Sierra InnovaMass 240i Series, Instruction Manual, Page: 10 / 115

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laminar and transitional flow in real-time as they would occur inside the pipe or duct (See Figure
C). This results in increased accuracy, particularly at low flow rates of Reynolds Number of 5000
and below.
Figure C. Ratio of Laminar, Transitional and Turbulent flow regimes and Reynolds number
(Source: Richard Miller, Flow Measurement Engineering Handbook.)
Flow Velocity Range
To ensure trouble-free operation, vortex flow meters must be correctly sized so that the flow
velocity range through the meter lies within the measurable velocity range (with acceptable
pressure drop) and the linear range.
The measurable range is defined by the minimum and maximum velocity using the following
table.
Gas Liquid
Vmin
√
25
⍴
𝑓𝑡/𝑠
1 ft/s
English

(lb/ft
3
)
Vmax 300 ft/s 30 ft/s
Vmin
√
37
⍴
𝑚/𝑠
0.3 m/s
Metric

(kg/m
3
)
Vmax 91 m/s 9.1 m/s
Figure D. Flow Velocity Range
The pressure drop for series 241i insertion meters is negligible. The pressure drop for 240i Series
inline meters is defined as:

P = .00024

V
2
English units (

P in psi,

in lb/ft
3
, V in ft/sec)

P = .000011

V
2
Metric units (

P in bar,

in kg/m
3
, V in m/sec)