Fire gas analysis using the steady-state tube furnace

Syfte

The technical specification ISO/TS 19700 describes testing using a steady-state tube furnace (SSTF). The sample is slowly feed into the oven and as new material enters the combustion zone, there will be a continuously burning of the material in a steady state.

Metod

The combustion conditions are established by feeding the sample material into the furnace together with primary air for combustion. The combination of the material feeding rate, the primary air flow rate, and the furnace temperature decides the combustion conditions.

The fire stages replicated using the steady-state furnace are:

• Fire stage 1b – oxidative pyrolysis (350 °C);
• Fire stage 2 – well-ventilated flaming fires (650 °C);
• Fire stage 3a – small vitiated fires in closed or poorly ventilated compartments (650 °C);
• Fire stage 3b – post-flashover fires in open compartments (825 °C).

The nominal loading of the sample according to ISO/TS 19700 is 25 mg combustible material/mm with a feeding rate of 40 mm/min. The primary air flow is usually 10 l/min for well-ventilated flaming combustion, resulting in a material/air ratio of 100 mg combustible material/l air.

The smoke and gases are collected in a mixing chamber at the end of the furnace. The gas is mixed with secondary air (total flowrate is 50 l/min) and then collected for gas analysis according to ISO 19702 (FTIR) or any method provided in ISO 19701.

Leverans

A test report, in Swedish or English, is deliverd with the test results after testing.