Current status of fire-resistant hydraulic fluids meeting European underground mining standards

The European Mines Safety Commission was established in 1961 in response to a mining disaster in August 1956 at Bois du Cazier, Belgium. Hydraulic hoses were ruptured and the pressurized flammable hydraulic fluid was ignited, resulting in 267 deaths. A commission of technical experts from Europe was formed to recommend replacements for flammable oils in critical applications. Specifications were developed for fluids used in underground pumping systems and mining roof support equipment. The initial report was last updated in 1994 and is now known as the 7th Luxembourg Report. This document has been particularly important for the underground mining industry. The Report is in the process of being updated by conversion of the test methods and requirements to ISO standards. The 7th Luxembourg Report contains four categories of required testing: Fire resistance, technological properties, ecological properties, and toxicological properties. Approval testing must be conducted by a certified independent laboratory. This paper will discuss each of these categories and give examples of the tests required. Particular emphasis will be given to high water content mining hydraulic fluids and the problems encountered with corrosion resistance and emulsion stability. A new classification for water glycol fluids with lower water content has been added in recent years. An example will be shown of a fluid in this classification that meets all of the 7th Luxembourg requirements and provides excellent pump lubrication with no derating of the pump. Copyright © 2011 by ASTM International.