What defines a low-pressure DOT cylinder?

A low-pressure DOT cylinder is specifically defined as any cylinder with a maximum allowable working pressure (MAWP) below 500 PSI. This classification is important because it helps to establish the regulations and standards that apply to the manufacturing, testing, and usage of pressure vessels within the context of safety and compliance.

Cylinders operating under 500 PSI are subject to different regulatory standards compared to high-pressure cylinders, which can have pressures exceeding that threshold. Understanding this distinction is critical for proper handling, storage, and maintenance of these cylinders to ensure safety during use, particularly in applications involving fire safety equipment like extinguishers.

The other options present higher pressure thresholds, which do not align with the definition of low-pressure cylinders according to the Department of Transportation (DOT) regulations. Recognizing the specific limits for classification helps in adhering to safety protocols when dealing with various types of cylinders.