pipe sizing

Brad White_68

but at least here in Massachusetts, you cannot run gas pressure over 14 inches (1/2 PSIG roughly) without a special permit. And damned if the gas company guarantees any pressure over 4 inches anyway. Your location may vary. Void where prohibited :)

Jim Burke comfort zone

gas pipe sizing help

Hey guy's & ladies need to locate pipe sizing chart .
I have a run of 600 ft. of pipe going to 250000 btu furnace but can't find my chart to find proper pipe size .
Thank you to all that reply.

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Brad White_68

Assumed Pressure Drop?

Jim, Hi

If you take an assumed total pressure drop of 0.20 inches WG and if your 600 feet is developed equivalent length, you are looking at a 2-inch IPS.

It actually falls between a 1.5 and 2 inch size. 2-inch will handle 300 MBH at that load, length and pressure drop.

If I take the 2-inch size and 250 MBH gas load, the total developed length (including fittings of course) can be as much as 900 feet, just so you know your outside range.

Hope this helps.
If your gas company requires a different total pressure drop, let me know.

Brad

Unknown

that whole lotta

I was in the same situation couple years ago. Had my engineer figured the pipes size using the higher incoming gas pressure, using the 1 1/4 pipe instead of 2 inches, using step down regulator before the boiler..

Unknown

intresting..

Thanks Brad, here in chicago suburb, gas co. just told me incoming pressure at main manifold is 2 psi and I had to work from that... Its was an old window factory and tenents that time wanted their own meter for each heating units... Guess its one way of goverment to keep their jobs by making these rules..

Brad White_9

Our gas pressure limitation

as far as guaranteed minimum pressure is (as I understand it) based on the fact that many of the local service mains were originally for gas lighting and the occasional suicide I suppose.

The mains are 100+ year old wrought (or rotten!) iron so anything over 12 inches is unlikely. They guarantee 4 inches WC just to be safe in the dead of winter when draw is the highest.

(Wonder if they grasp that low pressure gas moves faster than high pressure gas?? Mmmmmm. )

The prohibition or limitation on pressure indoors has to be something akin to anything "high pressure" as a relative term. In NYC I understand, you cannot run any steam over 15 psig in a building without some special provisions. Then again, to the crank it down crowd, why would you want to?


Regards,

Brad

Empire_2

Brad

That's exactly what I got on my National fuel slide rule. I usually design to .5 max. press loss. Nat fuel Say's .3

Mike T.

Brad White_9

My circular slide rule

is from Boston Gas (Now Keyspan) and they "arrowed" the 0.2" WC index line. I guess it underscores that all sizing is local. All the more reason to state the parameters, right, wrong or indifferent.

I can see how this makes sense; maximum available pressures do vary even here in Boston. Sometimes you are near a high pressure line; still the LP side uses the same total pressure drop.