The industry's most authoritative handbook on flow measurement provides a road map to the field of flow measurement. This best-seller discusses strategies for problem solving and puts the whole array of types of flowmeters at the reader's disposal. The text includes laminar flow elements, critical flowmeters, statistics for measurement, laboratory primary standards, and uncertainty in flow measurement. Emphasis is placed on the importance of accuracy in measurements and ways of ensuring accuracy and avoiding equipment damage through correct forecast of operating conditions, flowmeter selection, installation, calibration, and maintenance. Fundamental considerations such as mixed-phase flow, piping effects, and flow conditioning are examined at length. The problem of attaining a meaningful flow signal through linearization, compensation, and totalization is discussed. Join the thousands of engineers, technicians, managers, and salespeople that have found this reference text an invaluable resource.
TABLE OF CONTENTS Chapter 16 - Target Flowmeters
Versatility and low installation cost make the target flowmeter a viable candidate
for many difficult flow measurement applications. Full bore, in-line meters are
available in sizes from 1/2 to 6 inches. Insertion versions for larger line sizes are
also available. Target flowmeters are used on liquids, gases, vapors, dirty fluids,
light slurries, and high viscosity fluids, particularly where fluid characteristics
preclude the use of flowmeters with pressure taps or moving parts. Process temperatures
vary from cryogenic to low temperature steam.
Operating Principle
Whenever there is flow past an obstacle in a pipe, a force, commonly referred There are two primary contributors to drag. One results from the force generated | Advantages:
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The obstacle or target typically used in practice is a circular disc mounted concentrically
in a pipe. The idealized flow past such a target is shown in Figure 16-1.
The upstream face sees a relatively high pressure since the forward motion of a
large percentage of the fluid is abruptly stopped before turning and traveling
around the target. As the fluid passes through the annulus around the target, it sees
an increase in velocity and, as a result, a decrease in pressure. At the downstream
edge of the plate, this high velocity, low pressure flow separates from the target
surface, setting up turbulence downstream of the target. This results in a relatively
low pressure region near the downstream face.
