Which of the following pipe types is NOT used for medical-surgical vacuum systems?

The correct choice refers to ASTM B316, which is not typically associated with materials used in medical-surgical vacuum systems. This specification pertains to a type of stainless steel often used in specific industrial applications, but it does not align with the standards required for the construction of piping systems that are specifically designed for the vacuum needs of medical-surgical environments.

Medical-surgical vacuum systems require materials that not only support the handling of medical gases and are resistant to corrosion but also comply with strict industry standards to ensure safety and compatibility with hospital infrastructure. ASTM B819 and ASTM B280, for example, detail the properties of copper and copper alloys used for medical-gas systems, while stainless steel is widely accepted for its durability and resistance to contamination.

Thus, within the context of applications for medical-surgical vacuum systems, ASTM B316 does not meet the requirements or specifications typically mandated for such systems, making it the appropriate answer to the question.