Natural gas pipe sizing upstream of a pressure regulator
Natural gas pipe sizing upstream of a pressure regulator
(OP)
I'm looking for some advice on sizing natural gas piping for some boilers. I'm wondering if the method I have been using for years is too conservative.
I have 2 psig gas available and will be running 100 TEL feet through the building to a boiler room. The boilers only need 15"WC of pressure, so I will have a regulator to step it down. My gas tables for 2 psig gas are based on a 10% pressure drop. Using those tables with my 100' and total load of 6,600 CFH, I need a 3" pipe.
It occurred to me however, that I might not have to limit my pressure drop to only 10%. Since I'm reducing the pressure anyway, why not allow a much larger pressure drop in the line before it hits the pressure regulator? Am I missing something obvious here? Are there velocity or noise concerns? Or will the gas regulator not respond well if it sees varying inlet pressures as boilers cycle? If none of these are a concern, I'm sure I could drop my pipe to 2-1/2" or maybe even 2".
Any thoughts?
I have 2 psig gas available and will be running 100 TEL feet through the building to a boiler room. The boilers only need 15"WC of pressure, so I will have a regulator to step it down. My gas tables for 2 psig gas are based on a 10% pressure drop. Using those tables with my 100' and total load of 6,600 CFH, I need a 3" pipe.
It occurred to me however, that I might not have to limit my pressure drop to only 10%. Since I'm reducing the pressure anyway, why not allow a much larger pressure drop in the line before it hits the pressure regulator? Am I missing something obvious here? Are there velocity or noise concerns? Or will the gas regulator not respond well if it sees varying inlet pressures as boilers cycle? If none of these are a concern, I'm sure I could drop my pipe to 2-1/2" or maybe even 2".
Any thoughts?





RE: Natural gas pipe sizing upstream of a pressure regulator
David Simpson, PE
MuleShoe Engineering
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