Installation Guide

HOME-FLEX Underground 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
TM
Underground fittings 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 20 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 21 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 Specific 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.