PIPE-FLO Compressible calculates the balanced flow rates and pressures in piping systems transporting steam and industrial gases. This easy-to-use program shows you how the entire piping system operates. Using the calculated results, you can determine the flow rate in each pipeline, the pressure at each pipeline junction, along with details on the operation of compressors, control valves, and components. This section describes the methodology used to perform these calculations.

Pipeline Pressure Drop Calculations

For compressible flows through pipelines such things as friction, area change, heat transfer, and the addition of mass can affect the state of the flow. The flow is categorized as simple flow if only one of these effects is present, for example, an area change occurs without friction, heat transfer, or a mass addition. PIPE-FLO Compressible assumes that the flow is simple. For most compressible systems, this provides results well within the range of acceptable engineering accuracy.

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

Engineering Data Tables

PIPE-FLO Compressible accesses pipeline data, gas properties, and valve & fitting data in the engineering data tables. The customer can customize the content of the engineering data tables using the supplied Table Manager program. You can create your own tables, modify existing data tables, or install manufacturers' tables.

PIPE-FLO Compressible assumes the ideal gas law for the equation of state. For the accuracy required in many engineering flow computations, air, steam, and many other common gases behave as ideal gases. PIPE-FLO Compressible contains a library of fluid property data for a wide range of industrial gases. The user can create a fluid data table, or manually enter the fluid properties to handle gases not available in a table.

The standard valve and fitting table shipped with PIPE-FLO contains the entire valve and fitting types found in the Crane Technical Paper 410. Custom valve and fitting tables can be created for various materials and pipe specifications.

The PIPE-FLO Compressible network calculations incorporate a number of advanced numerical solutions techniques, including three penalty minimization techniques (steepest decent, Hardy Cross, and a genetic algorithm) as well as a flow-averaging algorithm, a pressure averaging algorithm, and the Newton-Raphson method. The program performs the network balancing calculations using a combination of these methods, choosing the best method to drive the solution. This insures that the optimal method is used for each type of system during all phases of the calculation process.

The program automatically sets up the network calculations by tracing the system loops and setting up the flow and pressure drop equations needed to preform the calculations.

Control Valve Selection & Evaluation

Control valve sizing is performed using the method outlined in the Instrument Society of America Standard ISA S75.01 Flow Equations for Sizing Control Valves. Electronic Control Valve Catalogs provide the information needed for control valve selection and evaluation. Control valves can be manually entered into the piping system model, allowing any manufacturer's valves to be modeled.

Flow Meter Sizing

Flow meter and balance orifice sizing is performed using the method outlined in the American Society of Mechanical Engineers Standard ASME MFC-3M Measurement of Fluid Flow in Pipes Using Orifice, Nozzle, and Venturi.

Detailed Program Methodology

A detailed method of solution is available at the following links: