Polypropylene brushes are primarily used for sweeping which of the following?

Polypropylene brushes are specifically designed for use with coal or oil appliances. These materials are robust and effective at removing the heavier soot and debris that typically accumulate in chimneys fueled by coal or oil. Unlike softer brushes that may be preferred for more delicate fuel sources, polypropylene brushes can handle the tough, tar-like residues produced during the combustion of coal or oil, ensuring a more thorough cleaning and maintenance of the chimney system.

Chimneys associated with gas or electric sources generally produce less buildup and can often be cleaned with softer brushes, making the polypropylene brushes less suitable for those applications. Similarly, wood and pellet stoves create different types of residues that may require different brush materials, while charcoal and briquettes also produce specific combustion byproducts that may not necessitate the heavy-duty scrubbing provided by polypropylene. Therefore, the choice of polypropylene brushes for coal or oil systems aligns with their ability to effectively handle the abrasive residues encountered with these fuel types.