Indirect atmospheric-type vaporizers of less than 1 quart capacity shall NOT be required to be equipped with __________.

Indirect atmospheric-type vaporizers function primarily by exploiting ambient heat to vaporize liquid propane. When considering safety and operational requirements, pressure relief valves are crucial for equipment that may operate under significant pressure levels, ensuring that any excess pressure is safely released. However, vaporizers with less than 1 quart capacity are generally not expected to reach pressure levels that would necessitate a pressure relief valve for safe operation.

For larger capacity systems, pressure relief valves play a key role in protecting against the risks associated with pressure build-up. In smaller units, the design and operational parameters often inherently limit the potential for dangerous pressure levels, diminishing the necessity for this specific safety feature.

Temperature gauges, flow meters, and shutoff valves serve important roles in monitoring performance, managing flow, and ensuring safe operations, which is why they are still often required in these systems. In direct contrast, the lower pressure situations in small capacity vaporizers make pressure relief valves unnecessary, as they are not likely to pose the same level of risk as larger systems.