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A Fire Retardant Froth Foam Seal Topping System for the U.S. Bureau of Mines Remote Mine Sealing System.

Wallhagen-RE; Douglas-SB; Monaghan-DA
NTIS: PB/286-988 Available for Reference At Bureau Libraries :79 pages
The froth foam seal topping system is part of a system for remote sealing of mine passages using fly ash transported pneumatically from the surface. Making the final 5 pct of the seal with a foamed- in-place fire retardant polyurethane reduces the required fly ash volume by 50 pct and provides a more reliable seal. Foam components are held at the surface under proper conditions of temperature and pressure, then conveyed down the borehole through individual hoses, and mixed at the bottom with a static mixer. The polyol component is premixed with fluorocarbon-12 which, when released from system pressure in the mixer, boils and causes the foam to expand. Difficulties in handling this particular foam formulation are offset by a flame spread index well below the 25 level by ASTM e-162 normally required for underground applications. Isocyanate, polyol (tdi), and catalyst are conveyed to the downhole package by three separate lines. Five additional lines operate the valving and convey solvent so that the mixer and package lines can be flushed immediately after foaming. The eight-hose bundle is provided in segments of several lengths so that borehole depths can be matched. Cast-in-place plastic cylinders hold the bundle together and transfer the weight of the hose through a special quick-release clamp to the crane's wire rope.
Publication Date
Document Type
CP; Final Contract Report;
Fiscal Year
NTIS Accession No.
NTIS Price
Identifying No.
OFR 113-78
NIOSH Division
Source Name
NTIS: PB/286-988 Available for Reference At Bureau Libraries
Performing Organization
Foster-Miller Associates, Inc.
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division