Programming instructions

Designer’s Guide 29
Calsense
• Maximum flow rate (in gpm) for the system
• Minimum flow rate (in gpm) for the system
• Permissible pressure loss through the flow meter
The maximum flow rate is the full-scale reading of a Flow Meter, and must not be exceeded by the flow
rate of any station in an irrigation system. The minimum flow rate is the lowest flow rate at which a Flow
Meter will measure flow. If the flow rate of a station does not exceed this minimum, the flow reading for
the station will be inconsistent and may result in a no-flow alert whenever the station irrigates.
To determine the correct Flow Meter size when designing an irrigation system, first determine the
station with the highest flow rate on the system. Next determine the station with the lowest flow rate
on the system. Then make sure that both flow rates are within the operating range of the selected Flow
Meter size in the table below. For systems with a large mainline, you may consider using multiple Flow
Meters configured as a bypass manifold to read both high and low flowing valves. See Bypass Manifold
on page 32 for more information.
Operation
The Flow Meter consists of an impeller and a sensing device which measures the flow in gallons per
minute (GPM). As irrigation progresses, the controller acquires an expected flow rate for each station.
By comparing a station’s actual flow rate to this expected flow rate, a broken head or riser will
immediately trigger a high flow, causing the affected station to shut off and the controller to turn on the
next station. This also generates an alert which is displayed on the station’s programming screen, in the
Model
Min Flow (0.5
fps)
Recommended Range
Max Flow (15
fps)
PSI Loss @
gpm
Min flow (1
fps)
Max Flow (15
fps)
FM-1B
2 gpm 3 gpm 50 gpm 50 gpm
0.5 psi @ 20
gpm
FM-1.25B
3 gpm 5 gpm 81 gpm 81 gpm
0.5 psi @ 45
gpm
FM-1.5B
4 gpm 7 gpm 106 gpm 212 gpm
0.5 psi @ 45
gpm
Model
Min Flow (0.5
fps)
Recommended Range
Max Flow (30
fps)
PSI Loss @
gpm
Min flow (1
fps)
Max Flow (15
fps)
FM-1.5
4 gpm 7 gpm 106 gpm 212 gpm
0.5 psi @ 60
gpm
FM-2
6 gpm 11 gpm 166 gpm 333 gpm
0.5 psi @ 100
gpm
FM-2B
6 gpm 11 gpm 166 gpm 333 gpm
0.5 psi @ 100
gpm
FM-3
12 gpm 24 gpm 363 gpm 727 gpm
0.5 psi @ 320
gpm
Model
Min Flow (0.5
fps)
Recommended Range
Max Flow (15
fps)
PSI Loss @
gpm
Min flow (1
fps)
Max Flow (15
fps)
FMBX
0.5 fps 1 fps 15 fps 30 fps n/a
Table 4: Recommend Flow Meter Operating Ranges