All single or combined mechanical exhaust systems must be __________ of all other exhaust systems.

The correct answer is that all single or combined mechanical exhaust systems must be independent of all other exhaust systems. This requirement is foundational for ensuring that each exhaust system operates effectively without interference from others.

Independence is crucial for several reasons. First, it prevents the potential for cross-contamination between different exhaust systems, especially in environments where hazardous gases or pollutants may be present. If systems were interconnected, it could lead to backflow issues or the mixing of exhaust streams, which can compromise indoor air quality and safety.

Moreover, having independent exhaust systems ensures that the performance of one system does not negatively impact another. For example, variations in pressure or airflow in one exhaust system could inadvertently affect another, leading to inefficiencies or failures in ventilation.

This independence aligns with the general principles of mechanical ventilation, which aim to maintain effective air circulation and remove contaminants in a controlled and reliable manner. Therefore, it is essential that exhaust systems be designed and installed as independent systems in compliance with the International Mechanical Code and other relevant standards.