HVAC - EPA Certification Practice Exam

The primary function of a mercury barometer is to measure atmospheric pressure. This instrument operates on the principle that changes in atmospheric pressure will affect the height of mercury in a column. When atmospheric pressure increases, it pushes the mercury up the tube, while a decrease in pressure allows the mercury to drop. This provides a direct measurement of pressure in terms of millimeters of mercury (mmHg) or other units. Understanding atmospheric pressure is crucial in various fields, including meteorology and HVAC, as it influences weather patterns and system performance.

In contrast, measuring wind speed, humidity levels, or temperature requires different types of instruments, such as an anemometer for wind speed, a hygrometer for humidity, and a thermometer for temperature. Each of these tools is specifically designed to measure their respective environmental parameters, highlighting the unique purpose of a mercury barometer in gauging atmospheric pressure.