QPCalc for Gas can be used for quickly calculating the isothermal pressure drop or flow rate in a pipe segment. English and SI-Metric units are handled.

First the units of calculations are chosen using the menu item Options/Units. The demo version will run only in English units and has limits in input data.

The pipe length, diameter, wall thickness and pipe absolute roughness can be specified for the segment along with the pipe efficiency (a decimal number less than 1.0). The gas properties such as specific gravity (air = 1.0), viscosity and the gas specific heat ratio (k = Cp/Cv) along with the base values of pressure and temperature are entered.

Choose a pressure drop formula and the compressibility factor calculation method from the drop down combo box. Choices available for pressure drop formula are AGA Turbulent, Colebrook-White, Darcy-Weisbach, General Flow Equation, IGT, Panhandle A or B and Weymouth equation. Three options are available for compressibility factor calculations: Standing-Katz, AGA NX-19 and CNGA methods.

Enter the flow rate in the pipe segment along with the gas flow temperature. The pipe elevations are ignored.

If the inlet pressure is to be calculated, leave that field blank and enter the desired outlet pressure and the flow rate. If the inlet pressure of the pipe segment is known, the outlet pressure can be calculated for a specified flow rate. Of the three items: flow rate, inlet pressure and outlet pressure, given two items, the third can be calculated.

If you choose Option/Defaults from the pull down menu, all fields will be cleared and the default values will be loaded. Clicking the Clear all menu will blank out all input fields.

By choosing Option/Units from menu bar the following screen opens up

This screen is used to choose English or SI-Metric units of calculation. Options are available for two different sets of units for pipeline distance and flow rates. In English units, pipeline distances have to be in either miles or feet. Pipeline flow rates for English units can be in Billion standard cubic feet per day (BSCFD), Million standard cubic feet per day (MMSCFD), cubic feet per hour (ft3/hr), etc.

For SI-Metric units, options for distance are kilometers or meters and flow rates may be in Billion m3/day, Million m3/day, etc. Click OK to exit the screen, after selecting the units of calculations.

To calculate, click the Calculator button or the menu item titled Calculate

The calculated results, including flow rate, pressures, gas velocity at inlet and outlet, Reynolds number, transmission factor, friction factor and line pack are displayed in a separate screen as shown below:

Choosing Clear will blank out the calculated results area. The results can also be printed.

Technical support is provided for licensed users of the software for a period of sixty (60) days from the initial purchase date. Economical Annual Technical Support plans are available after the initial 60-day period. Minor upgrades and maintenance releases are posted at SYSTEK’s Web site for licensed users to download free of charge. Major upgrades are issued twice a year at special prices to current licensed users. Call or write for details of Technical Support plans. Multi-user and Network versions of QPCalc-Gas are available. Call or email us for pricing.