gas piping

[rmusa]

Attached is gas piping diagram.
IFGC 2015

Total load of 1170 CFH, see attached roof plan and riser. Furthest RTU is 200' from the meter. Lengths of the branches on dwg

How do we determine which chart to use 402.4---(1) , (2) or (3). If we can reduce the gas pressure to any of these charts then are we allowed to use any or smallest pipe possible or is there a code requirement.

Standard equipment, RTU's and a gas fired heater.

Adjacent suite is similar. Their load is 760 MBH, with 5 RTU's and two water heaters.

Their meter reads 630 CFH at 1/2" diff, 1320 CFH at 2" diff. MAOP 25 psi, main is sized at 3" and furthest equipment is 150'

Incoming main is 1-1/2"

If sized using chart 402.4(2), will this work?

 

[PEDARRIN2]

If you do not have experience using the code, you should first try to get help from more experienced engineers/designers in your company. This forum is good, but should not be a substitute for good mentoring.

The charts are used for whatever pressure drop (dp) you design for the assistance. Common practice is the pressure drop should not be more than 20% of the total pressure.

The design approaches are indicated in Appendix A of the code. Read it, learn it, know it.

Based upon indicated pressure being <2 psig and dp is 0.5" w.c., you would use 402.4-(2). Based on 920 MBH (per detail) total load, and 200 feet of pipe, a 2.5" starting pipe size would be appropriate. If load is 1170. then a 3" pipe is required to start. This is assuming 50% fitting/valve equivalent length factor so use the 300 ft pipe row. As load drops, read horizontally to the left of the 300 foot row to determine reducing pipe sizes.

 

[dbill74]

Adding to what Pedarrin2 said.
The appliances will have a minimum required supply pressure in order to function properly. You need to ensure that the furthest fixture has sufficient pressure. They also have internal regulators to get the exact pressure they need so extra pressure at the closer appliances is not too much of a concern. With a 20% drop, you should have acceptable pressures at all the appliances.