When should I use PIPE-FLO Compressible instead of PIPE-FLO Professional?

PIPE-FLO Compressible calculates the physical properties of the gas as it flows through the piping system. In addition, PIPE-FLO Compressible calculates when the fluid flow in a pipeline is approaching the sonic velocity or choked flow conditions.

PIPE-FLO Compressible can be used for any piping system transporting gas or steam as the process fluid, but PIPE-FLO Compressible is the only application that should be used under the following conditions:

• Long runs of pipelines typically found in gas transmission systems.
• Systems with large pressure drops such as vent and relief headers.
• Large changes in pipe diameter.
• Low-pressure vacuum systems.

Why should I use PIPE-FLO Compressible when my spreadsheet provides me with the results I need?

Spreadsheets only calculate the pressure drop of a single pipeline for a given flow rate.

In addition to calculating the pressure drop in a single pipeline, PIPE-FLO Compressible also:

• Calculates the flow rates and pressures in the entire piping system by performing a total network analysis.
• Incorporates blowers, compressors, and control valves into the piping system model, showing you how the entire piping system operates.
• Considers alternate operating conditions for the system and shows how the system operates.
• Shows where choked flow conditions exist in your compressed gas system.

PIPE-FLO Compressible provides you with a total system view instead of a head loss calculation for a single pipeline.

What are the assumptions used in PIPE-FLO Compressible?

PIPE-FLO Compressible assumes an adiabatic process (no heat transfer) with no mass addition or removal. The two flows handled by the program are Fanno flow (flow with friction) and simple area changes.

What are the limits as to the number of pipelines and nodes PIPE-FLO Compressible can handle?

There are no program limits as to the maximum number of pipelines, nodes, tanks, compressors, or any other item in the piping system model. PIPE-FLO Compressible dynamically allocates the memory needed to perform the calculations, thus eliminating any program limits. It addition it makes more effective use of your computer's memory.

What pipe materials does PIPE-FLO Compressible support?

PIPE-FLO Compressible uses engineering data tables to look up the pipe data needed to perform the pressure drop calculations. The program comes with a variety of pipe size tables based on published pipe standards. You select the pipe material and schedule or wall thickness and the program presents the available nominal sizes. The program looks up the inside diameter and uses that value in the pressure drop calculations.

Can I create my own pipe size tables, or modify the tables shipped with the software?

Yes. Using the supplied Table Manager program, you can load pipe tables, modify the pipe tables shipped with the program, or create your own custom pipe size tables for specialty pipe material.

What valves and fittings does the program support?

The valve table supplied with the program contains all the valves and fittings found in the Crane Technical Paper 410. The user selects the valve or fitting and the program calculates the loss coefficient. Specialty valve and fitting tables are available from selected manufacturers as well.

What if the supplied table doesn't have the valves and fittings I use?

You can enter any valve or fitting into your piping system model by entering either the K value, Cv value, or the differential pressure for a given flow rate. In addition, using the Table Manager program you can create your own custom valve and fitting tables.

What gases does the program support?

PIPE-FLO Compressible looks up the fluid information in engineering data tables. It comes with a fluid compilation of over 100 gases and steam. You can also create custom fluids in your projects by entering the fluid properties, allowing you to model any gas for use with PIPE-FLO Compressible.

Can I model compressors and blowers in the piping system?

Yes. The program supports both centrifugal and positive displacement blowers and compressors. Centrifugal devices are modeled by entering performance data of flow rate and discharge pressure for a range of flows.

Can PIPE-FLO Compressible handle liquids as well as compressible gases?

No PIPE-FLO Compressible only works with gases and steam.

What convergence method does PIPE-FLO Compressible use to calculate the balanced flow rates and pressures?

PIPE-FLO Compressible employs the following convergence methods:

• Steepest Decent
• Hardy Cross
• Genetic Algorithm
• Flow Averaging
• Pressure Averaging
• Newton-Raphson

The program employs all methods simultaneously, the results produced by the best method is used as the starting point for all methods in the next iteration. This insures the program has the highest probability to converge to a solution in the least number of iterations.

What happens if PIPE-FLO Compressible cannot converge to a solution?

Regardless of which convergence method is used, there are cases in which the program may be unable to converge to a solution. The program uses a genetic algorithm that increases the probability a solution can be reached.

If the PIPE-FLO Compressible program is unable to converge to a solution, it is most likely due to a physical problem in the real piping system. In such a case, it is important to know where the problem exists in the physical piping system. As the program performs the calculations, you can see which pipelines in the piping system are experiencing choked or sonic flow. In addition, you can stop the calculation at any time, review the intermediate results, and restart the calculation. This is a great time saver when troubleshooting a piping system design.

If you have additional questions about PIPE-FLO Compressible, please feel free to contact Engineered Software.