FlowDesigner Glossary
This technical glossary provides quick reference definitions of hydraulic analysis concepts and FlowDesigner software features. Topics range from fundamental fluid mechanics principles—like absolute roughness and affinity laws—to specific FlowDesigner capabilities, including Case Modes, Insight Charts, Scenarios, SmartSelect, and various calculation methods.
A
Absolute Roughness
Denoted as ε, it is a critical parameter for determining friction factors in turbulent flow.
It provides a measure of the microscopic irregularities on the internal surface of a pipe, expressed in units of length (such as mm or inches). It represents the actual physical height of surface irregularities that increase friction and turbulence in fluid flow.
Affinity Laws
Mathematical relationships that describe how centrifugal pump, compressor or blower performance parameters (flow rate, head, and power) change with variations in impeller diameter or rotational speed.
Formula:
Q2 / Q1 = (N2 / N1) (D2 / D1)
H2 / H1 = (N2 / N1)2 (D2 / D1)2
P2 / P1 = (N2 / N1)3 (D2 / D1)3
Where
Qn
Booster volumetric flowrate at point “n”
Nn
Booster impeller shaft speed at point “n”
Hn
Generated booster head at point “n”
Pn
Booster duty power required at point “n”
Dn
Booster impeller size at point “n”
Used in FlowDesigner for developing cost optimization strategies through variation of impeller size or speed to improve efficiency, increase capacity and maximize utilization of existing assets.
Ambient Pressure
The pressure of the surrounding environment where a hydraulic system operates. It serves as the reference point for gauge pressure measurements.
Ambient pressure is essential for accurate pressure differential calculations and for determining proper equipment operating conditions. FlowDesigner uses it as a baseline for pressure-related calculations, particularly for open systems or tanks exposed to atmospheric conditions.
Ambient Temperature
The temperature of the surrounding environment where a hydraulic system operates. It affects fluid properties and heat transfer calculations in FlowDesigner models.
Ambient temperature influences fluid viscosity, density, and vapor pressure—all of which directly impact flow behavior and system performance. FlowDesigner incorporates ambient temperature in heat loss calculations and for determining accurate fluid properties under various operating conditions.
ANSI 9.6.7
American National Standard for Rotodynamic Pumps - Guidelines for Effects of Liquid Viscosity on Performance.
This guideline can be applied in calculations by ticking the checkbox in the calculation options dialog box under the global settings tab. It would automatically adjust water-based centrifugal pump performance curves when pumping Newtonian liquids with kinematic viscosities of 4.3 cSt or higher to account for viscosity effects.
Assigned Flow Node
Boundary node in FlowDesigner that represents a flow condition at the system entrance or exit point.
The user specifies the flow direction for this node. When set to "Into Network," the node becomes an inlet boundary, revealing additional fields for fluid and temperature data.
The solver calculates the pressure required to achieve the defined flow.
Assigned Pressure Node
Boundary node in FlowDesigner that represents pressure at the system entrance or exit point.
The solver automatically determines the flow direction based on the model's configuration, analyzing whether this node should drive flow into the network or receive flow from it.
The solver calculates the achievable flow rate based on the defined pressure.
Atmospheric Pressure
The pressure exerted by the weight of Earth's atmosphere, typically 101.325 kPa (14.7 psia) at sea level. It varies with altitude and weather conditions.
In FlowDesigner, atmospheric pressure serves as the reference point for gauge pressure measurements and is critical for calculating NPSH, modeling open tanks, and designing pressure relief systems. Accurate atmospheric pressure settings ensure proper representation of system behavior, particularly for systems that interact with the atmosphere.
B
Backpressure
Pressure downstream of an in-line pipe equipment such as relief valve or control device. This parameter is applied as guide when sizing or evaluating equipment performance for capacity, flashing and unwanted two-phase flow at the discharge.
Best Efficiency Point (BEP)
Duty point on the centrifugal pump performance curve where pump efficiency and reliability is at their maximum and thus the most favored operating point.
In pump selection and evaluation, performance within 130% of BEP is typically considered acceptable, while attaining 90% - 110% of BEP is considered best practice.
Bend
Fitting used to join conduits to redirect orientation at a certain angle.
The change in flow direction cause additional pressure losses which can be modeled using any of the following methods:
Rennels & Hudson
Crane TP410
3-K Darby
Miller
Idelchik
Bill of Materials
Comprehensive list of all components, pipes, and equipment in a hydraulic model, automatically generated for procurement and cost estimation.
Boosters
Mechanical devices that transport fluid from source to destination by increasing fluid pressure. In FlowDesigner, boosters include centrifugal and positive displacement pumps.
Boundaries
Start and end nodes of a FlowDesigner hydraulic model.
The node where the model begins or from which fluid information is sourced for calculations is known as the "inlet boundary," while the endpoint is commonly referred to as the "outlet boundary."
FlowDesigner has a wide selection of boundary nodes available:
Assigned Pressure
Assigned Flow
Reservoir
Open Pipe
Sprinkler Nozzle
Branch Angle
Angle at which junctions connect pipes with each other. This information is used as one of the basis in calculation junction pressure loss.
Bursting Disk
Non-reclosing pressure relief device designed to rupture at a predetermined pressure, providing overpressure protection by relieving dangerous pressure or vacuum buildup.
When modeling a bursting disk, users define its certified resistance coefficient “Kr” with its friction losses calculated using resistance to flow method.
C
Calculation Settings
Adjustable parameters that control how FlowDesigner performs hydraulic calculations, accessible via the Calculation tab of Application Settings. These include physical parameters, calculation tolerances, iteration limits, and transient settings.
Case Modes
Case mode is a key FlowDesigner feature that determines equipment size or evaluates the performance of fluid transport equipment with a certain characteristic.
Accessible through the Input Panel, case modes offer two calculation types:
Design: Determines the required size or hydraulic characteristics of fluid transport equipment.
Rating: Simulates the performance of specific equipment specifications or characteristics in a hydraulic model.
Case modes are available for the following components:
Pumps
Orifices
Control Valves
Sprinklers
Relief Valves
Cavitation
Phenomena where the local liquid pressure falls below its vapor pressure, resulting to formation of bubbles that collapses and cause a mechanically damaging energy release on exposed surfaces.
Check Valve
Valve used to protect pump and piping systems by preventing the reversal of flow and hence are unidirectional.
Typical applications are on the discharge side of a booster where backflow could damage the internals of the equipment and cause an unnecessary shutdown of the system.
These check valve types can be modeled in FlowDesigner:
Swing Check Valve
Tilting Disk Check Valve
Stop Check Valve
Lift Check Valve
Centrifugal Pump
Pump type that create work to increase fluid pressure by using the rotational energy of its impeller.
The impeller's rotation introduces kinetic energy to the liquid, causing it to move outward due to centrifugal force. As the fluid moves outward, its velocity decreases, converting kinetic energy into pressure energy at the discharge.
Centrifugal Pump Basic Hydraulic Criteria
Basic checkpoints for evaluating centrifugal pump performance:
Achieving duty point
Proximity to best efficiency point (BEP)
Adequacy of NPSHA versus NPSHR
Centrifugal Pump Performance Curve
Centrifugal pump performance curves are provided by manufacturers to present details on the resulting differential head, efficiency, power or required NPSHR as flow, impeller size or speed is varied for a given pump model.
This information can be installed in hydraulic models upon storage in the component databank and upon engaging the “Rating” case mode.
Application of centrifugal pump performance curve in models enable determination of actual pump performance against hydraulic performance criteria to determine its suitability for the intended service.
Component
Individual element in a FlowDesigner model representing physical equipment such as pumps, valves, pipes, or fittings.
Component Chart
Graphical display of component hydraulic characteristics in a FlowDesigner model accessible through the Input Panel.
Insight Chart
Graphical display of hydraulic characteristics exhibited by two or more components in a hydraulic model in any of the following form:
Flowpath HGL/EGL Chart
Valve Authority Chart
Variations Chart
Connection Rules
Connection rules are basic philosophies in FlowDesigner used as guide when linking one pipe to another.
In summary, the rules are:
Pipe always end in nodes
Pipes must always end at a node connection. Hence, a pipe with no other connection would always terminate with an open pipe end.
Deleting a node where a pipe is connected will also delete the pipe.
Smart junction placement
Pipe junctions adjust automatically depending on the number of connecting pipes up to a maximum of four. Two connecting pipes generate an elbow or a bend; three, a tee or a wye; and four connections, a cross.
Default junctions can accommodate a maximum of four (4) pipe connections using a cross.
Unlimited connection
A connector can accommodate over four (4) connections.
No invalid connections
Invalid connections are automatically prevented. For instance, users cannot connect a third pipe connection to a pump or a fifth connection to a cross junction.
Unlimited boundary connection
The Reservoir node is the only boundary with fluid and temperature definition capable of accommodating more than one (1) pipe connection.
Pipe Splitting
Inserting a pipe to pipe connection forces its original input length to be defined according to pipe data application settings. It can either be split into two equal lengths or duplicate the pipe length data.
Pipe Merging
Deleting a node between two pipe will cause a length definition equal to the sum of the two pipe lengths.
When two pipes with different sizes are connected with each other, the larger pipe size will be applied as input data.
Connectors
Connectors are junction types that do not generate pressure losses but introduce pipe inlet and exit losses.
It is typically used to model junctions requiring more than four (4) pipe connections.
Control Valve
Used to model different devices for controlling flow, pressure or temperature at a given point in a fluid transport system.
A control valve can be any of the following:
Pressure Reducing Control Valve
Pressure Sustaining Control Valve
Differential Pressure Control Valve
Flow Control Valve
Control valves can be set to Design mode to determine preliminary valve Cv values, or Rating mode to simulate system performance using control valve manufacturer data.
Convergence
The point during iteration when calculated variables such as flow, pressure, or temperature no longer change beyond defined tolerance limits.
Correlation
Empirical formulas that represent a relationship between two data and is used as a reference to determine a variable from another.
Cv
Valve characteristic that describes the amount of flow passing through the valve for every pressure drop generated. It is expressed in terms of US gallons per minute measured per 1 psi pressure drop at 60°F.
For control valves, FlowDesigner calculates Cv using ANSI/ISA-75.01.01-2007 standards.
Cross Junction
Cross junctions are junction types that do not generate pressure losses and cater four (4) pipe connections.
D
Databank
An organized collection of fluid properties and component manufacturer specifications that streamlines model development by reducing manual data entry.
The FlowDesigner Databank includes:
Fluid Databank
Component Databank (for centrifugal pumps and control valves)
Users can access, customize, and expand the Databank to include project-specific or proprietary data, ensuring consistency across models and projects.
Darcy - Weisbach Equation
Fundamental formula used for calculating pressure loss due to friction in pipe flow expressed as:
ΔP = f × (L / D) × (ρ V2 / 2)
Where:
ΔP
Pressure Drop
f
Moody Friction factor
L
Pipe length
D
Pipe diameter
ρ
Fluid density
V
Fluid velocity
Density
Mass of a substance per unit volume of space occupied
Design Case
Case mode that determines the equipment characteristics needed to meet a specified requirement.
Differential Head
Difference in total head between two points in a hydraulic system.
It’s commonly used when referring to:
Head added by the pump (differential head)
Head loss across a component (pipe, valve, heat exchanger, etc.)
Directional Components
Modeling components that require flow direction definition—such as boosters, check valves, flow control valves, and tees—visually recognizable by a red triangle marking indicating flow direction.
Driver
Device used to supply mechanical energy to a booster (i.e. pump or compressor). Depending on requirements, it can be a motor, turbine or engine.
Duty Efficiency
Pump efficiency achieved at the pump duty point.
Duty Flow
Pump flow output for a given pump head developed.
Duty NPSH Available
Head difference between pump suction nozzle pressure and the liquid vapor pressure.
It is a pump suction system characteristic that influences pump selection and is required to be higher than the Duty NPSH Required to prevent cavitation.
Duty NPSH Required
Minimum head difference between pump suction nozzle pressure and the liquid vapor pressure needed by a certain pump model to avoid cavitation.
It is a unique pump characteristic specified by pump manufacturers and is greatly influenced by pump design and flow rate.
In pump selection, Duty NPSH Available should always be higher than Duty NPSH Required.
FlowDesigner performs this comparison and generate warning messages accordingly.
Duty Point
Achievable flow and differential head of a certain pump model against the resulting system flow resistance.
In pump performance chart analysis, it is recognized as the intersection of the pump performance and system curves.
Duty Power
Power sent by the pump driver to the liquid at a given duty point.
Duty Pressure Rise
Head developed by the pump at duty flow. See Differential Head.
E
Efficiency
Ratio between hydraulic power to the power supplied by the driver represented in percentage form. It provides a measure on the effectiveness of energy conversion from driver power source to mechanical energy into absorbed by the fluid during transport.
EGL
Acronym for "Energy Grade Line," a graphical insight chart representing the total head available to a fluid at any point along the flow path.
Element
Basic building block of a hydraulic model. It represents individual system components or segments, each with specific properties and behaviors.
Elevation
Distance at a certain point in a system measured vertically from a reference point.
Elevation Gradient
Vertical distance differential between two points measured using the same reference point.
F
Flowsheet
The space allotted in FlowDesigner for placing and connecting hydraulic model components.
Flow Regime
General characteristic pattern of fluid movement within a pipe or channel characterized by Reynolds number.
Laminar
Maximum (1500 - 3000)
Turbulent
Minimum (2000 - 6000)
Intermediate
In-between laminar maximum and turbulent minimum
The specific Reynolds number values defining laminar and turbulent flow boundaries vary based on engineering experience and industry-specific practices.
Fluid
A substance either in the form of liquid, gas or a combination of both that has no fixed shape and tends to flow in response to an applied force.
G
Generic K Resistance
Node for representing pressure loss coefficient. It represents the directly proportional relationship of head loss (or pressure drop) to the square of velocity arriving to the expression:
ΔP = K × (ρV2 / 2)
Pressure loss coefficients can be applied across different fluids. According to DS Miller, these coefficients are not unique to a specific fluid but instead function as universal relationships to Reynolds number for a given geometry.
Where:
ΔP
Pressure drop
ρ
Fluid Density
V
Fluid Velocity
Generic Kf Resistance
Node that represents a resistance coefficient derived from Crane TP-410, expressed by the following formula:
Kf = fT (L / D)
Where:
fT
Turbulent flow friction factor
L/D
Equivalent length of a resistance to flow
Generic Kv Resistance
General resistance node used to simulate pressure drop variability with flow for fittings, manual valves, piping equipment, or combinations thereof through the following relationship:
ΔP = (ρRef/ρ)n-1 (m/mRef)n ΔPRef
Where:
ΔP
Calculated pressure drop
ρRef
Reference fluid density for the corresponding reference pressure loss (ΔPRef)
ρ
Fluid Density
m
Fluid mass flow rate passing through the Kv node
mRef
Reference fluid mass flow for the corresponding reference pressure loss (ΔPRef)
ΔPRef
Reference pressure loss
n
Relationship exponent, typically applies a value of 2.0
H
HGL
Acronym for "Hydraulic Grade Line," a graphical insight chart in FlowDesigner.
It represents the total head available to a fluid at a specific point in the flow path, excluding kinetic energy (velocity head).
Hydraulic Power
Amount of energy per unit time absorbed by the fluid during pumping or compression.
I
Impeller
Rotating component of a pump or compressor that features vanes or blades designed to increase fluid kinetic energy, consequently converted to pressure at the discharge point.
Inlet Boundary
A fundamental component of any solvable model, represented as a boundary node that provides fluid and temperature data for the solver.
Inlet boundaries are not manually assigned but automatically determined based on the node's configuration to drive flow toward the system.
Some of these configurations are:
When two Assigned pressure nodes at the same elevation are connected to each other, and one node has a higher pressure setting, the solver automatically selects the node with the higher pressure as the inlet boundary component.
For boundary nodes both specified with the same pressure setting, the relative elevation between them also serves as a basis for selection.
When using an Assigned flow node, setting the flow direction to "Into Network" instructs the solver to treat that node as an inlet boundary. This forces the solver to calculate a boundary pressure that establishes the node as the fluid source.
If a boundary node is connected to the suction side of a booster or flow control valve, it will also require the solver to use its data as inlet boundary.
Input Panel
User interface feature in FlowDesigner for entering and editing data, displaying and configuring property tables, images, text, and other flowsheet objects.
Intermediate Flow
Also known as transition flow, this regime is typically found to occur at Reynolds numbers between 2300 and 4000.
This flow regime is associated with unstable flow patterns, making it undesirable for fluid transport, heat transfer and measurement.
Isometric Mode
A 3D visualization option in FlowDesigner. Enable it by clicking the Toggle Grid Style button in the bottom right corner of the flowsheet area.
J
Junction
Nodes used to model pipe connections that combine, split flow, or change pipe direction which can either be:
Connector
Bends
Tee or Wye
Cross Junction
Except for connectors, all other junction can be automatically generated on the flowsheet when making pipe connections, following pipe connection rules.
Junction Pressure Drop Loss Model
For bends, tees and wyes, the calculation of pressure drop applies the K-factor pressure loss relationship:
ΔP = K × (ρV2/2)
Where the pressure loss coefficient K can be evaluated using any of these junction pressure loss correlations:
Idelchik
Miller
SAE
Crane
L
Laminar Flow
Observed at Reynolds number less than 3000, this flow regime is characterized by smooth, orderly fluid motion where fluid moves in parallel layers with minimal mixing between layers.
M
Minimum Allowable Flow Rate
Lowest acceptable flow rate for specific pump model needed to prevent recirculation, overheating, and other mechanical issues.
Typically specified in pump curve database entry as checkpoint during performance evaluation.
During calculations, the software displays a warning message if the pump operates below its specified minimum flow rate.
Moody Friction Factor
Dimensionless parameter applied by the Darcy - Weisbach equation that quantifies the friction loss incurred for a certain fluid, flow velocity, pipe size, length and flow regime:
Laminar Flow:
fD = 64/Re
Turbulent Flow (Colebrook (a) / Haaland (b) Equation):
1/√(f)=-2 Log [ε/3.7D+2.51/(Re√f)]
1/√(f)=- Log [(ε/3.7D)1.11 + 2.51/Re]
Haaland equation is used when the user selects the non-iterative solution for friction factor calculation in the Calculation options.
Where:
f
Friction factor
D
Pipe diameter
Re
Reynolds Number
ε
Pipe absolute roughness
For systems where flow regime falls within transition, a linear interpolation using the friction factor at the Reynolds number where laminar flow terminate and turbulent regime start is applied.
N
Newtonian Fluid
Fluid whose viscosity is always constant at a given temperature.
In viscometry, it generates a linear shear rate vs. shear stress plot starting at the origin.
Nodes
Components in FlowDesigner hydraulic models where pipes connect, defining system topology and flow paths.
Nominal Diameter (DN)
Standard pipe size designation, approximately equal to the internal diameter. Expressed in whole numbers (millimeters) rather than exact measurements, as per ISO standards.
Nominal Pipe Size (NPS)
Standard pipe size designation, approximately equal to the internal diameter. Expressed in whole numbers (inches) rather than exact measurements, as per American standards (ANSI/ASME).
Notifications
Provides feedback about calculation status, warnings about potential issues, or errors preventing model convergence. It provide engineers the means to identify and resolve modeling issues for reliable analysis. Accessible through the Notifications button in the Results Viewer, located at the bottom right of the interface.
NPSH
Acronym for Net Positive Suction Head, a parameter used to design or examine pumps to predict the possibility of cavitation.
It refers to the difference between the pressure or head at the pump suction inlet and the fluid's vapor pressure.
NPSHA
Acronym for Net Positive Suction Head Available, refers to the difference between the pressure or head at the pump suction inlet and the fluid's vapor pressure at a particular pump flow rate.
NPSHR
Acronym for Net Positive Suction Head Required, refers to the minimum pressure difference between the pump suction inlet and the fluid's vapor pressure required by a specific pump model to operate at a particular flow rate without cavitation.
O
Operating Speed
Refers to the booster shaft rotational speed which influence pump performance in accordance to affinity laws.
Orifice
Circular plate device with a sized bore at the center inserted in pipes to create pressure drop to restrict or measure fluid flowrate.
Orthogonal Mode
A 2D visualization option in FlowDesigner. Enable it by clicking the Toggle Grid Style button in the bottom right corner of the flowsheet area.
Outlet Boundary
A fundamental component of any solvable model, a boundary node that represents the termination point of a hydraulic model.
Unlike inlet boundaries, it requires only either flow or pressure definition for the solver to complete its calculation.
P
Piezometric Pressure
Total pressure at a specific point in a system, accounting for both the static (actual) pressure and the elevation head above a reference point.
Pipe
An enclosed conduit used to transport fluids. These are circular in cross-section and available in widely varying sizes, wall thicknesses, and materials.
Pipes are specified in terms of their diameter and wall thickness, which can also be indicated by the schedule number.
Positive Displacement Pump
Pump type that creates work to increase fluid pressure by trapping a fixed volume of liquid in a chamber or cavity and then physically displacing it by mechanical means such as a piston, diaphragm, or gear in a repetitive cyclic process.
As the chamber decrease in size, the trapped liquid is forced out, generating flow and increasing its pressure to move toward the discharge.
Pressure Gradient
Pressure differential between two points measured at the same reference point.
Pressure Model
In Assigned pressure boundaries, this refers to the manner on pressure is defined: either as stagnation or static pressure.
Safety Relief Valve
Safety device that limits pressure in a system during abnormal conditions by releasing fluids to a safe location.
In FlowDesigner, safety valves are sized according to orifice bore size. When case mode is set to Rating, it can also be used to evaluate the performance of a safety relief valve for a particular model using manufacturer data.
R
Rating Case
This case mode simulates the performance of an equipment using its defined characteristics in a hydraulic model.
R/D Ratio
Ratio of bend radius to pipe diameter of an elbow junction used as data for calculating pressure loss
Resistance
Component group in FlowDesigner used for modeling flow resistance characteristics of specialty equipment not readily representable by other component groups.
Results Table
Displays calculation results for all pipes and nodes in the flowsheet. Access it using the bottom-most button in the Results Viewer.
Results Viewer
Located in the bottom right of the interface, the Results Viewer provides access to FlowDesigner's calculation results through the following buttons:
Results Table - displays calculation results for all components in the flowsheet
Notifications - shows messages about convergence and calculation results
Costs - provides access to cost-related charts
Reynolds Number
Represents the ratio of the inertial force to the viscous forced exerted on the fluid.
This dimensionless parameter is applied to characterize flow regime by quantifying the momentum of a fluid or the inertial forces compared to the internal friction or fluid viscosity.
At high Reynolds number, inertial forces dominate leading to turbulent flow, while at lower values signify that viscous forces are influential, resulting in smooth, laminar flow.
It is calculated using the expression:
Re = DVρ/μ
Where:
D
Pipe internal diameter
V
Fluid velocity
ρ
Fluid density
μ
Fluid viscosity
S
Scenarios
Predefined sets of operating conditions and system configurations in FlowDesigner allowing engineers to analyze multiple system configuration using a single model to enable:
Easier comparison of alternatives
Elimination of file duplication for minor configuration changes
Reduced input errors across multiple model configuration
Size Change
General classification of components that cause sudden change of fluid velocity during transport. Typically caused by change in size of inlet and outlet pipes or by a sudden constriction.
The following size change devices are available in FlowDesigner:
Thin Orifice
Thick Orifice
Expander or Reducer
Abrupt Size Change
Sizing Model
Framework for determining equipment specifications using a defined requirement during “Design” case mode.
Available sizing models include:
Pumps: Size for Flow, Size for Head Rise
Sprinklers: Specify Nominal K, Specify Design Flow
Orifices: Size for Flow, Size for dP
SmartSelect
Advanced tool in FlowDesigner for rapidly exploring alternative pipe and equipment specifications from manufacturer databases based on hydraulic calculations and use-defined criteria.
Sprinkler Nozzle
An active fire protection device that discharges water to a specific area to extinguish fires or provide cooling in case of a fire emergency.
These devices can be modeled in FlowDesigner as outlet boundaries to determine whether flow requirements for each destination can be met based on a defined exit pressure.
Stagnation Pressure
Pressure exerted by a fluid when brought to rest, combining static and velocity pressure.
In measurement terms, this is the pressure reading obtained from a pitot tube-type gauge where pressure is measured at the pipe's center, a point where friction loss is zero and velocity is at a maximum.
One of the pressure models available in FlowDesigner. This model is recommended for pressure-type boundary conditions, especially for systems with large storage tanks or atmospheric boundaries where the associated volume remains relatively constant over time and fluid velocity can be assumed negligible.
Static Pressure
Pressure exerted by a fluid at rest.
In measurement terms, this is the pressure reading obtained from a gauge whose measurement is taken at the pipe wall, a point where fluid velocity is zero.
One of the pressure models available in FlowDesigner. This model is recommended for systems that do not start at a physical boundary such as a vessel or reservoir but rather a particular location in a pipe network.
System Curve
Graphical representation showing how total pressure drop in a system or component varies with flow.
These curves are generated in individual pipes or pumps accessible through the component charts in the Input Panel.
T
Tee
Fitting used to join three conduits that split or merge two flow streams.
Modeled in FlowDesigner using any of these pressure loss relationships:
Rennels & Hudson
Crane TP410
Miller
Idelchik
Transition Flow
See Intermediate Flow
Turbulent Flow
Flow regime characterized by chaotic, irregular fluid motion where eddies and swirls dominate. Typically observed at Reynolds number of 4000 or higher.
U
Units of Measurement System of measurement units that can be configured according to user preferences through Application Settings.
V
Valve
Mechanical device installed in a piping system to regulate, stop, reroute, or isolate fluid flow.
Valve flow resistance characteristics are defined using K, Kf, Kv, or Cv values when modeling. Valve positioning data versus Cv or Kv can also be used to accurately model valve performance.
FlowDesigner supports the following valve types:
Butterfly
Diaphragm
Ball
Gate
Globe
Angle
Plug
Pinch
Y-Globe
Needle
Slide
Vapor Pressure
Pressure at which a liquid begins to vaporize at a specific temperature.
This fluid property is commonly investigated in liquid transport systems where cavitation or two-phase flow issues are likely to occur.
Variations
Advanced feature that enables quick and systematic execution of multiple model calculations using a defined range of input data, making optimization and sensitivity studies in FlowDesigner easier.
X
Xt Factor
Pressure loss ratio factor that predicts the point at which flow becomes choked, where further pressure drop doesn't increase flow due to sonic velocity limitations at the vena contracta.
This information is obtained from valve manufacturers and can be unique to certain valve types and models.
% Opening
Refers to the degree of valve opening, typically expressed as a percentage of full travel, which directly affects the valve's flow capacity and pressure loss characteristics.
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This glossary covers the fundamental terms used in FlowDesigner and fluid flow engineering. For detailed explanations, calculations, and practical applications, explore our comprehensive knowledge base.
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