LP gas pipe capacity question

[Mike Baker]

I have 50 feet of 1/2" IPS pipe connected to 50 feet of 3/4" IPS pipe going to the regulator outside. There are 3 1/2" elbows and one tee. There are 3 3/4" elbows. The tees are at the bottom of a vertical segment for a trap. There is one 3/4 x 1/2 reducer tee. There are no branches to any other appliances.
Will this feed a 100,000 btu propane heater properly? There are no branches to any other appliances.

 

[CountryBumkin]

See http://www2.iccsafe.org/states/seattle/seattle_fuelgas/PDFs_fuelgas/Appendix A.pdf

I hope this helps. Good luck.

 

[Sponsor]

 

[Mike Baker]

See http://www2.iccsafe.org/states/seattle/seattle_fuelgas/PDFs_fuelgas/Appendix A.pdf

I hope this helps. Good luck.

Whee Hew. I am not a math wizard engineer and I cant do all of those formulae.

According to http://inspectapedia.com/plumbing/LP_Gas_Line_Sizing_LPGE_Co.pdf
50 ft of 1/2 " sched 40 pipe will deliver 1398,000 btu @ 10 psi inlet with a 1 psi pressure drop.
50 ft of 3/4 " sched 40 pipe will deliver 2923.000 btu @ 10 psi inlet with a 1 psi pressure drop.

I cant figure out how to combine the two unless I can see a chart for how much pressure drop there is per ft of pipe and for each fitting for both sizes of pipe.

I believe my Reznor UDAP100 LP heater requires 10 PSI at the inlet and most two stage regulators put out 11 PSI

What I have is a two stage system with 50' of tubing from the first stage regulator at the tank to the second stage regulator. and 50 ft of 1/2" pipe coming from the second stage to the heater. I want to do away with the second stage regulator by replacing the tubing with 3/4 IPS pipe and installing a standard 2 stage regulator at the tank. I really don't like flimsy delicate tubing but I like running iron pipe. There is just something solid and dependable about it. The 50 ft lengths are just gross estimations and it is probably closer to 40 feet for both sizes but I just want to be sure. If it gets too close to call I will measure it exactly.

Mike

 

[hj]

1. You do NOT have 10 psi service pressure. You would have 6 INCHES of pressure., if it were natural gas system
2. You do NOT calculate with a 1 psi pressure drop. You calculate for 1 inch pressure drop
3. You have an LPG system which operates at about 11 INCHES of pressure so a natural gas table will not do you any good.

 

[Mike Baker]

1. You do NOT have 10 psi service pressure. You would have 6 INCHES of pressure., if it were natural gas system
2. You do NOT calculate with a 1 psi pressure drop. You calculate for 1 inch pressure drop
3. You have an LPG system which operates at about 11 INCHES of pressure so a natural gas table will not do you any good.

I just dont understand this water column/psi thing. 1 psi=276" wc? 1" wc=0.397003 psi?
one chart uses 11" wc and the next uses 10 psig. I don't get it. Why do they keep switching back and forth?

I converted a Reznor UDAP from natural to LP and I checked the manifold pressure with my digital manometer and it was 10" wc, right on the money. But what I am asking is will 50' of 1/2" iron pipe joined 50' of 3/4" iron pipe deliver enough LP gas to a 100 mbtu heater? Is there a chart somewher that shows the pressure drop per foot and per fitting? I could calculate it with that.

 

[Reach4]

1 psi=276" wc?

No. 27.7076 inches.

1" wc=0.397003 psi?

No. 0.0360912 PSI.
http://www.kylesconverter.com/pressure/inches-of-water-to-pounds-per-square-inch

Inches of water is used for low fuel gas pressures. PSI is used for high pressures.

http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d_827.html
I don't have the rule of thumb numbers for converting a fitting to an equivalent number of feet.

Ask your propane supplier. I think you can get the propane to the house at a higher pressure and regulate it at the load. You can use much smaller pipe that way. Your local propane people should know the rules. I don't.

If there is a chance that natural gas will become available later, you could consider using piping that would be big enough for that, while you are running it.

 

[Mike Baker]

No. 27.7076 inches.

No. 0.0360912 PSI.
http://www.kylesconverter.com/pressure/inches-of-water-to-pounds-per-square-inch

Inches of water is used for low fuel gas pressures. PSI is used for high pressures.

http://www.engineeringtoolbox.com/propane-gas-pipe-sizing-d_827.html
I don't have the rule of thumb numbers for converting a fitting to an equivalent number of feet.

Ask your propane supplier. I think you can get the propane to the house at a higher pressure and regulate it at the load. You can use much smaller pipe that way. Your local propane people should know the rules. I don't.

If there is a chance that natural gas will become available later, you could consider using piping that would be big enough for that, while you are running it.

It does not seem like such a complicated question so let me start over.
I have a 100,000 BTU LP gas heater that is fed by 50 feet of 1/2" sch 40 pipe leading to the outside. The 1/2" pipe was fed with a second stage regulator outside and that regulator was fed with 50' of copper tubing clad in yellow connected to a first stage regulator at the tanks.

Someone removed the second stage regulator and the copper tubing. I would like to run 3/4" sch 40 pipe from the end of the 1/2" pipe to the tanks and hopefully eliminate the second stage regulator, having a standard 2 stage regulator at the tanks.

I have seen all those tables and charts but I cannot find one that tells me whether 50' of 3/4 pipe feeding 50' of 1/2" pipe will supply enough gas. If I measured the exact distances it would probably be closer to 40' of 3/4" + 40' of 1/2"