General
Naturally Gassed calculates the size‑related requirements of the piping, fittings, and valves of a sole‑source natural gas or liquified petroleum (LP) gas piping system to provide sufficient flow and pressure at the appliances (outlets) served by the source.
The calculation methodologies incorporated are the piping pressure loss equations and the fitting and valve pressure loss methodology from Appendix A — Sizing and Capacities of Gas Piping — of the 2021 International Fuel Gas Code (IFGC), and Annex B — Sizing and Capacities of Gas Piping — of the 2021 NFPA 54/ANSI Z223.1, National Fuel Gas Code (NFGC).
Segments
All of the pipe segments from the gas supply to the appliances served are input. The input for each segment includes the length, the valves, and other components, as applicable.
Elbow quantities are automatically assigned to each segment; however, the quantities can be overridden. See Elbows for additional information.
Sizes also are automatically assigned to each segment; however, the sizes of the individual segments can be overridden. See Sizes for additional information.
Pressure
The pressure loss of each segment is calculated using the equations in the IFGC and in NFPA 54/ANSI Z223.1.
K‑factors are used to determine the equivalent lengths of fittings (elbows and tees) and valves.
Each appliance is assigned an independent required pressure.
The pressure required at the gas supply is the sum of the pressure losses of the segments serving the critical path appliance plus the pressure required at that appliance.
Sizes
Multiple profiles can be created for the automatic sizing of segments. Each profile includes all of the sizes (1/2" to 18"), with a flow range for each size.
The sizes assigned by the profiles can be overridden for each segment; however, doing so reduces the automatic sizing effectiveness.
Additionally, a “solver” (Excel goal seek) generates profiles by calculating the flow rates corresponding to an input pressure loss rate, with a single click.
Groups
Appliances can be assigned in groups, thereby allowing for individual segments to serve multiple appliances and expediting data entry.
Elbows
Multiple profiles can be created for automatically adding elbows to segments. Each profile has a length‑to‑elbow‑quantity ratio for each size.
The number of elbows assigned by the profiles can be overridden for each segment.
Diversities
Diversities can be applied to both individual appliances and to convenience outlets, to accommodate piping systems that have modulating and/or cycling appliances and outlets.
Features
- Supports both Inch‑Pound (I‑P) and International System (SI) units.
- 240 segments.
- 1/2" to 18" pipe.
- 40 pipe types (pipe roughnesses and inside diameters).
- 8 sets of automatic elbow profiles.
- 8 groups of appliances.
- 7 appliances per group, appliance quantity unlimited.
- 48 appliances.
- Diversities assignable to every appliance.
- 4 convenience outlets.
- 7 convenience outlet diversity profiles.
All of the data is editable!
Limitations
“Tree” type systems only are supported; systems where there is more than one path from the gas supply to any appliance are not supported.
Naturally Gassed is not inherently a critical path calculator. However, where (by experience) the critical path is apparent, Naturally Gassed can be used as a critical path calculator. Doing so, however, reduces the utility of Naturally Gassed with respect to automatic pipe sizing.
Other Considerations
The low‑pressure and high‑pressure formulas of IFGC Section 402.4 and NFGC Section 6.4.1 are not used. All conditions being the same, the IFGC Appendix A Section A104 and NFGC Annex B Section B.5 formulas generally result in slightly higher pressure drops than the IFGC Section 402.4 and NFGC Section 6.4.1 formulas.