STP1111

    Effects of Oxygen Concentration, Diluents, and Pressure on Ignition and Flame-Spread Rates of Nonmetals: A Review Paper

    Published: Jan 1991


      Format Pages Price  
    PDF Version (200K) 12 $25   ADD TO CART
    Complete Source PDF (11M) 12 $69   ADD TO CART


    Abstract

    The literature reviewed indicates that oxygen concentration, diluents, and pressure in combustion-test environments can influence the ignition and flame-spread rates of nonmetals. Increased oxygen concentrations result in easier ignition and higher flame-spread rates. The flame-spread rate is generally a non-linear function of oxygen concentration, indicating that different processes are controlling combustion at different oxygen concentrations. The effect of oxygen concentration is higher at the minimum conditions required for ignition and at near-extinction conditions. Diluents affect the ignition and flame-spread rates in oxygen/diluent mixtures due to their effects on the thermal conductivity, specific heat, and diffusivity of the mixtures. Helium, which has a higher thermal conductivity than nitrogen, was shown to be a better inhibitor of ignition processes. Nitrogen/oxygen environments, which have higher heat capacity and lower diffusivity than helium/oxygen mixtures, generally result in lower flame-spread rates. The data also indicates that increased test pressures generally result in easier ignition and higher flame-spread rates. However, higher pressures can affect ignition and flamespread in opposing ways by affecting the gas-phase kinetics of the combustion process. The effects of test pressure are more pronounced at minimum conditions for ignition or at near-extinction conditions.

    Keywords:

    polymers, nonmetals, ignition, flammability, flame spread, oxygen concentration, diluents, pressure


    Author Information:

    Hirsch, DB
    Chemical EngineerAerospace EngineerSenior Engineer, Lockheed-ESCNASA/JSCNASA White Sands Test FacilityLockheed-ESC, Las CrucesHouston, NMTX

    Bunker, RL
    Chemical EngineerAerospace EngineerSenior Engineer, Lockheed-ESCNASA/JSCNASA White Sands Test FacilityLockheed-ESC, Las CrucesHouston, NMTX

    Janoff, D
    Chemical EngineerAerospace EngineerSenior Engineer, Lockheed-ESCNASA/JSCNASA White Sands Test FacilityLockheed-ESC, Las CrucesHouston, NMTX


    Paper ID: STP17763S

    Committee/Subcommittee: G04.02

    DOI: 10.1520/STP17763S


    CrossRef ASTM International is a member of CrossRef.