What range of gauge magnitude should not exceed 3 psig?

The correct answer lies within the understanding of pressure measurement and the specific requirements for pressure gauges in high pressure boiler operations. Pressure gauges need to be calibrated to ensure they accurately reflect the pressure and operate within safe limits.

In this context, the option stating "1/10" increments @ 4.5 psig to 6 psig" offers the most precise range of measurement without exceeding the 3 psig threshold that is critical for safety and operational efficiency. The 1/10" increment allows for finer adjustments and readings, which is especially important in maintaining the integrity of high-pressure systems where slight variations can have significant implications.

Using pressures above 3 psig could indicate a risk in safety protocols. Therefore, ensuring that the gauge operates within the specified parameters with small increments helps in monitoring and keeping track of any changes in pressure effectively—important for maintaining the safe operation of the high-pressure systems.

The other options, with their larger increments, do not provide the same level of accuracy and could lead to less reliable measurements, which would not be suitable for environments where precise pressure control is critical.