# Commercial Propane Gas Design



## 2XP (6 mo ago)

Hi guys,

I'm new here and though I could join everyone. I'm a Mechanical Engineer working on a commercial laundromat and had a few questions regarding the gas system.

It will be on propane and 2 stage regulators. First one at the tank and second one outside the building. I'm struggling to figure out which code chart to use to size the gas piping. I have calculated 3,400,000 BTUH of required gas. If I want to use the longest length method, do I count the length from the second regulator or all the way from the propane tank? Or do I size the line from the 1st regulator to 2nd regulator based on that length and 10 PSI chart and then from the 2nd regulator to appliance length based on another chart?

The dryers the owner picked require an inlet pressure of 11" WC. I looked at using TABLE 402.4(28) SCHEDULE 40 METALLIC PIPE from the Florida Building Code, but that chart is for
an inlet pressure of 11" WC with 0.5" WC pressure drop.

Further down in the code, it mentions -

*402.6 Allowable pressure drop.*
The design pressure loss in any piping system under maximum probable flow conditions, from the point of delivery to the inlet connection of the appliance, shall be such that the supply pressure at the appliance is greater than or equal to the minimum pressure required by the appliance.

With the pressure drop, does this mean I have to use the 2PSI chart to size the piping? 

Any insight will be helpful. Thanks in advance for any help.


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## dhal22 (Jul 30, 2010)

I request 100-400 psi meter then I don't have to worry about volume. Just regulate everything


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## Plumbus (Aug 4, 2008)

I would like to discuss this. If you are a plumbing engineer, which I would assume you would be if you are designing a gas system, then I doubt you would be challenged by our intro requirement. It's your move. 2XP.


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## Plumbus (Aug 4, 2008)

Being from California, I can't speak for any familiarity with the IPC. However, the physics of pipe loads is universal.
Your second option is the correction one. BTU capacity is a function of pressure, pipe size and length of run.
The tables in your code book should direct you to your answer. 
Note: Table volumes are given in cubic feet per hour. To calculate energy delivery close to the bone, refer to your propane supplier for accurate conversion from CFH to BTUs.


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