Final answer:
A compound pressure gauge can measure pressure in Pascals (Pa), Kilopascals (kPa), Pounds per square inch (psi), and Atmospheres (atm). Pascals and kilopascals are part of the International System of Units (SI), while psi and atm are also widely used.
Step-by-step explanation:
A compound pressure gauge for the low side of the system can measure pressure in various units, but the most commonly used units for such measurements are:
The proper SI unit for pressure is the pascal (Pa), where 1 Pa = 1 N/m². However, because a pascal is a very small amount of pressure, it's common to use kilopascals (kPa) for more convenient measurements since 1 kPa = 1000 Pa. In the United States, pressure is often expressed in pounds per square inch (psi), and another common unit is the atmosphere (atm), which is defined as the average sea level air pressure and is approximately equal to 14.7 psi or 101.325 kPa. These conversions are pivotal in comparing pressure readings obtained from different measurement units.