ICC Commercial Mechanical Practice Exam

What kind of refuse must have a safety or explosion relief vent in systems conveying it?

1. Gaseous

2. Fine dust

3. Liquid

4. Combustible

The correct answer is: Combustible

A safety or explosion relief vent is necessary in systems that convey combustible refuse, as these materials can produce flammable and potentially explosive atmospheres. When combustible materials are processed or conveyed, there is a risk of dust accumulation or the formation of a flammable mixture with air. If ignited, this can lead to rapid combustion and potentially result in an explosion. The purpose of a safety or explosion relief vent is to provide a designated escape route for the rapidly expanding gases, thus preventing structural damage to the system and minimizing the risk of injury. In contrast, while gaseous refuse can also pose hazards, the concern for needing a vent might not be as critical as with combustible refuse. Fine dust, while potentially hazardous, specifically involves the accumulation and management of particulates, and may not always necessitate a vent unless it is known to be combustible. Liquid refuse primarily involves issues related to containment and spillage rather than explosion risk. Therefore, the critical factor in needing a safety or explosion relief vent is the presence of combustible materials that could result in a dangerous explosion if the system experiences a failure or blockage.