Pump

To add a new pump, click the button  of Components toolbar and select the equipment type "Pump" (or use the corresponding item of "Insert - Component - Equipment" menu). Please note that the new component is added to the project tree after the currently selected element. Therefore, to add a new component after an existing one, select it in the project tree or in the graphic window and add the new component. If you need to add a new component to the beginning of a branch, select the branch in the project tree and add the new component.

The pump element is used to model the operation of centrifugal pumps with known characteristics on a pipeline system and to determine the pump operating point. Note that if the pump operating point is initially known (for example, the flow through the pump is controlled by a control valve and the pump head is known for this flowrate), then it is not necessary to specify the "Pump" element in this case (unless you plan to perform a waterhammer calculation). In this case, the pump can be modeled as a "Component with known change of pressure and/or temperature", for which the pump head can be specified manually. Or, if the pump is at the starting point of the piping system, you can simply specify the pressure at the pump outlet as the initial pressure in this system, without modeling the pump itself.

If the purpose of your calculation is to select a pump, then you do not need to specify the "Pump" element for this. Pump selection is performed in a different way - see below for more details .

After adding a pump, its characteristics will be displayed in the Object Properties Window:

• name - by default, the name of any piping component coincides with its type, but if necessary, the name can be changed in this field. When changing the hydraulic component type (when selecting different types of equipment), its name will also change, but only if it has not been previously changed to another manually. Specify the name that you would like to see for this element in reports with calculation results. To display the name of a pipeline element on the diagram, click the corresponding button to the right of its name;

• pump outlet diameters (inner and outer) - by default they are taken to be equal to the diameters of the pump inlet (i.e., diameter of the component before the pump). If necessary, they can be changed in these fields. The specified values of the new inner and outer diameters after the pump are applied to all components of the branch after this component until the end of the branch or until the next component with a diameter change (if there is one in this branch). Please note that when adding and deleting pumps, as well as when changing their new diameter value, the program will not only automatically adjust the values of the diameters of all the following components in this branch (up to the first element with a change in diameter if any), but will also change the values of the radii of the bends and elbows in this branch if they are equal to the standard value of 1.5*DN (for pipes with DN < 500mm) or 1*DN (for pipes with DN >= 500mm);

• quantity - this parameter is usually not used for pumps. It is used for other pipeline elements (for example, for valves) when modeling several identical elements. In this case, you can enter the number of these elements in this field and when calculating the hydraulic resistance on this element will be multiplied by the specified value. Since there are unlikely to be several identical pumps installed in series in one pipeline branch, this option is of no practical interest for it;

• pump data - clicking this button will open a window in which you must enter the pump characteristics. These include:

1. • control type/performance curve/manufacturer - these parameters are filled in "for reference", they are not required for calculations and preparation of reports with results;

   • pump head vs. flow rate curve is the main characteristic of the pump, which determines its operation on a given pipeline system. It must be specified for the pump;

   • pump NPSH vs. flow rate curve - this characteristic is required only if you plan to calculate the required NPSH at the pump operating point. Otherwise, it can be omitted;

   • range of operation limits - here you can specify the boundaries of the preferred working zone of the pump. If the calculation shows that the pump's working point is outside this zone, the program will show a corresponding warning. If the boundaries are not specified, this diagnostic will not be performed. The working zone boundaries are displayed as a blue rectangle on the graph;

   • pump impeller rotational speed - important at the waterhammer calculation and for viscosity correction calculation (see below);

   • diameter of the pump impeller - required only when calculating the flows of liquids containing a solid phase, since the correction of the pump characteristics by the solid phase depends on the diameter of the pump impeller. For liquids, this parameter can be omitted;

   • viscosity correction is factored into performance curve - when calculating the pumping of viscous liquids (with a viscosity over 4 cSt), the program automatically recalculates the pump head curve by viscosity according to the ANSI/HI method. However, if this correction is already taken into account in the pump head curve (for example, the pump manufacturer provided data on the pump's operation on a viscous liquid), then it is necessary to disable this recalculation by enabling this option. If this option is disabled, the recalculation by viscosity will be performed.

Pump curves are set point-by-point; buttons  to the left of the tables are used to add points to the tables:

• the top button adds a new point to the table of the head curve;

• the lower one – to the table of the NPSH curve;

• central – in both tables simultaneously.

The graphs of the pump head and net positive suction head dependencies on the flow rate are displayed as the control points are filled. The control points are written to the tables in ascending order of the flow rate value. To edit a point already specified in the table, right-click on the value you want to edit and select Edit. However, please note that you can only change the head or NPSH value in this way. Editing the flow rate value for a point is not available, so if you need to change the flow rate, you should delete the existing point and enter a new one in its place. To delete a point, right-click on it in the table (on the value in the table, not the point number) and select Delete.

One of the points of the pump head curve must be specified as the Best efficiency point (the point with the maximum pump efficiency) by checking the corresponding box while adding the point. On the graph, such a point is marked in yellow, and in the table - with an asterisk next to its number.

All the above pump characteristics can usually be found in pump passport data. For a more accurate approximation of pump curves, it is recommended to specify a large number of reference points (at least 3, but more is better). It is not allowed to specify pump characteristics consisting of only one point. If the pump passport does not include pump head vs. flow data, but indicates only, for example, the value of the nominal head/pressure and flow of the pump, in such cases, instead of the "Pump" element, it is recommended to use "Component with known change of pressure and/or temperature", for which the pump pressure difference can be specified manually.

The entered pump characteristics can be saved in a file with the .pmp extension for subsequent use in other pumps. To do this, use the Save to file and Load from file buttons.

Please note that from a hydraulic point of view, a pump is considered as a "point" (or "concentrated") resistance that has no length/width/height. Therefore, if it is necessary to take into account the pump dimensions in a diagram, they can be modeled as a pipe with the corresponding length and orientation in space. However, there is little practical interest in this, since, as a rule, the pump pressure value already includes pressure losses inside the pump and the hydrostatic drop on it. Therefore, it may be necessary to model the pump dimensions only in cases where the pump is located in a closed loop (so that the piping model looks correctly, without gaps).

Pump selection using Spaix

To select a pump in the Hydrosystem, it must be modeled as "Component with known change of pressure and/or temperature" with pressure drop equal to the required pump head (please note that this pressure drop in this case is specified with a minus sign since it should model the increasing of pressure). The required pump head must be pre-determined by calculation (for more information on such calculation, see here).

It is necessary to perform a calculation (isothermal or heat analysis) for this pipeline, after which in the Object Properties Window for this component the button "Spaix Pump Selection…" will appear, when clicked, the application "Spaix 4 Pumps" (if installed on the computer) will be launched to select the pump. All the information necessary for selecting the pump (required pressure, flow, properties of the pumped fluid, etc.) will be automatically transferred to Spaix:

In Spaix, the user will need to select the manufacturer and the preferred pump type, after which, by clicking the Next button, all suitable pumps of this type will be shown. If there are no suitable pumps for the given conditions in this category, Spaix will inform you about this in the corresponding window (in this case, click the Next button to return to the choice of manufacturer and pump type):

If there are suitable pumps, their list with basic characteristics will be displayed in the corresponding window:

Here you need to select the desired pump and, if necessary, adjust its configuration parameters. After confirming the pump selection in Spaix, its parameters (head and NPSH curves, range of operation limits, rotational speed, etc.) will be transferred to the Hydrosystem. This component with known change of pressure and/or temperature will be converted to a pump element and the pipeline will be recalculated with the selected pump. To cancel the pump selection and return to the original component with known change of pressure and/or temperature, use the Cancel command in the Edit menu or Edit toolbar.

For more detailed information on how Spaix 4 Pumps works, please refer to the documentation/help for this software.