for Upholstery:ย When conducting Classe 1IM (UNI 9175) certification, if the fabric is too permeable, gases from the burning foam can penetrate the fabric and ignite the surface. It is recommended to apply aย flame retardant back-coatingย to lightweight fabrics to block these gases.
FAQ
Q: Can UNI 9177 testing be conducted in China?
A:ย Preliminary testing can be performed, but it is difficult to use for official administrative applications. The Italian Ministry of Interior typically only recognizes official reports issued by laboratories on its authorized list (the vast majority of which are located in Italy). It is recommended to conduct pre-testing domestically to reduce risk, and then send samples to a designated Italian laboratory.
Q: Are there special requirements for testing Velvet fabrics?
A:ย The key lies in theย pile direction. In vertical flammability tests, there is a significant difference in burn speed between the “with-nap” and “against-nap” directions. Laboratories will typically test both directions and use the worst result as the final score. R&D should fully consider the impact of pile density on flame spread.
Q: Is smoke and toxicity testing required for curtain fabrics?
A:ย It is generally not mandatory. UNI 9177 primarily focuses on flame spread and physical combustion characteristics. Unless the project falls under rail transit, marine (IMO standards), or specific underground spaces, ordinary hotel curtains usually do not need to provide smoke density and toxicity reports.