Category » Modeling Systems & Components

There were 21 articles found in this category:

1. What is a "Reverse Return" System?
   A reverse return system is a type of closed loop system in which the return header is connected to the most hydraulically remote load, as shown in Figure 1. Compared to the direct return system in Figure 2 in which the return header is connected to the load closest to the pump, the reverse retu ...
2. Static Head in Systems with Varying Fluid Temperatures
   What is static head and how is the static head calculated for a system that contains a fluid at different temperatures? The static head of a system is that portion of the pump’s Total Head that must be added to the fluid before a single drop of fluid will move in the system. It is the amo ...
3. New Custom Shapes / Symbols for PIPE-FLO and Flow of Fluids
   Several new shapes and symbols have been created for use in the PIPE-FLO and Flow of Fluids programs. These shapes can be downloaded and installed from the Attachments section at the bottom of this article. Simply click on New Custom Shapes & Symbols.exe, and either run the file, or save it to ...
4. HVAC Flow Control Methods
   An HVAC piping system is designed to convey a heat transfer fluid to multiple air handlers, providing cooling (chilled water) or heating (hydronic heating) loads in a building. A typical HVAC system consists of a primary loop and a secondary loop. The primary loop contains the chiller or boiler ...
5. Finding the Most Hydraulically Remote Loop
   If you have set the system flow rate with one or more fixed flow pumps, you will need to leave one of the system loops uncontrolled (i.e. set the loop FCV to the fully open position). The loop that you need to leave uncontrolled is the most hydraulically remote loop (the one with the largest pr ...
6. Newtonian and Non-Newtonian Fluids
   PIPE-FLO can be used to analyze systems with Newtonian fluids. The program does not handle Non-Newtonian fluids. A fluid is defined as a substance that undergoes continuous deformation when subjected to a shear stress. The resistance of the fluid to this deformation is ordinarily measured in t ...
7. The Difference Between Total and Static Properties
   PIPE-FLO Compressible calculates both total and static pressure values. This article reviews the difference between total and static properties. Total (Stagnation) Property - A point in a flow field in which the flow is brought to rest is called a stagnation point, and properties at that point ...
8. Pipeline Velocity Increases in Compressible Fluid Systems
   For compressible fluids (in which density is not a constant), the fluid velocity increases as the flow progresses through a pipeline. At first, this fact may seem counterintuative to some users. Under normal subsonic conditions, the velocity of a compressible fluid tends to increase as the flui ...
9. Valve & Fitting Losses in PIPE-FLO Stock
   Generally, the loss coefficient (K value) for pulp suspensions in a given valve or fitting exceeds the loss coefficient for water in the same valve or fitting. In all regions of the friction loss curve for pulp, the loss due to valves and fittings is added to the pulp friction loss and is comput ...
10. Standard Flow Rate Units
    PIPE-FLO Compressible has six different standard flow rate units to choose from. The following standard US flow rate units are available: scfm (standard cubic feet per minute) scfh (standard cubic feet per hour) scfs (standard cubic feet per second) These units are based on a reference condition ...
11. Adding SCFM units in PIPE-FLO
    When dealing with compressible fluid, it is often desirable to use standard flow rate units (based on the fluid properties of the gas at 60 F, and 14.7 psia. This knowledge base article describes how to add SCFM to units in PIPE-FLO. It is often necessary to perform compressible fluid calculati ...
12. System Resistance Curve Overview
    The system resistance curve is a plot of a piping system's total resistance over a range of flow rates. The system resistance curve can be a very useful tool to have when selecting a pump. In the construction of the system resistance curve, losses due to pipe friction, valves and fittings, and ...
13. Manually Generating a System Resistance Curve
    The system resistance curve is a plot of a piping system's total resistance over a range of flow rates. You can automatically generate a system resistance curve in PIPE-FLO, however this feature has the following limitations: There can only be one active pump in the system (all other pumps ar ...
14. When to Break a Pipeline into Segments
    There are four reasons for breaking a pipeline into multiple segments. The pipe diameter, pipe specification, or fluid zone changes The flow branches from a single pipeline into multiple pipelines, or converges from multiple pipelines into a single pipeline To obtain a pressure at a given lo ...
15. Troubleshooting an Existing HVAC System
    PIPE-FLO Professional can be used to design new systems as well as to analyze existing ones. For the example HVAC system, we will quickly determine why we are not getting the required flow rates in the air handler loops and then try out a proposed solution to the problem. Also, using PIPE-FLO ...
16. Analyzing a Compressible Fluid System with PIPE-FLO Professional
    Since PIPE-FLO Professional uses the Darcy-Weisbach method to calculate pipeline pressure losses, an iterative method must be employed in some cases when analyzing compressible fluid systems. This article discusses the restrictions for using the Darcy-Weisbach method on compressible fluid syste ...
17. The Hydraulic Grade
    The Bernoulli theorem states that the total energy of the fluid anywhere in the system is composed of three components: the pressure head, the velocity head, and the elevation head. This relationship is expressed in the following way: H = P/r + v²/2g + Z H = total head P = gage pressure r = flui ...
18. Pumping into a Partially Full Pipeline
    Often it is necessary to pump into a pipeline that may or may not be full of liquid. A user was unable to get the needed results because the discharge pipeline in her system was full under high pumping demands, and partially full under low pumping demands. This article describes how to use PI ...
19. Equivalent Lengths
    When the equivalent length method is used to account for valve and fitting losses, the valve/fitting loss is expressed as a length which is added to the actual pipeline length. When the equivalent length is substituted into the Darcy-Weisbach equation, the loss due to the valve/fitting is as fo ...
20. Pumping Over a High Point
    When placing a pump into a piping system with a high point, the following items must be determined: The total head needed to overcome the pressure drop in the pipeline from the source and destination tank. The static head needed to pump the liquid up to the high point The back pressure requi ...