A spark arrestor
is a device intended to prevent combustible materials, usually sparks
or other tiny flaming debris
, from escaping into areas where they might start fires.
They are most commonly used in conjunction with motor vehicles (inserted into the muffler), as well as improving safety within fireplaces, and various electrical equipment. Often, a spark arrestor mimics a net fashioned from tightly interwoven wire gauze built to resist bits of ash, sparks or other such dangers.
Steam locomotives, especially when designed for burning wood fuel, were often fitted with large spark-arresting chimneys, called "balloon stacks" in the USA. Portable engines were also frequently equipped with spark arrestors since many of them were designed to burn wood.
Large power station boilers are commonly fitted with electrostatic precipitators.
Internal combustion engines
The spark arrestor is a part of the exhaust system and is mainly applied with diesel engines
. These diesel engines for example in generator sets, ship engines and on-/offshore activities are used.
They are also used on the mufflers of off road vehicles. In places where forest fires can be caused by sparks from off road motorcycle and all-terrain vehicles, spark arrestors may be required and forest rangers may cite violations.
Spark arrestors are also fitted to the top of a flue
(or a chimney pot
) to prevent floating embers from a fire (particularly one burning wood) setting light to a flammable roofing surface (shingle, thatch, or bitumen-felt) or falling onto combustible material on the ground. Such a spark arrestor typically consists of a double layer of metal mesh
, which catches the ember and allows the flue gas to escape.
- Main article: Electric arc
The function of the spark arrestor is to catch glowing particles which are entrained in the exhaust gas current. There are several ways to fulfill this function, the primary ones are discussed here.
With this type of spark arrestor the gases will turn around. Because the sparks (glowing particles) are heavier than the exhaust gases the particles will move themselves to the outside of the pipe under the influence of the centrifugal force. The spark arrestor ensures that the heavier particles arrive in the barge.
The vanes principle seems much on that of the crosspipe principle. The gases must pass the vanes, because the particles are relatively heavier they are swung to the outside of the spark arrestor. With this process they arrive in a spark bucket.
A fine mesh that catches any loose debris and keeps flames from exiting the mufflers.
- Main article: Scrubber
- Main article: Electrostatic precipitator
San Dimas Technology and Development Center of USDA Forest Service is the facility that tests the spark arrestors in the USA.