28
LP-542 REV. 7.16.15
A. ADDITIONAL PRECAUTION FOR EXCESS FLOW VALVE (EFV)
If an excess flow valve (EFV) is in the gas line, check the manufacturer’s minimum and
maximum flow capacity ratings. An improperly sized EFV will not allow for a full flow of
gas to the boiler and will cause the boiler to malfunction.
B. GAS PIPE SIZING TABLES
1. Gas Pipe Sizing
This information is for reference use only. Refer to gas pipe manufacturer specifications
for actual delivery capacity. The DOE standard for Natural Gas is 1100 BTU/ft
3
. Contact
the local gas supplier for actual BTU/ft
3
rating.
2. Natural Gas Pipe Sizing
The following tables list maximum capacity of pipe in cubic feet of gas per hour for gas
pressures of 0.5 psi or less and a pressure drop of 0.5 inches water column, based on a
0.60 specific gravity for natural gas.
Maximum Natural Gas Delivery Capacity – Length of Corrugated Stainless Steel Pipe in Feet
Cubic Feet per Hour (0.60 Specific Gravity, 0.5 WC Pressure Drop)
Table 11 – Natural Gas Delivery Capacity – Corrugated Stainless Steel Pipe – Refer to ANSI Z223.1 – National Fuel Gas Code,
Latest Edition
Maximum Natural Gas Delivery Capacity – Length of Black Iron Pipe (Sch. 40 Metallic) in Feet
Cubic Feet per Hour (0.60 Specific Gravity, 0.5 WC Pressure Drop)
Table 12 – Natural Gas Delivery Capacity – Black Iron Pipe – Refer to ANSI Z223.1 – National Fuel Gas Code, Latest Edition
3. LP (Liquid Propane) Gas Pipe Sizing
The following is intended for use for piping between a Single or Second Stage (Low Pressure) Regulator and the boiler. The following
tables list maximum capacity of pipe in cubic feet of gas per hour for an inlet pressure of 11 inches water column and specific pressure
drop of 0.5 inches water column based on 1.5 specific gravity for liquid propane.
Maximum Liquid Propane Delivery Capacity – Length of Corrugated Stainless Steel Pipe in Feet
Cubic Feet per Hour (0.60 Specific Gravity, 0.5 WC Pressure Drop)
Table 13 – Liquid Propane Delivery Capacity – Corrugated Stainless Steel Pipe – Refer to ANSI Z223.1 – National Fuel Gas
Code, Latest Edition
Maximum Liquid Propane Delivery Capacity – Length of Black Iron Pipe (Sch. 40 Metallic) in Feet
Cubic Feet per Hour (0.60 Specific Gravity, 0.5 WC Pressure Drop)
Table 14 – Liquid Propane Delivery Capacity – Black Iron Pipe – Refer to ANSI Z223.1 – National Fuel Gas Code, Latest Edition
Figure 15 – Excess Flow Valve (EFV)