Volume I - Section VII - Glossary of Terms 
Page VII - 3 
manometers commonly used to measure air pressure are the inclined manometer, the inclined- 
vertical manometer, the U-tube manometer, and the micromanometer. 
Meniscus: the curved surface of the liquid column in a manometer. In manometers that measure 
air pressure, the liquid is either water or a light oil. In manometers that measure water pressure, 
the liquid is mercury. 
Metabolic Rate: in comparative physiology, the rate of an animal’s energy consumption, that is, 
the rate at which it converts chemical energy to heat and external work. 
Micromanometer: an instrument used to measure very low pressure, accurate down to plus or 
minus one-thousandth (0.001) inch of water gage. 
Operating load point: the actual system operating capacity when an instrument reading is taken. 
Parallax: a false reading that occurs when the eye of the reader is not exactly perpendicular to the 
lines on an instrument scale. 
Pitot tube: a sensing device used to measure total pressure in a fluid stream, invented by a French 
physicist, Henri Pitot, in the 1700’s. The standard Pitot tube has a double tube construction with 
a 90-degree radius bend near the tip and measures both total and static pressures. 
Relative humidity: the ratio of the partial pressure of water vapor in moist air to the saturation 
vapor pressure at the same temperature. 
Sensible heat: the amount of heat required to raise the temperature of a solid. 
Sensitivity: a measure of the smallest incremental change to which an instrument can respond. 
Sheltered set: a set of instruments used only to check the calibration of field instruments. 
SCFM (standard cubic feed per minute): the volumetric rate of air flow at standard air conditions. 
Thermoneutral zone: a range of environmental temperatures within which the metabolic rate is 
independent of ambient temperature and is lower in range than any other ambient temperature. 
U-tube manometer: a manometer with a U-shaped glass or plastic tube partly filled with oil or 
tinted water. 
7.2 CFD Glossary 
Advection: the process by which a quantity of fluid is transferred from one point to another due 
