Reference Manual
00809-0100-4727, Rev EA
October 2010
Rosemount 8700 Series
3-4
MAGNETIC
FLOWMETER SIZING
Flowmeter Sizing
Because of its effect on flow velocity, sensor size is an important
consideration. It may be necessary to select a magnetic flowmeter that is
larger or smaller than the adjacent piping to ensure the fluid velocity is in the
specified measuring range of the sensor. Suggested guidelines and examples
for sizing normal velocities in different applications are listed in Table 3-2,
Table 3-3, and Table 3-4. Operation outside these guidelines may also give
acceptable performance.
To convert flow rate to velocity, use the appropriate factor listed in Table 3-2
and the following equation:
Table 3-2. Sizing Guidelines
Application
Velocity Range (ft/s)
Velocity Range (m/s)
Normal Service
2–20
0.6–6.1
Abrasive Slurries
3–10
0.9–3.1
Non-Abrasive Slurries
5–15
1.5–4.6
Example: SI Units
Magmeter Size: 100 mm
(factor from Table 3-3 = 492.0)
Normal Flow Rate: 800 L/min.
Example: English Units
Magmeter Size: 4-in.
(factor from Table 3-3 = 39.679)
Normal Flow Rate: 300 GPM
Velocity =
Flow Rate
Factor
Velocity =
Velocity = 1.7 m/s
800
(L/min.)
Velocity =
Velocity = 7.56 ft/s
300 (gpm)
39.679
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