Example Determining Pipe Size for Natural Gas

Example: Determining Pipe Size for Natural Gas

A generator has a 16Hp engine 60 feet from the supply. Determine the supply pipe size for Natural Gas fuel.

16 x 10,000 = 160,000 BTU’s / per hour for proper operation.

160, 000 + 146 cubic feet per hour. 1, 096

From Table 3-6, a 60 foot run requires a minimum 1” pipe at full engine load.

Natural Gas Connections

The incoming pressure must be 11 inches water column (6 oz. pressure).

Table 3-5 Natural Gas Flow Rate (Cubic Feet per Hour) per Pipe Length

Pipe						Iron Pipe Size
Length
Length	1/2″	3/4″	1″	1–1/4″	1–1/2″		2″	2–1/2″	3″	4″	6″	8″
(Feet)	1/2″	3/4″	1″	1–1/4″	1–1/2″		2″	2–1/2″	3″	4″	6″	8″
15	73	165	332	722	1174		2386	3704	6253	13352	37229
30	50	115	232	515	818		1712	2646	4521	9331	26330	53728
45	41	95	191	418	673		1419	2213	3752	7600	22462	43867
60	37	83	166	366	587		1241	1924	3319	6542	18595	37999
75		74	149	332	524		1077	1684	2886	5772	16652	33959
90		67	137	298	433		962	1501	2597	5291	15200	31025
105		63	126	274			885	1376	2357	4906	14064	28715
120			115	260	404		827	1289	2213	4618	13160	26859
150			105	233	366		750	1174	2011	4185	11775	24050
180			96	216	337		693	1077	1876	3848	10736	21934
210			89	197	308		635	991	1712	3559	9937	20298
240				183	289		596	933	1616	3357	9235	18990
270				171	274		558	875	1520	3127	8658	17903
300				164	260		524	827	1433	2886	8177	16998

Note: Almost all operation problems are related to the installation techniques used. Do Not guess, be sure pipe size is adequate for required flow rate.

1.Connect the proper size gas pipe at the Inlet Connection to the Fuel Lock Solenoid. Connect the Natural Gas pipe line shown in Figure 3-3 using the correct size pipe for the required flow rate and length of pipe. Refer to Table 3-5 for pipe size. Be certain that all connections are sealed and no leaks are present. The installer must ensure that all gas connections comply with all building codes.

2.Verify Fuel Supply Pressure

Prior to initial operation of generator, verify that fuel system pressure is 11″ Water Column (6 oz. pressure) and fuel pipe sizes comply with Table 3-5.

3.Proceed to Electrical Connections.

Figure 3-3 Gas Line Connections

Air Cleaner

Carburetor

Solenoid, Fuel Lock

Inlet Connection

Mounting Bracket

External Supply Piping (by installer)

U.L. requires a second shutoff valve and regulator to be installed in the supply piping to control the gas supply to the generator.

To Inlet	Supply Piping
To Inlet
Connection
Additional Regulator	Additional Valve
(11 - 14" water column pressure)	(Safety Shutoff Valve)

MN2408

Receiving & Installation 3-7