What is preferable for the pressure reading on steam gauges?

The correct answer indicates that a pressure reading of 200% on steam gauges is preferable. This choice is relevant because steam gauges are often designed to provide readings that are well within the operational limits of a boiler system, allowing for a safety margin. When gauges read at or near their maximum capacity, there is a higher risk of inaccuracy and potential overpressure situations.

By using a gauge that measures up to 200% of the normal operating pressure, operators can better ensure that they are monitoring the system effectively without pushing the equipment to its limits. This capacity allows for fluctuations and surges in pressure, enabling operators to take corrective action if necessary, thus promoting safety and reliability in steam operations.

Other choices may suggest readings above or below what's considered optimal, which could imply that equipment is being operated at unsafe levels or that the operator may not have a clear understanding of the system's operational parameters.