What is the dial arc for a non-mercury gauge of magnitude 5 psig?

The dial arc for a non-mercury gauge of magnitude 5 psig is indeed 270 degrees. This means that the gauge is designed to represent a pressure range that covers a substantial portion of the circular scale, which typically accommodates a safe operating range for the system it is measuring.

In the context of pressure gauges, the arc itself delineates the area of measurement, where 0 psig typically starts at the 6 o'clock position on the gauge. The 270-degree arc covers a significant portion of the gauge face that allows it to display pressures from 0 to a maximum defined by the manufacturer. This particular gauge can effectively indicate pressures from 0 up to a point that is less than or equal to 10 psig, and the remaining arc would not be used for readings, making it a practical design choice.

The reasons for the other options not being correct lie in their representations of pressure ranges. A 180-degree arc would not suffice for this application since it would limit the maximum pressure that could be accurately displayed. A 360-degree arc would be unnecessary and overly expansive for a gauge rated at 5 psig, as it would not allow for effective readability and could lead to confusion in interpreting the gauge. A