Pump

A pump imparts energy to a fluid thereby raising its hydraulic head. The relationship describing the head imparted to a fluid as a function of its flow rate through the pump is termed the pump characteristic curve (see Curve section help for more information). Pumps are modeled as Nodes in InfoWater Pro.

Because pumps impart energy to a water system, they may be analyzed during an Extended Period Simulation (EPS)  for Energy Management.

This page contains the following topics:

• Type of Pumps
  • Constant Power Input
  • Design Point Curve
  • Exponential 3-Point Curve
  • Multi-Point Curve
• Create a Pump
• Edit a Pump
• Edit the data for a group of Pumps
• Delete a Pump
• Analyze a VSP Pump
  • Pump Affinity Laws
  • Assigning a Known Speed Pattern to a Pump
  • Using a Explicit VSP/FPP Analysis to Create a Speed Pattern

Type of Pumps

Selecting the Pump Type will impact the hydraulic information necessary to be entered for the pump in the Modeling section from the Model Explorer - Attribute Tab window when the pump is the active element in the Model Explorer. 

Four different types of pumps that you are able to input into InfoWater Pro.

Constant Power Input

The characteristic curve is unknown and constant power output is used.  The power supplied by the pump in horsepower (kiloWatt). Assumes that the pump supplies the same amount of energy no matter what the flow is.  The Head h_G at any flow q is calculated via this formula h_G - 8.81 *Hp / q  where h_G is the head gain imparted by the pump in ft, Hp is the pump useful horsepower, and q is the flow through the pump in cfs. These curves should only be used for steady-state preliminary design studies when the specific operating characteristics of the pump are not known. Via the Modeling section under the Model Explorer - Attribute Tab window, enter the following:

• Elevation - The elevation of the pump, ft. (m)
• Diameter - The diameter of the pump, in. (mm)
• Constant Power - The power rating in Hp (kW) of the pump in the field.

Note:

Constant power pumps will allow flow reversal and should not be used under a zero flow condition (no flow passing through the pump).

Design Point Curve

A standard pump curve with no extended flow range, where the cutoff head is 133 percent of the design head and the maximum flow at zero head is set at twice the design flow.  Via the Modeling section under the Model Explorer - Attribute Tab window, enter the following:

• Elevation - The elevation of the pump, ft. (m)
• Diameter - The diameter of the pump, in. (mm)
• Design Head - The design operating head, ft (m)
• Design Flow - The design flow, in the model default flow units, such as gpm (L/s)

Exponential 3-Point Curve

A three-point pump curve. A three-point pump curve is defined by three operating data points: The Shutoff Head (flow and head at low or zero flow condition), a Design Flow point (flow and head at desired operating point), and a High Flow point (flow and head at maximum flow). InfoWater Pro will fit a continuous function of the form: h_g = h₀ - a*q^b  Where: h_g is the head gain imparted by the pump in ft, q is the flow through the pump in your default flow units, h_o is the shutoff head in feet, a is a resistance coefficient, and b is a flow exponent. By supplying InfoWater Pro with the shutoff head h_o and two other points [(h₁, q₁ ) the Design Head and Flow and (h₂, q₂ ) the High Head and Flow] on the pump curve, the program is able to estimate values for a and b from the following equations and develop a full pump curve:

  Via the Modeling option under the Model Explorer - Attribute Tab window, enter the following:

• Elevation - The elevation of the pump, ft. (m)
• Diameter - The diameter of the pump, in. (mm)
• Shutoff head -The shutoff head at zero flow, ft (m).
• Design head - The design operating head, ft (m)
• Design flow - The design flow, in the model default flow units, such as gpm (L/s)
• High Head - The head at the upper end of normal operating flow range, ft (m).
• High Flow - The flow at the upper end of normal operating flow range, in the model default flow units, such as gpm (L/s).

Multi-Point Curve

A curve representing the head vs. flow relationship.  The curve may contain any number of data points, but the more points the better the curve will be represented.  When a pump selected is the active element in the Model Explorer - Attribute Tab window to quickly open the Curve Editor, you can double click on the word "Curve"   in the Modeling section to quickly open the Curve Editor. Then select the Curve option drop-down box and choose the representative multi-point curve.  Refer to the Curves section of the help file to learn more about a Head vs. Flow curve. The Head vs. Flow curve will contain flow points with the X values in your default flow units such as gpm (L/s) and head values in ft (m).  NOTE: The pump curve data is linearly interpolated between the points entered, so the more points added, the curve will better represent the actual shape of the pump curve. Via the Modeling option under the Model Explorer - Attribute Tab window, enter the following:

• Elevation - The elevation of the pump, ft. (m)
• Diameter - The diameter of the pump, in. (mm)
• Curve - Specify the multi-point curve to be used by the pump. The curve can be selected from the available curve list using the drop-down menu.

Create a Pump

To create a pump, do the following:

Click on the InfoWater Pro Ribbon in the Edit Group using the →   Insert Element Command dropbox   .   Select the Insert Pump icon  from the  →   Insert Element Command dropbox .

Note:

When the Insert Pump command is the active command it will be highlighted in Blue as shown: .

Once the command is initiated, select the location of the new node by left mouse clicking anywhere on the map display. Suggest a new ID and/or a description on the Pump Identification dialog box and click OK to accept the ID and create the new Pump. The Pump should visually appear at the specified location. If the insert location is near an existing model pipe the software will prompt to insert the pump into that pipe. If you wish to split the pipe, the Pump Identification dialog box for the new pump and the new pipe will appear in a pop-up window.

Note:

You can also use the Digitize Network icon from the →   Insert Element Command dropbox   to create a pipe and node network on the fly.  Once digitized, you are to add relevant modeling data in the Model Explorer - Attribute Tab window or via the DB Editor.

Edit a Pump

Graphic Selection - To select a Pump for data edit do one of the following: Choose the Select icon  from the Model Explorer - Attribute Tab window and click on the specific Pump or select the InfoWater Pro Ribbon in the Edit Group using the →   Select icon   to select the pump.

If a Pump has been prior selected and is a part of the Browse history, it can be re-selected by choosing it from the Browse-History section of the Model Explorer - Attribute Tab window.

Data Edit - To edit the data related to a junction, first select the junction using the tools above. Once selected, edit Junction related data by adding/modifying the fields in the Model Explorer - Attribute Tab window.  Additionally modifications may be done by editing the DB Tables that may be accessed from the InfoWater Pro Ribbon in the Edit Group using the  →   DB Editor   icon  .

Move Node  - To Move the node location graphically do one of the following: From the  InfoWater Pro Ribbon in the Edit Group using the →   Edit Command dropbox icon  select the Move Node command  from the drop-down menu. Left click on the mouse and hold the left click down on the junction to select it. With the junction highlighted move the node to the desired position while keeping the left click mouse button depressed. Once in the desired location, release the left mouse button and the node location will be updated to the new location. 

Note:

When the Move Node command in the InfoWater Pro Ribbon in the Edit Group → Edit Command dropbox is the active command it will be highlighted in Blue as shown:  . If you have not enabled "Auto Length Calculation" checkbox   under the InfoWater Pro Ribbon in the Project Group using the Preferences icon   and the Operations tab, all pipes connected to a node moved will not have their lengths automatically changed.

Edit the data for a group of Pumps

Group edits can be made by either creating a domain or by creating a selection.

Using the Domain Manager - Create a domain selecting the specific junctions that you want to edit. Refer to the section on Domain Manager for details on the domain creation process. Once the domain has been created, choose the InfoWater Pro Ribbon in the Edit Group using the →   DB Editor  icon . Depending on the data you want to edit choose the appropriate table type from among the different database tables. Choose as the Data Scope and click OK.

Using the User Selection - Select choose the InfoWater Pro Ribbon in the Edit Group using the →   DB Editor  icon  .  Depending on the data you want to edit choose the appropriate table type from among the different database tables. Choose as the Data Scope and choose the User Selection  command. This places the software in User Selection Mode.  In InfoWater Pro, the Selected elements will be in a  cyan  color.  Once all of the desired junctions are selected, right click and choose Enter to access the DB Tables for the selected junctions. Once the specific tables have been opened with the desired scope, enter data one cell at a time or Block Edit data to make changes in bulk to multiple cells.

Note:

Group Editing  for certain specific features may also be done by choosing the Group Editing icon   or the Edit Domain icon  under the InfoWater Pro Ribbon in the Edit Group . Refer to the sections on Group Editing and Edit Domain to learn more.

Delete a Pump

To delete a Pump, select the Delete Node option   in the InfoWater Pro Ribbon in the Edit Group →   Edit Command dropbox.  Select the node element to be deleted and InfoWater Pro prompts you you to confirm deletion (if the Delete Confirmation checkbox   is checked in the Operation Settings tab in the Preferences settings  . The active selected pump in the Model Explorer - Attribute Tab window may also be deleted by selecting the Delete icon   with the InfoWater Pro prompt to confirm element deletion.  

Note:

All pipes attached to the Node being deleted will also be deleted if the Auto Pipe Delete checkbox   is checked in the Operation Settings tab in the Preferences settings .  The Node and associated pipes are deleted and saved in the InfoWater Pro recycle bin and can be recalled from the database using the Model Explorer - Command Center Tab under Utilities - > Recall (Node or Pipe) command. However, if Auto Database Packing   is checked (Operation Settings tab in the Preferences settings ), then any element deleted is permanently deleted from the database and cannot be recalled. Deleted elements can be recalled until the Pack and then Clean commands (found in the Model Explorer - Command Center Tab under Utilities → Database  menu list)are completed which removes deleted element ID's from the database.

Analyze a VSP Pump

In addition to the normal simple controls and rule based controls that can be applied to a pump, a pump's operation can also be described by assigning it a time pattern of relative speed settings.  For variable speed pumps, the pump curve shifts as the speed changes. Most users today make use of the Implicit Variable Speed Pump control  to specify a control type in order to change the speed of the pump automatically by the software as needed. The Implicit Variable Speed Pump Control automatically calculates pump speeds over time during extended period simulation (EPS) runs. It maintains user-specified fixed or time-varying (pattern-based) heads at nodes anywhere in the system or fixed or time-varying pump discharge flows. This allows you to accurately mimic the actual operational behavior of the variable speed pump. See the separate help page for Implicit Variable Speed Control settings for more detail.

To assign an Implicit Variable Speed Control to a pump, choose the Select icon   from the Model Explorer - Attribute Tab window and click on the specific Pump or select the InfoWater Pro Ribbon in the Edit Group using the →   Select icon   to select the pump. Choose the Variable Speed Control command from the Tools icon   on the Model Explorer - Attribute Tab window or select the Variable Speed Pump Control Icon  in the Model Explorer - Attribute Tab window .  Variable speed pumps can be considered by specifying that their speed setting be changed under these same types of conditions.  By definition, the original full speed pump curve supplied to the program has a relative speed setting of 1. If the pump speed doubles, then the relative setting would be 2; if run at half speed, the relative setting is 0.5 and so on.  Pump affinity laws are used to determine the shape of a pump curve at different speeds. Changing the pump speed shifts the position and shape of the pump curve. Most real world pumps are not designed to run at speeds greater than 100% of full speed so use caution when allowing speeds greater than 100% of full speed in the Variable Speed Pump Control.

Pump Affinity Laws

For variable speed pumps, the pump curve shifts as the speed changes. The relationships between flow (q) and head (h)  of a pump curve at speeds n₁ and n₂ are:

Assigning a Known Speed Pattern to a Pump

To assign a known speed pattern to a pump, choose the Select icon   from the Model Explorer - Attribute Tab window and click on the specific Pump or select the InfoWater Pro Ribbon in the Edit Group using the →   Select icon   to select the pump.  Choose the Control command from the Tools icon  on the Model Explorer - Attribute Tab window or select the Control Icon   in the Model Explorer - Attribute Tab window .  When the Pump Control dialog box appears, select the Pattern radial button  under the Method section and from the Pattern ID drop-down menu, select the pattern that describes the pump speed settings.  Such a pattern might resemble the following with the pump speed varying from 50 to 100% of full speed. 100% speed is represented by 1.0 and 50% speed is represented as 0.50 in the pattern:  (Notice how the speed setting changes to resemble throttling throughout the day.)

Using a Explicit VSP/FPP Analysis to Create a Speed Pattern

In many instances, you will not know how the speed of the pump changes over time.  Because of this variable, InfoWater Pro allows for the creation of this pattern through the use of a VSP/FPP Analysis which is done through the Standard tab of the Run Manager. 

Additionally simple controls and rule based controls may also be applied to pumps to specify pump operations.