by U.S. Dept. of Commerce, National Bureau of Standards in Gaithersburg, MD .
Written in English
|Series||NBS technical note -- 1302, NBS technical note -- 1302|
|Contributions||United States. National Bureau of Standards, George C. Marshall Space Flight Center|
|The Physical Object|
|Pagination||v, 86 p. :|
|Number of Pages||86|
Baldrige Performance Excellence Program; Manufacturing Extension Partnership (MEP) Metering of Fluids at High Velocities with Vortex Shedding Flowmeters. Published. March 1, Author(s) NIST Pub Series. Technical Note (NIST TN) Pub Type. NIST Pubs. Chemical engineering and processing and Flow metrology and rheology. Created Author: James D. Siegwarth. The hydrogen gas flow velocities in other ducts exceed the maximum for gas flow measurement by more than a factor of 3. The results presented here show from water flow tests that vortex shedding flow meters of the appropriate design can measure water flow to velocities in excess of 55 m/s, which is a Reynolds number of about 2 : J. D. Siegwarth. VORTEX SHEDDING FLOW METER PERFORMANCE AT HIGH FLOW VELOCITIES S. AUTHOR(S) J. D. Siegwarth 6. PERFORMING ORGANIZATION (If joint or other than NOS, sea instructions) 7. Contract/Grant No. H NATIONAL BUREAU OF STANDARDS DEPARTMENT OF COMMERCE 0. Type of Report & Period Covered WASHINGTON, D.C. Vortex shedding flowmeters detect and measure the velocity of liquid and gas vortices that are formed when the aerodynamics of a gas or liquid stream are disrupted.
Flow Damping adjustable between and seconds. Process Temperature Damping adjustable between and seconds (MTA Option Only). Response time Three vortex shedding cycles or ms, whichever is greater, maximum required to reach % of actual input with the minimum damping ( seconds). Turn-on time HART analogFile Size: 2MB. Vortex flow meters are a direct type of flow-measuring device with operating fundamentals based on the Von Karman Vortex Street principle. In this instrument, a bluff body or shedder bar is arranged at the center of flow path. When the fluid passes through it, disturbances in the flow called vortices are alternately formed on both sides of the shedder. Vortex flow meters operate under the vortex shedding principle, where an oscillating vortexes occur when a fluid such as water flow past a bluff (as opposed to streamlined) body. The frequency that the vortexes are shed depend on the size and shape of the body. If the volumetric flow rate through a vortex flow meter falls below the low-flow cutoff value, however, the flow meter’s signal goes completely to zero, indicating no flow at all. This idiosyncrasy makes vortex flow meters entirely unsuitable in applications where the desired flow measurement range extends all the way down to zero.
Vortex flow meters offer many advantages for flow measurement including easy installation without impulse lines, no moving parts to maintain or repair, less leak potential and a wide flow turndown range. Vortex meters also offer very low power consumption, allowing for use in remote areas. Additionally, Vortex meters are unique in that they can accommodate liquids, gasses, steam and corrosive applications. Vortex flow meters are also able to withstand high process . The VersaFlow Vortex Shedding flow meter detects the vortices that are created by a process medium going past a bluff body. The frequency of these vortices can be equated into flow velocity, which, in turn, is used to calculate volumetric flow rate. Little resistance to flow. Disadvantages of vortex shedding flowmeters: At low flows, pulses are not generated and the flowmeter can read low or even zero. Maximum flowrates are often quoted at velocities of 80 or m/s, which would give severe problems in steam systems, especially if the steam is wet and/or dirty. We have developed the ultrasonic vortex flow meter "ULTRA YEWFLO" specifically for liquid measurement. This flow meter detects the vortex shedding frequency that is proportional to the flowrate. The flow meter has a simple construction with no moving parts which means that it is not affected by clogging caused by slurry or rust inside the pipe.