What is the required size for the outlet of a blowoff tank?

The correct answer is based on the engineering principles that govern blowoff tank design to ensure efficient operation and safety. The size of the outlet is critical for managing the flow of water and steam that may occur during blowdown processes.

Choosing an outlet size that is two times the diameter of the blowdown piping allows for adequate drainage capacity and minimizes the chances of creating backpressure in the system. This increased diameter helps ensure that the fluids can exit the blowoff tank quickly and efficiently, reducing the risk of any pressure buildup which can be hazardous.

In the context of blowoff systems, it is also vital for the outlet to accommodate potential surges in flow during blowdown operations. A properly sized outlet, therefore, is an essential feature for maintaining system integrity and operational safety.

The other options, including specific measurements for internal or external diameters, do not provide the necessary flexibility for different piping configurations and operational demands that are outlined in industry standards. These standards emphasize that the outlet size should primarily be determined based on the diameter of the blowdown piping to ensure compatibility and performance.