Basic Enlisted Submarine School (BESS) Test 2 Practice 2026 - Free Submarine School Practice Questions and Study Guide

A 125 psi header is designed to deliver air to equipment that operates anywhere up to its maximum of 125 psi. Because devices tied to this header are specified to run within a pressure range that can start around 21 psi and go up to 125 psi, the statement that it supplies loads requiring 21–125 psi reflects how this header is used in practice. The other options describe specifics about system layout or pressure ranges that aren’t inherent to what a 125 psi header does: it isn’t defined as being fed from a particular air bank, it isn’t described as backing up a higher-pressure 700 psi header, and it isn’t intended for only very low-pressure loads like 1–20 psi.