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<< Click to Display Table of Contents >> Irrigation Tree |
  
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<< Click to Display Table of Contents >> Irrigation Tree |
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The Irrigation tree is the main way of creating, editing, and reviewing how the system irrigation interacts with one another. Two columns that are used for each element in the tree can be edited in place. The name is used as reference in reports. The GPM column has different meanings for each type of element in the tree. The tree is comprised of three hierarchical elements: the zone, the node, and the station. When selecting a zone or node, the ISC grid will be populated with the stations associated to that zone or node, unless the lock grid button is enabled (see Lock Grid).
The zone is the top-most element in the tree. It is a metaphor that represents a main line and as such, provides as a source which all elements under it must get water from. A zone may have any number of nodes representing branches in the main line. The GPM represents the maximum amount of water the main source can provide each minute which is typically determined by the pipe’s dimensions. Each zone has a water window within which all the scheduled irrigation events are expected to complete.
In order to protect pumps and pipes, a zone has an optional GPM step property which allows a zone to consider ramping up water usage over a set number of minutes to help prevent water hammer. The value entered represents the number of minutes to ramp up, as well as the GPM to use for each of those minutes by dividing the GPM by the number of minutes. For example, a zone with 200 GPM with a GPM step of 4 will take 4 minutes to slowly ramp up to 200 GPM by adding 50 GPM each minute of its ramp up.
The node is the middle element in the tree. It represents branches of pipe between the source and the stations. A node may have any number of stations and any number of nodes. Its GPM also represents the maximum amount of water it can provide each minute. However, there are constraints on this value. Each node’s GPM must be equal to or less than the GPM value of its direct parent (whether that parent is a zone or a node).
The station is the last element in the tree. A station must be a child of a node and may not have any children of its own. Its GPM is the rate of water it is expected to use while activated. This can be the design GPM of the model. It can also be the nominal value calculated via the Learn Nominals operation. This value is used in scheduling to determine how much water a station is using during the schedule recalculation operation.