What is the correct method for measuring small changes in vacuum?

The appropriate method for measuring small changes in vacuum is through the use of a micron gauge. Micron gauges are specifically designed to measure vacuum levels in precise units of pressure, such as microns or millimeters of mercury (mmHg). This level of sensitivity allows technicians to detect even minor fluctuations in vacuum, which can be crucial in applications like refrigeration, air conditioning, or vacuum systems where maintaining an optimal vacuum level is essential for proper operation and efficiency.

Unlike pressure gauges, which are typically designed for higher pressure readings and may not provide the precision needed for small vacuum changes, micron gauges are calibrated to measure low-pressure states accurately. Regular vacuum gauges, on the other hand, may provide a general indication of vacuum but lack the sensitivity necessary for detecting small variations. Using a thermometer is irrelevant in this context, as it measures temperature rather than pressure or vacuum levels. Thus, a micron gauge is the most reliable and effective tool for accurately assessing small changes in vacuum.