Installation Guide

11
3.2 Reference Data for Proper Sizing
3.3 Sizing Methods and Examples
Low Pressure (Less than or equal to 2.0 PSI Natural Gas)
In this scenario, an underground polyethylene gas line is being ran from the low pressure
outlet of the meter to a detached garage, outbuilding, or appliance that requires a natural
gas outlet.
Figure 3.1 2 PSI Natural Gas Supply from House to Garage
Step 1 Call 811 at least 3 days prior to digging to have any underground utilities marked prior
to digging.
Step 2 Determine length of gas piping from connection point at meter outlet to riser outlet
at the out building or appliance. Include the distance required to connect the riser to the gas
piping system near the meter. This connection must be made using rigid pipe or CSST that is
at least the same size as the PE pipe size.
Step 3 Determine the number and type of HOME-FLEX Underground® ttings that are
required in the system. Add the equivalent number of feet from Table 5.1 “Length to Add to
Each Run for Each Fitting” on page 21 of this guide to the number of feet calculated above.
Step 4 Determine the appropriate sizing table in Chapter 5 based on meter outlet pressure
and allowable pressure drop. For example, Table 5.2 on page 22 can be used for low pres-
sure with a pressure drop of 0.3" w.c. Find the nearest length that is equal to or greater than
the length calculated in step 3 above. Follow the row across until the number of BTU’s pro-
vided is equal to or greater than the required BTU’s required for this run- check the column
header for required pipe diameter.
Low Pressure (Less than or equal to 2.0 PSI) LP Gas
In this scenario, an underground polyethylene gas line is being run from the outlet of the
second-stage regulator to a detached garage, outbuilding, or appliance that requires an LP
gas outlet.
Table 3.1 Pressure Conversion Factors
¼ PSI = 6.921 in. w.c. (appox. 7 in. w.c.)
½ PSI = 13.842 in. w.c. (appox. 14 in. w.c.)
1 PSI = 27.684 in. w.c. (appox. 28 in. w.c.)
2 PSI = 55.368 in. w.c. (appox. 56 in. w.c.)
5 PSI = 138.42 in. w.c. (appox. 40 in. w.c.)
Table 3.2 Fuel Gas Information
Gas Type BTU per Cubic Foot Specic Gravity
Natural
Gas
1000 0.6
LP Gas 2516 1.52
Note: To determine the CFH of Natural Gas,
divide BTU load by 1000. To determine CFH
of LP, divide the BTU load by 2516.