Fluke 922 Fluke Low Pressure Differential Meters - HVAC Pressure Applications - Page 1

HVAC pressure applications with the Fluke 922 Application Note For contractors troubleshooting pressure, a lot depends on system peculiarities. Are the installation instructions with the equipment? Is the start-up performance report with them? Is the TAB (test and balance) report available? Do you understand the control system? More often than not, it seems, you can only answer yes to the last question. You rely on your experience, knowledge, and tools to check the fundamentals. And for that much, at least, Fluke can help. Using the Fluke 922 low pressure differential meter in a duct traverse. Pressure measurement Pressure is measured in several different scales. Pounds per square inch (psi), inches of water column (in. wc), inches of mercury column (in. hg), and millionths of a meter of mercury column (microns) are the most typical in HVAC work. Bourdon gauges are the traditional choice for higher pressure readings in psi. Finer precision measurements use mercury column scales. And for the most precise measurements-and most low pressure measurements in HVAC-inches water column is the standard. The following chart compares these common pressure scales and their precision. Atmospheric Pressure 14.696 psia 29.921 " hg 406.8" wc 1 psi 1 psi 2.036" hg 27.68" wc 1" hg 0.019 psi 1" hg 0.535" wc 1" wc 0.0361 psi 0.0736" hg 1" wc Of the many different low pressure measuring instruments used over the years, electronic manometers/micromanometers (very low pressure gauges) now offer durability, precision, accuracy, and the significant time saving convenience of fully automatic calculations as well as minimum-maximum-average and memory functions. From the Fluke Digital Library @ www.fluke.com/library