While compressors have oil pressure switches and/or dip sticks that enable the operator to check the oil level before it becomes lower than is safe or desired, it is advantageous for the operator to have a visual indication of this level. It may also be desirable to have a low level alarm.

These functions are accomplished by using a magnetic level gauge. These gauges are normally very short, on the order of 8 to 12 inches. The temperature will usually be on the high side and the specific gravity will be fairly low. However, a standard steel gauge is normally quite adequate.