ONICON FB-3500 Series - Manual (Page 11)

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FB-3500 Bi-Directional Insertion Electromagnetic Flow Meter Manual 05/14 - 0718-3
Page 11
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 maximized on both sides of
the meter location.
!
i
!
• Acceptable to install in vertical pipe
• Position meter anywhere in upper 240°
for horizontal pipe
CLEARANCE
REQUIRED FOR
INSTALLATION
Typically 30” - 40”
depending on pipe size
and height of valve
assembly.
50%
Upstream
50%
Downstream
3.1.2 Insufficient Straight Run Site Selection Guidelines
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.
How To Determine The Available Straight Pipe Diameters:
For each application, locate the longest straight, unobstructed section of pipe (no bends, tees, valves,
other insertion probes, size transitions).
The longest straight pipe run in inches divided by nominal pipe size in inches equals
“diameters of straight pipe.”
For closed loop applications, consider both the supply and return lines as possible locations.