CPC · California Plumbing Code
Required gas supply, outlet sizing, and pipe sizing tables
This hub explains where the CPC sets required gas supply, minimum outlet sizes, and the table‑ and equation‑based methods (Table 1215.2 / Equation 1215.3) used to size gas piping.
Last reviewed: July 6, 2026
Overview
This section of the California Plumbing Code (CPC) covers how to determine required gas supply (appliance demand and minimum outlet sizes), how to convert appliance input to volumetric demand, and how to select pipe diameters using the CPC’s prescriptive tables or sizing equations. The CPC establishes appliance demand guidance in Table 1208.3.1 and sets minimum outlet sizes (1/2" for typical appliance supply outlets; 3/4" for mobile homes) under §1214.0 and §1214.4 .
Accurate sizing prevents under‑pressure at appliance inlets and excessive pressure drop along runs. The code provides three table-based/graphical sizing methods — Longest Length, Branch Length, and Hybrid Pressure — and also permits sizing by equations (Equation 1215.3) or standard engineering methods when conditions fall outside the tables. See §1215.0 et seq. for the tables (Table 1215.2 series) and the sizing equations and procedures used to select pipe sizes and equivalent lengths .
Key CPC locations to consult when working on gas piping are the fuel‑gas chapter sections on appliance input and sizing methods (for example §1208.3.2), the required gas supply rules at §1214.0, and the required piping size and tables at §1215.0 through §1215.3 (including Table 1215.2 for material‑specific tables and Equation 1215.3 for smooth‑wall tubing) .
In this section
Code references
Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:
CPC § 1214.1 High relevance — show source text
1214.1 General. The following regulations shall comply with this section and Section 1215.0, shall be the standard for the installation of gas piping. Natural gas regulations and tables are based on the use of a gas having a specific gravity of 0.60 and for undiluted liquefied petroleum gas, having a specific gravity of 1.50. Where gas of a different specific gravity is to be delivered, the specific gravity conversion factors provided by the serving gas supplier shall be used in sizing piping systems from the pipe sizing tables in this chapter.
1214.2 Volume. The hourly volume of gas required at each piping outlet shall be taken as not less than the maximum hourly rating as specified by the manufacturer of the appliance or appliances to be connected to each such outlet.
1214.3 Gas Appliances. Where the gas appliances to be installed have not been specified, Table 1208.3.1 shall be permitted to be used as a reference to estimate requirements of typical appliances. To obtain the cubic feet per hour (m [3] /h) of gas required, divide the input of the appliances by the average Btu (kW•h) heating value per cubic foot (m [3] ) of the gas. The average Btu (kW•h) per cubic foot (m [3] ) of the gas in the area of the installation shall be permitted to be obtained from the serving gas supplier.
1214.4 Size of Piping Outlets. The size of the supply piping outlet for a gas appliance shall be not less than [1] ⁄ 2 of an inch in diameter (15 mm).
The size of a piping outlet for a mobile home shall be not less than [3] ⁄ 4 of an inch in diameter (20 mm).
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1215.0 Required Gas Piping Size. 1215.1 Pipe Sizing Methods. Where the pipe size is to be determined using any of the methods in Section 1215.1.1 through Section 1215.1.3, the diameter of each pipe segment shall be obtained from the pipe sizing tables in Section 1215.2 or from the sizing equations in Section 1215.3. [NFPA 54:6.1]
1215.1.1 Longest Length Method. The pipe size of each section of gas piping shall be determined using the longest length of piping from the point of delivery to the most remote outlet and the load of the section. [NFPA 54:6.1.1] (see calculation example in Figure 1215.1.1)
1215.1.2 Branch Length Method. Pipe shall be sized as follows:
(1) Pipe size of each section of the longest pipe run from the point of delivery to the most remote outlet shall be determined using the longest run of piping and the load of the section.
(2) The pipe size of each section of branch piping not previously sized shall be determined using the length of piping from the point of delivery to the most remote outlet in each branch and the load of the section. [NFPA 54:6.1.2]
CPC § 1323.1.4 High relevance — show source text
1323.1.4 Maximum Demand. Where the maximum demand for each medical gas or vacuum system does not exceed the values in Table 1323.1.4(1) through Table 1323.1.4(6), the size of pipe of each section of the system shall be determined in accordance with Section 1323.1.5. The size for systems beyond the range of Table 1323.1.4(1) through Table 1323.1.4(6) shall be determined in accordance with Section 1323.1.6.
1323.1.5 Sizing Procedures. The size of each section of pipe in a system within the range of Table 1323.1.4(1) through Table 1324.1.4(6) shall be determined in accordance with the following:
(1) Determine the total flow rate and number of outlets or inlets for each section of pipe in accordance with Table 1305.2 and Table 1305.3.
(2) Measure the length of the section of pipe to each station outlet or inlet on the system. Multiply the measured pipe length by 1.5 (150 percent), to account for the number of fittings in the system, to determine the pipe equivalent length.
(3) Beginning with the most remote outlet or inlet, multiply the total flow rate by the diversity factor specified in Table 1323.1.5(1) for each section of pipe to determine the sizing flow rate for the piping.
(4) Select Table 1323.1.4(1) through Table 1324.1.4(6) based on the medical gas or vacuum being transported through the piping.
(5) Select an estimated pipe size for determining the system pressure loss. Multiply the pipe equivalent length, for a given section of pipe, by the pressure loss for the sizing flow rate in the applicable table. Divide that number by 100 to determine the system pressure loss for the section of pipe.
(6) Add the pressure loss for each section of piping, from the source equipment location to the outlet or
inlet, to determine the total system pressure loss to each outlet or inlet. The total system pressure loss in the piping to each outlet or inlet shall not exceed the values specified in Table 1323.1.5(2).
TABLE 1323.1.5(1) SYSTEM SIZING – FLOW REQUIREMENTS FOR STATION OUTLETS AND INLETS [1]
NUMBER OF
OUTLETS AND
INLETS
TERMINAL
UNITS PER
FACILITYDIVERSITY
PERCENTAGE OF
AVERAGE FLOW
PER OUTLETS
AND INLETS
TERMINAL UNITSMINIMUM PERMISSIBLE
SYSTEM FLOW OF ALL
PRESSURIZED MEDICAL
GAS SYSTEMS2
(standard cubic feet per minute)
1–10100% Actual Demand
11–2575% 7.0
26–5050% 13.1
51–10050% 17.5 Notes: 1 Flow rates of station outlets and inlets in accordance with Table 1305.2. 2 The minimum system flow is the average outlets and inlets flow times the number of station outlets and inlets times the diversity percentage.
TABLE 1323.1.5(2) MAXIMUM PERMITTED PRESSURE LOSS IN
CPC § 0.249 High relevance — show source text
water column = 0.249 kPa
TABLE 1215.3
Cr AND Y FOR NATURAL GAS AND UNDILUTED
PROPANE AT STANDARD CONDITIONS
[NFPA 54: TABLE 6.4.2]
GAS FORMULA FACTORS Col3
GASCr Y
Natural Gas0.6094 0.9992 Undiluted Propane 1.2462 0.9910 1215.4 Sizing of Piping Sections. To determine the size of each section of pipe in a system within the range of Table 1215.2(1) through Table 1215.2(36), proceed as follows:
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(1) Measure the length of the pipe from the gas meter location to the most remote outlet on the system.
(2) Select the length in feet column and row showing the distance, or the next longer distance where the table does not give the exact length.
(3) Starting at the most remote outlet, find in the row just selected the gas demand for that outlet. Where the exact figure of demand is not shown, choose the next larger figure in the row.
(4) At the top of this column will be found the correct size of pipe.
(5) Using this same row, proceed in a similar manner to each section of pipe serving this outlet. For each section of pipe, determine the total gas demand supplied by that section. Where gas piping sections serve both heating and cooling appliances and the installation prevents both units from operating simultaneously, the larger of the two demand loads needs to be used in sizing these sections.
(6) Size each section of branch piping not previously sized by measuring the distance from the gas meter location to the most remote outlet in that branch and follow the procedures of steps 2, 3, 4, and 5 above. Size branch piping in the order of their distance from the meter location, beginning with the most distant outlet not previously sized.
1215.5 Engineering Methods. For conditions other than those covered by Section 1215.1, such as longer runs or greater gas demands, the size of each gas piping system shall be determined by standard engineering methods acceptable to the Authority Having Jurisdiction, and each such system shall be so designed that the total pressure drop between the meter or another point of supply and an outlet where full demand is being supplied to all outlets, shall be in accordance with the requirements of Section 1208.4. 1215.6 Variable Gas Pressure. Where the supply gas pressure exceeds 5 psi (34.6 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane or is less than 6 inches (1.5 kPa) of water column, or where diversity demand factors are used, the design, pipe, sizing, materials, location, and use of such systems first shall be approved by the Authority Having Jurisdiction. Piping systems designed for pressures exceeding the serving gas supplier’s standard delivery pressure shall have prior verification from the gas supplier of the availability of the design pressure.
CPC § 1215.5 High relevance — show source text
(6) Size each section of branch piping not previously sized by measuring the distance from the gas meter location to the most remote outlet in that branch and follow the procedures of steps 2, 3, 4, and 5 above. Size branch piping in the order of their distance from the meter location, beginning with the most distant outlet not previously sized.
1215.5 Engineering Methods. For conditions other than those covered by Section 1215.1, such as longer runs or greater gas demands, the size of each gas piping system shall be determined by standard engineering methods acceptable to the Authority Having Jurisdiction, and each such system shall be so designed that the total pressure drop between the meter or another point of supply and an outlet where full demand is being supplied to all outlets, shall be in accordance with the requirements of Section 1208.4. 1215.6 Variable Gas Pressure. Where the supply gas pressure exceeds 5 psi (34.6 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane or is less than 6 inches (1.5 kPa) of water column, or where diversity demand factors are used, the design, pipe, sizing, materials, location, and use of such systems first shall be approved by the Authority Having Jurisdiction. Piping systems designed for pressures exceeding the serving gas supplier’s standard delivery pressure shall have prior verification from the gas supplier of the availability of the design pressure.
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FIGURE 1215.1.1
EXAMPLE ILLUSTRATING USE OF TABLE 1208.3.1 AND TABLE 1215.2(1)
Problem: Determine the required pipe size of each section and outlet of the piping system shown in Figure 1215.1.1. Gas to be used has a specific gravity of 0.60 and 1100 British thermal units (Btu) per cubic foot (0.0114 kW•h/L), delivered at 8 inch water column (2.0 kPa) pressure.
For SI units: 1 foot = 304.8 mm, 1 gallon = 3.785 L, 1000 British thermal units per hour = 0.293 kW, 1 cubic foot per hour = 0.0283 m [3] /h
Solution:
(1) Maximum gas demand of Outlet A — 32 cubic feet per hour (0.91 m [3] /h) (from Table 1208.3.1).
Maximum gas demand of Outlet B — 3 cubic feet per hour (0.08 m [3] /h) (from Table 1208.3.1).
Maximum gas demand of Outlet C — 59 cubic feet per hour (1.67 m [3] /h) (from Table 1208.3.1).
Maximum gas demand of Outlet D — 136 cubic feet per hour (3.85 m [3] /h) [150 000 Btu/hour (44 kW) divided by 1100 Btu per cubic foot (0.0114 kW•h/L)].
(2) The length of pipe from the gas meter to the most remote outlet (Outlet A) is 60 feet (18 288 mm).
CPC § 1215.0 High relevance — show source text
The size of a piping outlet for a mobile home shall be not less than [3] ⁄ 4 of an inch in diameter (20 mm).
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1215.0 Required Gas Piping Size. 1215.1 Pipe Sizing Methods. Where the pipe size is to be determined using any of the methods in Section 1215.1.1 through Section 1215.1.3, the diameter of each pipe segment shall be obtained from the pipe sizing tables in Section 1215.2 or from the sizing equations in Section 1215.3. [NFPA 54:6.1]
1215.1.1 Longest Length Method. The pipe size of each section of gas piping shall be determined using the longest length of piping from the point of delivery to the most remote outlet and the load of the section. [NFPA 54:6.1.1] (see calculation example in Figure 1215.1.1)
1215.1.2 Branch Length Method. Pipe shall be sized as follows:
(1) Pipe size of each section of the longest pipe run from the point of delivery to the most remote outlet shall be determined using the longest run of piping and the load of the section.
(2) The pipe size of each section of branch piping not previously sized shall be determined using the length of piping from the point of delivery to the most remote outlet in each branch and the load of the section. [NFPA 54:6.1.2]
1215.1.3 Hybrid Pressure. The pipe size for each section of higher pressure gas piping shall be determined using the longest length of piping from the point of delivery to the most remote line pressure regulator. The pipe size from the line pressure regulator to each outlet shall be determined using the length of piping from the regulator to the most remote outlet served by the regulator.
[NFPA 54:6.1.3] 1215.2 Sizing of Gas Piping Systems. Sizing of piping systems shall be in accordance with Section 1215.2.1 for natural gas piping systems and Section 1215.2.2 for propane piping systems. 1215.2.1 Natural Gas Piping Systems. Table 1215.2(1) through Table 1215.2(23) shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for piping materials other than non-corrugated stainless steel tubing. Section 1215.3 shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for non-corrugated stainless steel tubing.
CPC § 1314.2 High relevance — show source text
Where gas of a different specific gravity is to be delivered, the serving gas supplier shall be permitted to be contacted for specific gravity conversion factors to use in sizing piping systems from the pipe sizing tables in this chapter. 1314.2 Volume. The hourly volume of gas required at each piping outlet shall be taken as not less than the maximum hourly rating as specified by the manufacturer of the appliance or appliances to be connected to each such outlet.
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1314.3 Gas Appliances. Where the gas appliances to be installed have not been definitely specified, Table 1308.3.1 shall be permitted to be used as a reference to estimate requirements of typical appliances. To obtain the cubic feet per hour (m [3] /h) of gas required, divide the input of the appliances by the average Btu (kW•h) heating value per cubic foot (m [3] ) of the gas. The average Btu (kW•h) per cubic foot (m [3] ) of the gas in the area of the installation shall be permitted to be obtained from the serving gas supplier. 1314.4 Size of Piping Outlets. The size of the supply piping outlet for a gas appliance shall be not less than [1] ⁄ 2 of an inch (15 mm). The size of a piping outlet for a mobile home shall be not less than [3] ⁄ 4 of an inch (20 mm).
1315.0 Required Gas Piping Size. 1315.1 Pipe Sizing Methods. Where the pipe size is to be determined using any of the methods in Section 1315.1.1 through Section 1315.1.3, the diameter of each pipe segment shall be obtained from the pipe sizing tables in Section 1315.2 or from the sizing equations in Section 1315.3. [NFPA 54:6.1] 1315.1.1 Longest Length Method. The pipe size of each section of gas piping shall be determined using the longest length of piping from the point of delivery to the most remote outlet and the load of the section. [NFPA 54:6.1.1] 1315.1.2 Branch Length Method. Pipe shall be sized as follows:
(1) Pipe size of each section of the longest pipe run from the point of delivery to the most remote outlet shall be determined using the longest run of piping and the load of the section.
(2) The pipe size of each section of branch piping not previously sized shall be determined using the length of piping from the point of delivery to the most remote outlet in each branch and the load of the section. [NFPA 54:6.1.2] 1315.1.3 Hybrid Pressure. The pipe size for each section of higher pressure gas piping shall be determined using the longest length of piping from the point of delivery to the most remote line pressure regulator. The pipe size from the line pressure regulator to each outlet shall be determined using the length of piping from the regulator to the most remote outlet served by the regulator. [NFPA 54:6.1.3] **1315.2 Sizing of Gas Piping Systems.
CPC § 1315.3 High relevance — show source text
TABLE 1315.3
Cr AND Y FOR NATURAL GAS AND UNDILUTED
PROPANE AT STANDARD CONDITIONS
[NFPA 54: TABLE 6.4.2]
GAS FORMULA FACTORS Col3
GASCr Y
Natural Gas0.6094 0.9992 Undiluted Propane 1.2462 0.9910 1315.4 Sizing of Piping Sections. To determine the size of each section of pipe in a system within the range of Table 1315.2(1) through Table 1315.2(36), proceed as follows:
(1) Measure the length of the pipe from the gas meter location to the most remote outlet on the system.
(2) Select the length in feet column and row showing the distance, or the next longer distance where the table does not give the exact length.
(3) Starting at the most remote outlet, find in the just selected the gas demand for that outlet. Where the exact figure of demand is not shown, choose the next larger figure in the
row.
(4) At the top of the column in the table will be found the correct size of pipe.
(5) Using this same row, proceed in a similar manner for each section of pipe serving this outlet. For each section of pipe, determine the total gas demand supplied by that section. Where gas piping sections serve both heating and cooling appliances and the installation prevents both units from operating simultaneously, the larger of the two demand loads needs to be used in sizing these sections.
(6) Size each section of branch piping not previously sized by measuring the distance from the gas meter location to the most remote outlet in that branch and follow the procedures of steps 2, 3, 4, and 5 above. Size branch piping in the order of their distance from the meter location, beginning with the most distant outlet not previously sized.
1315.5 Engineering Methods. For conditions other than those covered by Section 1315.1, such as longer runs or greater gas demands, the size of each gas piping system shall be determined by standard engineering methods acceptable to the Authority Having Jurisdiction, and each such system shall be so designed that the total pressure drop between the meter or other point of supply and an outlet where full demand is being supplied to outlets, shall be in accordance with the requirements of Section 1308.3.
1315.6 Variable Gas Pressures. Where the supply gas pressure exceeds 5 psi (34 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane or is less than 6 inches (1.5 kPa) of water column, or where diversity demand factors are used, the design, pipe, sizing, materials, location, and use of such systems first shall be approved by the Authority Having Jurisdiction. Piping systems designed for pressures exceeding the serving gas supplier’s standard delivery pressure shall have prior verification from the gas supplier of the availability of the design pressure.
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CPC § 1211.7 High relevance — show source text
1211.7 Electrical Connections . . . . . . . . .229
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TABLE OF CONTENTS
1211.8 Earthquake-Actuated Gas Shutoff Valves . . . . . . . . . . . . . . . .229
1212.0 Appliance and Equipment Connections to Building Piping . . .229
1212.1 Connecting Appliances and Equipment . . . . . . . . . . . . . . . . . .229
1212.2 Suspended Low-Intensity Infrared Tube Heaters . . . . . . . . .230
1212.3 Use of Nonmetallic Gas
Hose Connectors . . . . . . . . . . . . .230
1212.4 Injection (Bunsen) Burners . . . . . .230
1212.5 Connection of Portable
and Mobile Industrial
Gas Appliances . . . . . . . . . . . . . .230
1212.6 Appliance Shutoff Valves and Connections . . . . . . . . . . . . . .230
1212.7 Quick-Disconnect Devices . . . . . .230
1212.8 Gas Convenience Outlets . . . . . .231
1212.9 Sediment Trap . . . . . . . . . . . . . . .231
1212.10 Installation of Piping . . . . . . . . . . .231
1212.11 Liquefied Petroleum Gas Facilities and Piping . . . . . . . . . . .231
1213.0 Pressure Testing, Inspection, and Purging . . . . . . . . . . . . . . . . .231
1213.1 Piping Installations . . . . . . . . . . . .231
1213.2 Test Preparation . . . . . . . . . . . . . .231
1213.3 Test Pressure . . . . . . . . . . . . . . . .232
1213.4 Detection of Leaks and Defects . .232
1213.5 Piping System Leak Test . . . . . . .232
1213.6 Purging Requirements . . . . . . . . .232
Table 1213.6.1 Size and Length of Piping . . . . . .232
1214.0 Required Gas Supply . . . . . . . . . .233
1214.1 General . . . . . . . . . . . . . . . . . . . . .233
1214.2 Volume . . . . . . . . . . . . . . . . . . . . .233
1214.3 Gas Appliances . . . . . . . . . . . . . .233
1214.4 Size of Piping Outlets . . . . . . . . . .233
1215.0 Required Gas Piping Size . . . . . .234
1215.1 Pipe Sizing Methods . . . . . . . . . . .234
1215.2 Sizing of Gas Piping Systems . . .234
1215.3 Sizing Equations . . . . . . . . . . . . . .234
Table 1215.3 Cr and Y for Natural Gas
CPC § 1315.5 Medium relevance — show source text
(6) Size each section of branch piping not previously sized by measuring the distance from the gas meter location to the most remote outlet in that branch and follow the procedures of steps 2, 3, 4, and 5 above. Size branch piping in the order of their distance from the meter location, beginning with the most distant outlet not previously sized.
1315.5 Engineering Methods. For conditions other than those covered by Section 1315.1, such as longer runs or greater gas demands, the size of each gas piping system shall be determined by standard engineering methods acceptable to the Authority Having Jurisdiction, and each such system shall be so designed that the total pressure drop between the meter or other point of supply and an outlet where full demand is being supplied to outlets, shall be in accordance with the requirements of Section 1308.3.
1315.6 Variable Gas Pressures. Where the supply gas pressure exceeds 5 psi (34 kPa) for natural gas and 10 psi (69 kPa) for undiluted propane or is less than 6 inches (1.5 kPa) of water column, or where diversity demand factors are used, the design, pipe, sizing, materials, location, and use of such systems first shall be approved by the Authority Having Jurisdiction. Piping systems designed for pressures exceeding the serving gas supplier’s standard delivery pressure shall have prior verification from the gas supplier of the availability of the design pressure.
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FIGURE 1315.1.1 EXAMPLE ILLUSTRATING USE OF TABLE 1308.3.1 AND TABLE 1315.2(1) Problem: Determine the required pipe size of each section and outlet of the piping system shown in Figure 1315.1.1. Gas to be used has a specific gravity of 0.60 and 1100 British thermal units (Btu) per cubic foot (0.0114 kW•h/L), delivered at 8 inch water column (1.9 kPa) pressure.
For SI units: 1 foot = 304.8 mm, 1 gallon = 3.785 L, 1000 British thermal units per hour = 0.293 kW, 1 cubic foot per hour = 0.0283 m [3] /h
Solution:
(1) Maximum gas demand of Outlet A – 32 cubic feet per hour (0.91 m [3] /h) (from Table 1308.3.1).
Maximum gas demand of Outlet B – 3 cubic feet per hour (0.08 m [3] /h) (from Table 1308.3.1).
Maximum gas demand of Outlet C – 59 cubic feet per hour (1.67 m [3] /h) (from Table 1308.3.1).
Maximum gas demand of Outlet D – 136 cubic feet per hour (3.85 m [3] /h) [150 000 Btu/hour (44 kW)] divided by 1100 Btu per cubic foot (0.0114 kW•h/L)
(2) The length of pipe from the gas meter to the most remote outlet (Outlet A) is 60 feet (18 288 mm).
CPC § 0.293 Medium relevance — show source text
automatic storage
30 to 40 gallon tank
Water heater, automatic storage
50 gallon tank
Water heater, automatic instantaneous
Capacity at 2 gallons per minute
Capacity at 4 gallons per minute
Capacity at 6 gallons per minute
Water heater, domestic, circulating or
side-arm|
35 000
50 000
142 800
285 000
428 400
35 000| |
Cooking Appliances
Range, freestanding, domestic
Built-in oven or broiler unit, domestic
Built-in top unit, domestic|
65 000
25 000
40 000| |
Other Appliances
Refrigerator
Clothes dryer, Type 1 (domestic)
Gas fireplace direct-vent
Gas log
Barbecue
Gaslight|
3000
35 000
40 000
80 000
40 000
2500|For SI units: 1000 British thermal units per hour = 0.293 kW
1208.3.2 Sizing Methods. Gas piping shall be sized in accordance with one of the following:
(1) Pipe sizing tables or sizing equations in this chap ter.
(2) Sizing tables included in a listed piping system manufacturer’s installation instructions.
(3) Engineering methods. [NFPA 54:5.3.3]
1208.3.3 Allowable Pressure Drop. The design pressure loss in a piping system from the point of delivery to
TABLE 1208.3.1
APPROXIMATE GAS INPUT FOR
TYPICAL APPLIANCES
[NFPA 54: TABLE A.5.3.2.1]
«
«
«
«
«
For SI units: 1000 British thermal units per hour = 0.293 kW
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«
«
«
«
«
«
«
«
«
«
1208.5.4 Plastic Pipe, Tubing, and Fittings. Polyethylene plastic pipe, tubing, and fittings used to supply fuel gas shall conform to ASTM D2513. Pipe to be used shall be marked “gas” and “ASTM D2513.” Polyamide pipe, tubing, and fittings shall be identified in and conform to ASTM F2945. Pipe to be used shall be marked “gas” and “ASTM F2945.” Polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC) plastic pipe, tubing, and fittings shall not be used to supply fuel gas. [NFPA 54:5.5.4.1.1 – 5.5.4.1.3]
1208.5.5 Regulator Vent Piping. Plastic pipe and fittings used to connect regulator vents to remote vent terminations shall be PVC (Schedule 40 and 80). PVC vent piping shall not be installed indoors. {NFPA 54:5.5.4.2}
CPC § 1213.6.2.1 Medium relevance — show source text
1213.6.2.1 Purging Procedure. The piping system shall be purged in accordance with one or more of the following:
(1) The piping shall be purged with fuel gas and shall discharge to the outdoors.
(2) The piping shall be purged with fuel gas and shall discharge to the indoors or outdoors through an appliance burner not located in a combustion chamber. Such burner shall be provided with a continuous source of ignition.
(3) The piping shall be purged with fuel gas and shall discharge to the indoors or outdoors through a burner that has a continuous source of ignition and that is designed for such pur pose.
(4) The piping shall be purged with fuel gas that is discharged to the indoors or outdoors, and the point of discharge shall be monitored with a listed combustible gas detector in accordance with Section 1213.6.2.2. Purging shall be stopped when fuel gas is detected.
(5) The piping shall be purged by the gas supplier in accordance with written procedures. [NFPA 54:8.3.2.1]
1213.6.2.2 Combustible Gas Detector. Com bustible gas detectors shall be listed and calibrated or tested in accordance with the manufacturer’s
instructions. Combustible gas detectors shall be capable of indicating the presence of fuel gas.
[NFPA 54:8.3.2.2]
1213.6.3 Purging Appliances and Equipment. After the piping system has been placed in operation, appliances and equipment shall be purged before being placed into operation. [NFPA 54:8.3.3]
1214.0 Required Gas Supply.
1214.1 General. The following regulations shall comply with this section and Section 1215.0, shall be the standard for the installation of gas piping. Natural gas regulations and tables are based on the use of a gas having a specific gravity of 0.60 and for undiluted liquefied petroleum gas, having a specific gravity of 1.50. Where gas of a different specific gravity is to be delivered, the specific gravity conversion factors provided by the serving gas supplier shall be used in sizing piping systems from the pipe sizing tables in this chapter.
1214.2 Volume. The hourly volume of gas required at each piping outlet shall be taken as not less than the maximum hourly rating as specified by the manufacturer of the appliance or appliances to be connected to each such outlet.
1214.3 Gas Appliances. Where the gas appliances to be installed have not been specified, Table 1208.3.1 shall be permitted to be used as a reference to estimate requirements of typical appliances. To obtain the cubic feet per hour (m [3] /h) of gas required, divide the input of the appliances by the average Btu (kW•h) heating value per cubic foot (m [3] ) of the gas. The average Btu (kW•h) per cubic foot (m [3] ) of the gas in the area of the installation shall be permitted to be obtained from the serving gas supplier.
1214.4 Size of Piping Outlets. The size of the supply piping outlet for a gas appliance shall be not less than [1] ⁄ 2 of an inch in diameter (15 mm).
The size of a piping outlet for a mobile home shall be not less than [3] ⁄ 4 of an inch in diameter (20 mm).
CPC § 1215.1.2 Medium relevance — show source text
1215.1.2 Branch Length Method. Pipe shall be sized as follows:
(1) Pipe size of each section of the longest pipe run from the point of delivery to the most remote outlet shall be determined using the longest run of piping and the load of the section.
(2) The pipe size of each section of branch piping not previously sized shall be determined using the length of piping from the point of delivery to the most remote outlet in each branch and the load of the section. [NFPA 54:6.1.2]
1215.1.3 Hybrid Pressure. The pipe size for each section of higher pressure gas piping shall be determined using the longest length of piping from the point of delivery to the most remote line pressure regulator. The pipe size from the line pressure regulator to each outlet shall be determined using the length of piping from the regulator to the most remote outlet served by the regulator.
[NFPA 54:6.1.3] 1215.2 Sizing of Gas Piping Systems. Sizing of piping systems shall be in accordance with Section 1215.2.1 for natural gas piping systems and Section 1215.2.2 for propane piping systems. 1215.2.1 Natural Gas Piping Systems. Table 1215.2(1) through Table 1215.2(23) shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for piping materials other than non-corrugated stainless steel tubing. Section 1215.3 shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for non-corrugated stainless steel tubing.
[NFPA 54:6.2.1, 6.2.2] 1215.2.2 Propane Piping Systems. Table 1215.2(24) through Table 1215.2(36) shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for piping materials other than non-corrugated stainless steel tubing. Section 1215.3 shall be used in conjunction with one of the methods described in Section 1215.1.1 through Section 1215.1.3 for non-corrugated stainless steel tubing.
[NFPA 54:6.3.1, 6.3.2] 1215.3 Sizing Equations. The inside diameter of smooth wall pipe or tubing shall be determined by Equation 1215.3(1), Equation 1215.3(2) and Table 1215.3 using the equivalent pipe length determined by the methods in Section 1215.1.1 through Section 1215.1.3. [NFPA 54:6.4]
LOW-PRESSURE GAS FORMULA (LESS THAN 1.5 psi)
[NFPA 54:6.4.1]
[Equation 1215.3(1)]
Q [0.381] D =
0.206
19.17 [(]
Δ H
)Cr x L
Where:
D = inside diameter of pipe, inches
Q = input rate appliance(s), cubic feet per hour at 60 ˚ F and 30 inch mercury column
L = equivalent length of pipe, feet
Frequently asked questions
How do I pick a method or table to size gas piping?
Start by totaling appliance inputs (use Table 1208.3.1 if manufacturer ratings are unavailable), convert to volumetric flow, then choose a CPC sizing method: Longest Length, Branch Length, or Hybrid Pressure. For most installations use the material‑specific tables in the Table 1215.2 series; use Equation 1215.3 when sizing smooth‑wall tubing or when required by the table notes. See §1208.3.2 and §1215.1–§1215.3 for the procedures and table selection guidance .
What is the minimum gas outlet size required by the CPC?
The CPC requires a supply piping outlet for a gas appliance to be not less than 1/2 inch in diameter, and not less than 3/4 inch for a mobile home outlet, as stated in §1214.4 .
When must I use engineering methods or the sizing equations instead of the tables?
Use the CPC sizing equations or full engineering design when conditions are outside the tables’ ranges (longer runs, higher total demand, nonstandard delivery pressures, or special materials). The code requires engineering methods acceptable to the authority having jurisdiction for those cases, and provides Equation 1215.3 and related guidance for smooth‑walled tubing and other situations (§1215.3 and §1215.5–§1215.6) .
More in California Plumbing Code
- Administration
- Definitions
- General Regulations
- Plumbing Fixtures and Fixture Fittings
- Water Heaters
- Water Supply and Distribution
- Sanitary Drainage (Drain, Waste, and Vent)
- Indirect Wastes
- Vents
- Traps and Interceptors
- Storm Drainage
- Fuel Gas Piping
- Health Care Facilities — Medical Gas and Medical Vacuum Systems
- Alternate Water Sources and Nonpotable Rainwater Catchment Systems
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