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Published in Samuel C. Sugarman, HVAC Fundamentals, 2020
manometer: (Instrumentation) An instrument for measuring air or water pressures. Essentially, a U-tube partly filled with a liquid, usually water, mercury or a light oil. The pressure exerted on the liquid is indicated by the liquid displaced. A manometer can be used as a differential pressure gauge. The manometer is used in the HVAC industry for measuring air pressure. Other pressure measuring instruments may be checked for calibration against a properly set up and accurately read manometer. Both analog and digital manometers are used. Analog types include inclined manometer, inclined vertical manometer, and U-tube manometer. The digital type is an electronic manometer and micro-manometer combination. Analog manometers contain no mechanical linkage and don’t need calibration. The digital manometer, on the other hand, needs periodic calibration as recommended by the manufacturer or certified calibration agency. The electronic manometers are battery-powered which need to be checked before each use.
Measuring Ventilation Flow Rates
Published in William Popendorf, Industrial Hygiene Control of Airborne Chemical Hazards, 2019
A manometer is a common tool with which to measure pressure differences in ventilation, including duct pressure, VP, or total pressure. A U-tube manometer is a vertical, U-shaped, transparent tube containing a liquid such as water, oil, or mercury. In ventilation, the liquid is always water or measured as if it were water. In use, a difference between the pressures [ΔP] applied to each leg of the U-tube will cause a difference in the height or head of the water within each leg of the manometer (abbreviated as Δh). The height difference can be measured by a scale attached to the manometer such as those shown in Figure 12.2. The units of measured differences in the height of water are abbreviated ″wg for inches of water gauge or mmwg for millimeters of water gauge.a The Δh depicted within each manometer within Figure 12.2 is 3.2 ″wg.
Instruments and Instrument Terminology
Published in Samuel C. Sugarman, Testing and Balancing HVAC Air and Water Systems, 2020
The manometer is the standard of the industry for measuring air pressure. Other pressure measuring instruments may be checked for calibration against a properly set up and accurately read manometer. Both analog and digital manometers are used. Analog types include the inclined manometer, the inclined vertical manometer, and the U-tube manometer. The digital type is an electronic manometer and micromanometer combination. Analog manometers contain no mechanical linkage and don’t need calibration. The digital manometer, on the other hand, needs periodic calibration as recommended by the manufacturer or certified calibration agency, or as needed. The electronic manometers run on batteries, which need to be checked before each use.
Effect of V cut in perforated twisted tape insert on heat transfer and fluid flow behavior of tube flow: An experimental study
Published in Experimental Heat Transfer, 2019
Bipin Kumar, Manoj Kumar, Anil Kumar Patil, Siddharth Jain
A set of 11 thermocouples are fixed over the tube wall to measure the surface temperature. Thermocouples are placed on the outer surface of tube by keeping them 0.090 m apart with each other. Since the tube is made of copper having thickness 0.001 m, therefore, it is reasonable to neglect the effect of tube thickness. A set of three thermocouples with angular shift of 120° are inserted in the fluid stream at exit cross-section and one thermocouple at the inlet of the tube to measure the fluid temperatures. The exit temperatures of air recorded by means of three thermocouples are used to determine the average exit temperature. The location of thermocouples at the exit to the test section is shown in Figure3. All the thermocouples are connected with a 24-channel data logger to record the temperatures under steady-state conditions. A U tube manometer with water as manometric fluid is used to measure the pressure drop across the orifice plate which is eventually reduced into mass flow rate of fluid through the system. The digital micromanometer is used to measure the pressure difference across the test section.