No discussion about OHV sound and mufflers would be complete without information about spark arresters. Using spark arresters is a very good practice.
How Spark Arresters Work
Spark arresters work on the principle of trapping or pulverizing carbon particles that have a diameter greater than 0.023 in. Although they are not always 100 percent effective, a properly installed and maintained spark arrester will significantly reduce the risk of fire. The most common type of spark arrester is the screen type design, it will trap carbon particles in the exhaust system. A Screen Type works by screening the larger carbon particles out of the exhaust. Other designs utilize discs or a turbine design that work by trapping & through centrifugal force. The heavier carbon particles are thrown against the inside walls of the arrester and pulverized, then directed into a trap.
The most common types use a screen or a disc design. In a disc-type design, additional discs can be added to reduce backpressure and increase exhaust flow. (The use of a spark arrester may not minimize sound output. The addition of discs in a disc type exhaust system usually increases sound output.)
Currently, a significant number of States, Municipalities, Federally managed lands, and all USDA Forest Service regions require that all internal or external combustion engines must be equipped with a spark arrester that meets the requirements established by the SAE Standard J335 or USDA Forest Service Specification 5100-1. The Code of Federal Regulations, 36 CFR 261.52, and orders written by USDA Forest Service explain the requirements. USDA Qualified spark arresters must have external markings for identification that include design type and traceable information to the USDA Spark Arrester Guide publication.
For more information on spark arresters:
- United States Department of Agriculture
- Forest Service: http://www.fs.fed.us/t-d/programs/fire/spark_arrester_guides/
- National Wildfire Coordinating Group
- Fire Equipment Working Team: http://www.nwcg.gov/
- SAE: http://sae.org (spark arrester technical standard)