Equipment & Component Modeling

Yes. FluidFlow includes a built-in library of PD Pumps and Rotating PD Pumps. You can add custom pump models to the database once, making them available for all future projects. For complete details, refer to Modeling Positive Displacement Pumps in FluidFlow.

Yes. FluidFlow allows you to modify pump operating speed or impeller diameter directly in the Input Editor. This feature works when you've specified the minimum and maximum speed ranges or impeller diameter ranges for the pump in the database.

When you adjust either parameter, the software automatically applies the affinity laws to calculate the resulting effects on duty pressure rise, efficiency, power requirements, and NPSHr.

Yes. FluidFlow allows you to add custom pumps to the database with complete manufacturer performance data including head-flow curves, efficiency points, and NPSH requirements. This enables accurate equipment modeling for your specific applications. For step-by-step instructions, refer to Modeling Centrifugal Pumps in FluidFlow Using Manufacturer Data, which covers everything from database configuration to performance analysis, system optimization, and cavitation prevention.

When using centrifugal pumps with different fluids, the flow versus head curve remains consistent regardless of fluid density changes. This is because "head" (typically measured in meters or feet) is a fundamental characteristic that stays constant across fluids with different specific gravities.

For example, a pump that develops 100 feet of head will maintain this performance whether pumping water or seawater, though the pressure will vary proportionally with specific gravity. Manufacturers typically provide performance curves based on water (specific gravity, SG = 1.0) as the test fluid.

Although the head remains constant, power requirements change in direct proportion to fluid density. For low-viscosity fluids, this mainly affects the power curve while leaving the flow vs. head relationship largely unchanged. However, for high-viscosity applications, both the head and power curves may need adjustment.

In FluidFlow, no conversion is needed for the head and NPSH curves when changing fluids. You can convert the power to your fluid by multiplying the value from the curve by the ratio of your fluid's specific gravity to the specific gravity of the test water.

To change a pump's flow direction, modify the "Discharge Pipe (RED)" assignment in the Input Editor. Select the "Discharge Pipe (RED)" row and click the ... button on the right to select a different pipe number. The red dot on the flowsheet will move to indicate the new discharge side. This feature is especially helpful when your calculation shows flow moving in an unexpected direction.

Yes. FluidFlow supports control valve modeling with the following types:

These components are located in the "Controllers" tab of the Data Palette. For detailed instructions on modeling vendor-specific control valves or using the automatic sizing features, refer to the following comprehensive guide:

Control Valve Modeling in FluidFlow: Auto-Sizing and Manufacturer Data Integration

FluidFlow includes a database of manual valves (including gate, globe, butterfly, and ball valves). Valves not included in the database can be easily added and reused across multiple projects.

When adding a new valve to the database, you can define either a single K, Kv, Cv, or Kf value, or create a curve relationship of % open vs these values. The image below shows a sample valve with the required information:

Yes. Users can enter a value for valve opening % on the Input Editor for all manual valves. FluidFlow automatically calculates the corresponding K value and pressure loss based on current system conditions. When you adjust the opening percentage, the software recalculates the effects on overall system performance.

Yes, FluidFlow allows you to automatically size relief valves and bursting disks for liquid, gas, steam, and two-phase systems according to both API and ISO standards. When using the API method, the software also suggests the most appropriate standard API size for your consideration.

The software comes with a standard library of relief valve models and allows you to model specific manufacturers' relief valves. Engineers can expand this library by adding new models as needed.

For comprehensive guidelines on sizing relief valves, check Relief Valve Sizing Documentation. This covers liquid, gas, steam, and two-phase flow systems with detailed examples.

When modeling a relief valve, you can disable the "Automatically Size" function and manually define the relief valve data. You have the option to use either standard sizes or input non-standard orifice areas for your relief valve.

The software will then calculate the flow based on your specified parameters rather than automatically sizing the valve.

Yes. FluidFlow offers proprietary nodes for modeling pressure loss in non-standard fittings. You can select from K, Kf, Kv/Cv, or User-Defined Generic nodes. The User-Defined Generic node allows you to define a curve relationship of pressure loss as a function of flow rate for any fitting.

Yes. FluidFlow comes with a comprehensive library of fans and compressors. Engineers can easily expand this library by adding new equipment models as needed.

For detailed guidance, refer to Modeling Fan and Blower Performance Curves in FluidFlow Using Manufacturer Data.

FluidFlow does not include a dedicated eductor or ejector node.

The recommended approach is to model the system up to the device inlet and represent the eductor/ejector using either a known pressure or a known flow boundary. This boundary condition should be based on the manufacturer's specifications to ensure your system meets the required flow/pressure conditions.

For example, if you know the required inlet pressure for a specific flow rate, set up a known pressure boundary with this value, and FluidFlow will calculate the resulting flow for verification. Alternatively, if you define a flow at a known flow boundary, the software will determine the required pressure. Compare these calculated values with vendor requirements and establish appropriate tolerances based on your system's specific operating conditions and safety factors.

To model a submersible pump (which has no suction piping), insert a short section of pipe between the model inlet boundary and the pump suction connection to complete the model connectivity. You can set this pipe's status to "Ignore Pressure/Heat Loss" to eliminate any frictional losses in this section.

Yes, fire hydrants can be modeled in FluidFlow and are available from the Valves tab of the Component Palette. See Design Example 3 of the FluidFlow Fire Systems for a sample system, as shown below.

FluidFlow offers multiple options for assigning pressure loss:

All these options are available from the General Resistances tab of the Component Palette. The best choice depends on the data available for your specific application.

Spray balls are used for hygienic and industrial cleaning applications. They typically use high flow rate and low pressure to clean residue from the inside surfaces of tanks, milk silos, and similar vessels. The pressure loss relationship of a spray ball can be modeled in FluidFlow.

Figure 1 below illustrates a vendor spray ball capacity diagram.

Figure 1: Vendor Spray Ball Capacity Diagram.

To properly model a spray ball in FluidFlow using vendor specifications, follow these steps:

Step 1: Read several data points from the specific spray ball curve on the vendor's capacity diagram.

Step 2: Create a table of these data points in Excel or a similar spreadsheet.

Step 3: Generate a curve plot from this data and display the equation on the chart.

Figure 2: Spray Ball Capacity Diagram.

Step 4: Use the terms from this equation as input for the "User Defined Generic" node in FluidFlow.

Step 5: Configure the "User Defined Generic" node to define your spray ball.

Step 6: Verify your model by creating test cases with different flow rates.

Step 7: Compare the calculated pressure loss values with the vendor curve data to confirm accuracy.

Figure 3: Spray Ball Modeled as a User Defined Generic Node - FluidFlow.

Step 8: Once verified, incorporate this component into your system model.

The "User Defined Generic" node enables modeling of various non-standard fittings or devices. Components such as flame arrestors, check valves, spray balls, and others have all been successfully modeled using this component.

Dampers are specialty fittings used in rectangular ducts. While FluidFlow doesn't have a specific damper component, you can model them effectively using available resistance components.

Based on your vendor data for dampers (such as K values or Flow vs. Pressure Drop information), you can use:

The labyrinth seal element in FluidFlow is a custom component designed specifically for compressor oil seal applications for one of our customers. The calculations used are proprietary. For general applications, we recommend modeling labyrinth seals using a General Resistance K component. You can determine the appropriate K value from relevant charts or published literature.

To model a pipeline discharging to the atmosphere using a Known Pressure Boundary node with pipe exit losses, insert a K (General Resistance) node near the end of the line and set the K value to 1.0. This setup requires having a pipe between the K component and the Known Pressure node, which you can set to “Ignore Pressure/Heat Loss”. The same approach works for discharging into a pressurized vessel, where you can enter the vessel pressure at the outlet boundary.

FluidFlow offers four different methods for modeling pressure loss at tee junctions:

Modeling Tips:

For additional information about tees in FluidFlow, refer to below documentation:

Modeling Tee Junctions in FluidFlow

FluidFlow automatically corrects fan and blower performance based on actual flowing air density and pressure conditions. Here's how it works:

This automatic correction ensures accurate modeling of fan and blower performance across varying operating scenarios without manual adjustments.