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52 I ICT TODAY FIGURE 3: ASTM time-temperature curve and common materials melting point. Achievement of a T-rating is generally not required to pass the through-penetration firestop test; however, it is measured and listed as a reference. The purpose of the T-rating is to record when the firestop system reaches ≈325 o Fahrenheit (≈163 o C) above ambient room temper- ature on the non-fire side of the test assembly. Why is this relevant? This temperature mark is the estimated point where common combustible material, such as cotton, can spontaneously ignite without direct exposure to a flame. During a fire occurrence, an MEP penetration, particularly a steel pipe or copper cable, running through a floor could make contact with a combustible material and theoretically transmit enough heat to ignite it. However, in most situations, penetrating items that could conduct significant heat are located in a mechanical or electrical room and not directly exposed to these combustibles. How extensive are the ASTM and UL testing? Depending on the duration of the test, which is typically 1 to 4 hours, materials are subjected to temperatures between 1700 o Fahrenheit (≈927 o C) and 2000 o Fahrenheit (≈1093 o C). Per the standard ASTM E119 time-temperature curve shown in Figure 3, test materials are exposed to elevated conditions at an accelerated rate with furnace apparatus reaching 1300 o F (≈704 o C) in the first 10 minutes. This has an immediate impact on combustible construction materials. Aside from the details of fire testing, it is of critical importance to consider the general reference to the term "system." A routine question posed from the design and construction communities asks, "What is the average hourly rating of a typical firestop product?" The answer may be surprising—it is zero. There is no individual 0 2 4 6 8 Time, h E119 Time Temperature Curve Temperature, deg F Temperature, deg C 2400 2000 1600 1200 800 400 0 1200 1000 800 600 400 200 0 ASTM E119 TIME-TEMPERATURE CURVE • Aluminum—1220⁰ F (660⁰C) 1 • PVC plastic pipe— 41⁰ F (5⁰C) 2 • Fiberglass insulation—1100⁰ F (593⁰C) 3 Temperature at 10 minutes = 1300 °F (≈704⁰C) Approximate Melting Points: Sources: 1. NFPA Fire Protection Handbook, 18th Ed. Table 4-16A. Pg 4-183. 2. SFPE Handbook of Fire Protection Engineering, 1st Ed. Table 1-12.1. Pg. 1-166. 3. SSL I or II Fiberglass Insulation Specification Sheet, Owens Corning. 0 2 4 6 8 Time, h E119 Time Temperature Curve Temperature, deg F Temperature, deg C 2400 2000 1600 1200 800 400 0 1200 1000 800 600 400 200 0 ASTM E119 TIME-TEMPERATURE CURVE • Aluminum—1220⁰ F (660⁰C) 1 • PVC plastic pipe— 41⁰ F (5⁰C) 2 • Fiberglass insulation—1100⁰ F (593⁰C) 3 Temperature at 10 minutes = 1300 °F (≈704⁰C) Approximate Melting Points: Sources: 1. NFPA Fire Protection Handbook, 18th Ed. Table 4-16A. Pg 4-183. 2. SFPE Handbook of Fire Protection Engineering, 1st Ed. Table 1-12.1. Pg. 1-166. 3. SSL I or II Fiberglass Insulation Specification Sheet, Owens Corning. What is the average hourly rating of a typical firestop product? The answer may be surprising—it is zero.