HIGH TEMPERATURE DISPOSABLE DIESEL EXHAUST FILTER ELEMENTS
One of the most effective ways of reducing the exposure of underground workers to diesel particulate matter (DPM) contained within diesel exhaust emissions is to fit the equipment with a disposable diesel exhaust filter.
Disposable DPM filters have been fitted and used on diesel equipment in the underground mining industry throughout the world for quite a number of years. The Australian underground coal mining industry began using disposable DPM filters to varying degrees as far back as the early 2000’s.
Historically the disposable DPM filters used on underground coal mining equipment in Australia have a short operational life. The reason for this has long been believed by equipment operators to be due to the fact that they are installed after a wet scrubber which saturates the exhaust stream and therefore the filter element with water causing the filter medium to swell or become saturated with water. The result being the exhaust filter blocks in a short time not because it is loaded with diesel particulate but rather because it is saturated with water and chokes’ off the passage of exhaust gases through the filter element.
In the USA the underground mines and their legislators and regulators have been actively managing the same issues in regards to DPM and its effective filtration for many years and since before 2004 they began evaluating and using high temperature disposable diesel particulate filter elements in their underground coal mines.
These glass fibre based filter elements are commercially available and work effectively in both wet and dry scrubber systems on diesel engine systems approved for use in underground coal mines.
In a recent trial in an underground coal mine in Australia the high temperature disposable DPM filter manufactured and supplied by Filter Services and Testing Incorporated (FST) in the USA had an operational life up to 6 times longer than currently available DPM filters in Australia.
MSHA has an list of various models of disposable filters for use in underground coal mines within the U.S. FST filters are manufactured from the same filter media materials and the same standards as those found to be compliant with 30 CFR Section 72.500,72.501, and 72.502 of the MSHA compliance regulations.
The rules and test protocols used by MSHA are very stringent and thorough. They are all publically available. The tests which were performed on filters to support the DPM regulations are described in Part 7 subpart E of Title 30 Code of Federal Regulations. http://www.msha.gov/30cfr/7.0.htm and http://www.msha.gov/30cfr/7.89.htm
These filters are rated to a maximum operating temperature of either 302°F (150°C) or 650°F (343°C) depending upon the filter sealing arrangement that is used. At 302°F the filters are rated 95% efficient and at 650°F they are rated at 85% efficient.
In response to questions raised by some in regards to the suitability of the FST filters to be used on diesel equipment in operation in underground coal mines we have attempted to answer the commonly asked questions and provide direction to the facts and studies that support these answers. (Refer to FAQ)