Baseline Systems BaseStation 3200 - Manual (Page 68)

BaseStation 3200 Advanced Irrigation Controller Manual
• Design Flow GPM – This field is the flow rating for the mainline in
gallons per minute (GPM). This flow is likely different from the design
flow of the POC/flow device. When a mainline has multiple POCs of
different capacity, the controller uses the constrained design flow to
determine the actual available flow for watering.
For example, consider the following design flows:
Flow Device #1 = 50 GPM
Flow Device #2 = 75 GPM
Mainline #1 = 100 GPM
In the example, the controller would use 100 GPM for managing zone concurrency unless flow device #2 was
shut off (over budget). In this case, the controller would use 50 GPM.
• Pipe Fill Time – This field represents the time that it takes to fill the pipe and achieve a steady flow rate after a
valve change. The default value is 2 minutes, but you can set it to any value between 1 and 30 minutes. Zone
changes are made at the top of the minute, and the zone is considered stable after the pipe fill time. One
minute after the pipe fill time, a valid flow is calculated (over the last minute interval).
• Limit by Flow – When the Limit by Flow field is set to Y (yes) the controller will use the design flow of the
individual zones (or learned flow) and will turn on zones that are waiting to water until their design flow is
equal or less than the available flow on the mainline. For example, with 100 GPM available, the system can run
three zones at 30 GPM and a fourth at 10 GPM at one time – later there may be two zones at 30 GPM and one
at 20 GPM (the system cannot always hit 100 GPM exactly).
• Flow Variance Settings
 High Alarm – You can set the high variance limit to Off or to any value between 1% and 100%. During
normal program watering, the controller compares the sum of the design flow (or learned flow) from all
running zones against the measured flow of the flow device (or the sum of all flow devices supplying
water to the mainline). The measured flow may be higher or lower than the expected flow. When the
ratio becomes greater than the variance, then an alarm is generated. For example, if the expected flow is
50 GPM, and the High Alarm variance is 10%, then the acceptable flow range is up to 55 GPM (10% of 50
GPM is 5 GPM).
 High Shutdown – Set this field to Y (yes) to have the system shut down when the high variance exceeds
the limits. A high alarm prompts the system to determine the zone (or set of zones) that is causing the
high flow variance. The currently running zones are marked as “suspects” and are shut off. The program
continues to water with another set of zones and one of the suspect zones. If the variance is within limits,
the zone will be marked as good and watering will continue. If the variance is out of limit, then the zone
will be marked as a failure and shut down. This method allows watering to continue almost without
interruption, while isolating the faulty zone or zones.
 Low Alarm – You can set the low variance limit to Off or from 1% to 100%. During normal program
watering, the controller compares the sum of the design flow (or learned flow) from all running zones
against the measured flow of the flow device (or the sum of all flow devices supplying water to the
mainline). The measured flow may be higher or lower than the expected flow. When the ratio becomes
greater than the variance, then an alarm is generated. For example, if the expected flow is 50 GPM, and
the Low Alarm variance is 10%, then the acceptable flow range is down to 45 GPM (10% of 50 GPM is 5
GPM).
 Low Shutdown – Set this field to Y (yes) to have the system shut down when the low variance exceeds the
limits. A low alarm prompts the system to determine the zone (or set of zones) that is causing the low
flow variance. The currently running zones are marked as “suspects” and are shut off. The program
continues to water with another set of zones and one of the suspect zones. If the variance is within limits,
Page 60