A master gauge is a standard gauge used to check the accuracy of other measuring tools or gauges that are used in various manufacturing processes. It serves as a reference standard that ensures the precision and consistency of other gauges, which in turn guarantees the quality and correctness of measurements on the shop floor. Master gauges are typically highly accurate and are used to verify the calibration of different measuring instruments used in production or quality control.
Explanation of other options:
- (1) A new gauge refers to a measuring instrument that is recently manufactured or put into service. It is not necessarily a reference for checking the accuracy of other gauges.
- (2) The international reference standard is a global reference used in many scientific and technical fields to maintain measurement consistency across countries, but it's not the definition of a master gauge.
- (4) A gauge used by experienced technicians refers to the person operating the gauge rather than the function or purpose of the gauge itself.
Thus, the correct answer is (3), as the master gauge is specifically used to ensure the accuracy of gauges used in shop floors.