Series | Chapter 1 Introduction |
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Flow Velocity Range
To ensure
The measurable range is defined by the minimum and maximum velocity using the following table.
| Gas | Liquid |
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| 25 ft/s |
| 3 | |
Vmin | ρ | 1 ft/s | ||
English ρ (lb/ft ) | ||||
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Vmax | 300 ft/s | 30 ft/s |
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| 37 m/s |
| 3 | |
Vmin | ρ | 0.3 m/s | ||
Metric ρ (kg/m ) | ||||
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Vmax | 91 m/s | 9.1 m/s |
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The pressure drop for series 241 insertion meters is negligible. The pressure drop for series 240
ΔP = .00024 ρ V2 | English units (ΔP in psi, ρ in lb/ft3, V in ft/sec) |
ΔP = .000011 ρ V2 | Metric units (ΔP in bar, ρ in kg/m3, V in m/sec) |
The linear range is defined by the Reynolds number. The Reynolds number is the ratio of the inertial forces to the viscous forces in a flowing fluid and is defined as:
ρ V D
Re =
Where | ∝ |
Re = Reynolds Number
ρ= mass density of the fluid being measured
V | = | velocity of the fluid being measured |
D | = | internal diameter of the flow channel |
∝= viscosity of the fluid being measured
The Strouhal number is the other dimensionless number that quantifies the vortex phenomenon. The Strouhal number is defined as:
f d
St =
Where | V |
St = Strouhal Number
f= frequency of vortex shedding
d = shedder bar width
V = fluid velocity
