ONICON F-1100 Series - Manual (Page 11)

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Turbine Flow Meter Manual 05/14 - 0721-3 / 13518
Page 11
Series FB-1200 Dual Turbine Flow Meters
Bi-Directional Flow Applications
GENERAL PRACTICES
1. For best results, install the flow meter in a straight run of pipe,
free of bends, tees, valves, transitions, and obstructions for a
distance of at leas 10 pipe diameters on each side of the flow
meter.
2. Longer straight runs may be required in applications where
the meter is placed downstream from devices which cause
unusual flow profile disruption or swirl, for example,
modulating valves or two elbows in close proximity and out of
plane, etc.
3. If there is not sufficient straight run, allow 50% of the run up
stream and 50% of the run downstream. If the total length of
straight run is less than 70% of the recommended distance,
performance may degrade and
considerations should be given to
changing to the F-3000 Series Inline
Electromagnetic flow meter.
FLOW DIRECTION
SWITCH CLOSED
Minimum upstream
straight run distance
10 pipe diameters from any
valve, elbow, fitting, etc.
Minimum downstream
straight run distance
10 pipe diameters to any
valve, elbow, fitting, etc.
FLOW DIRECTION
SWITCH OPEN
Insufficient Straight Run Guidelines for Bi-directional Flow Applications
If there is insufficient available straight run, allow 50% of the run upstream and 50% of the run
downstream. If the total length of straight run is less than 20 diameters, performance may degrade
and consideration should be given to changing to the F-3100 or F-3200 In-line Electromagnetic
Flow Meters.
Some installations may work better with straight run optimized for flow in one direction. For
example, with flow meters installed in the bypass line between de-coupled constant volume
primary and variable secondary loops, it may be more important to accurately measure positive
flow (from supply to return.) Negative flow measurements (from return to supply) are generally
less critical, and it may be enough just to know that any negative flow is present. In this scenario,
maximizing straight run for positive flow might be a preferred strategy.
IMPORTANT NOTE
Always use the maximum available straight run. When more than the minimum required
straight run is available, place the meter such that the excess straight run is upstream of the
meter location.
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