TABLE
1.
FLOWMETER SELECTION GUIDE |
Flowmeter
element |
Recommended
Service |
Rangeability |
Pressure
Loss |
Typical
Accuracy,
percent |
Required
Upstream
pipe,
diameters |
Viscosity
effect |
Relative
Cost |
| Orifice |
Clean,
dirty
liquids; some
slurries |
4 to 1 |
Medium |
±2
to ±4
of full
scale |
10
to 30 |
High |
Low |
| Wedge |
Slurries
and
Viscous liquids |
3
to 1 |
Low
to
medium |
±0.5
to ±2
of full scale |
10
to 30 |
Low |
High |
| Venturi
tube |
Clean,
dirty
and viscous
liquids; some
slurries |
4
to 1 |
Low |
±1
of full
scale |
5
to 20 |
High |
Medium |
| Flow
nozzle |
Clean
and
dirty liquids |
4
to 1 |
Medium |
±1
to ±2
of full scale |
10
to 30 |
High |
Medium |
| Pitot
tube |
Clean
liquids |
3
to 1 |
Very
low |
±3
to ±5
of full scale |
20
to 30 |
Low |
Low |
| Elbow
meter |
Clean,
dirty
liquids; some
slurries |
3
to 1 |
Very
low |
±5
to ±10
of full scale |
30 |
Low |
Low |
| Target
meter |
Clean,
dirty
viscous
liquids; some
slurries |
10
to 1 |
Medium |
±1
to ±5
of full scale |
10
to 30 |
Medium |
Medium |
| Variable
area |
Clean,
dirty
viscous liquids |
10
to 1 |
Medium |
±1
to ±10
of full scale |
None |
Medium |
Low |
Positive
Displacement |
Clean,
viscous
liquids |
10
to 1 |
High |
±0.5
of
rate |
None |
High |
Medium |
| Turbine |
Clean,
viscous
liquids |
20
to 1 |
High |
±0.25
of
rate |
5
to 10 |
High |
High |
| Vortex |
CLean,
dirty
liquids |
10
to 1 |
Medium |
±1
of rate |
10
to 20 |
Medium |
High |
| Electromagnetic |
Clean,
dirty
viscous con-
ductive liquids
and slurries |
40
to 1 |
None |
±0.5
of
rate |
5 |
None |
High |
Ultrasonic
(Doppler) |
Dirty,
viscous
liquids and
slurries |
10 to 1 |
None |
±5
of full
scale |
5
to 30 |
None |
High |
Ultrasonic
(Time-of-travel) |
Clean,
viscous
liquids |
20 to 1 |
None |
±1
to ±5
of full scale |
5
to 30 |
None |
High |
Mass
(Coriolis) |
Clean,
dirty
viscous
liquids; some
slurries |
10
to 1 |
Low |
±0.4
of
rate |
None |
None |
High |
Mass
(Thermal) |
Clean,
dirty
viscous
liquids; some
slurries |
10
to 1 |
Low |
±1
of full
scale |
None |
None |
High |
Weir
(V-notch) |
Clean,
dirty
liquids |
100
to 1 |
Very
low |
±2
to ±5
of full scale |
None |
Very
Low |
Medium |
Flume
(Parshall) |
Clean,
dirty
liquids |
50
to 1 |
Very
low |
±2
to ±5
of full scale |
None |
Very
low |
Medium |
