I am not an expert on the subject of fire ratings, but I have been exposed to it over the years and sooner or later some of it sinks in. There are several agencies that oversee this area including and not limited to the International Building Code (IBC), marine agencies such as the US Coast Guard (USCG), NFPA, ASTM and UL. The IBC, NFPA and UL tend to have an international presence with many countries that subscribe to their codes. ASTM tends to address actual testing methods like they do for engineering codes.
Almost all markets have some needs for fire rated (FR) composites. I will address the industrial and architectural markets here, although the other markets have similar needs from marine to transportation to consumer products.
A common test that is referenced in project specifications is ASTM E84. There are a couple different classes such as Class 1 and Class 2 (sometimes referred to as Class A, B or C). When a FR code is specified, it typically is Class 1. The important criteria here is the Flame Spread and the Smoke Index. To meet Class 1 flame spread the material must meet the 25 index and for smoke, the 450 index.
Here is where it gets interesting. Many FR FRP materials meet the flame spread figure, but not the smoke index. This is especially true for isophthalic resins (ISOFR) which are common with the FRP pultrusion makers. Not that they do not have a solution for a low smoke product….some of them do have a product. I don’t know for sure why it is uncommon to find low smoke resins, but it is tough to pass the test. The testing can also be expensive. ASTM testing tends to be fairly reasonable with some exceptions while the NFPA has very tough guidelines and tend to have very expensive tests costing $20K or more. Its also possible that for most pultruded applications, the product is outside such as on buildings or at industrial sites like water plants.
The resin manufacturers tend to offer testing on their own resins. This is very helpful to a laminate manufacturer. It should be noted that resin makers like Polynt offer both gel coat and standard resins with tested FR ratings. And finally, FR is available in most of the common resin types like polyester, epoxy and vinyl ester.
So next time you see a product that lists a feature as Class 1, don’t assume it meets both index and smoke. You can count on it meeting the Flame Spread, but not necessarily the Smoke Index. In the future we will address the NFPA and their standards.