What is a requirement for fuel supply cylinders located close to the exhaust system?

Answer: B — They must be shielded against direct heat

Fuel supply cylinders located close to the exhaust system must be shielded against direct heat to ensure their safe operation. The shielding serves as a protective barrier that prevents excessive heat exposure, which is crucial for maintaining the integrity and performance of the cylinders. Since high temperatures can compromise the structural integrity of the cylinder, leading to potential failures or leaks, this requirement is vital. Proper shielding ensures that heat generated by the exhaust system does not directly impact the fuel supply cylinders, thereby safeguarding against risks associated with overheating. This measure is part of best practices for the installation and operation of compressed natural gas systems, especially in vehicles where placement of components is critical for safety and efficiency. While other options might mention protective measures, such as insulation or fireproof containers, they do not specifically address the direct heat exposure from exhaust systems like shielding does.