Natural gas “pressure drop” explanation & CSST

[Robert McNeil]

Hello all,

I wondered if someone could explain pressure drop in terms of sizing lines for natural gas. Ive received some mixed info. Am wanting to run CSST to a range that has 44,700 BTUs for the burners and up to 14000 BTUs on bake. My inlet pressure is 6” water column and the line will be just under 50’ from the meter. My range says it needs 4”wc and has a regulator built in. Looking at the charts for Sizing, you have the option for 0.5” wc and so on. It seems like most people recommend using the 0.5”wc pressure drop chart. If I use that chart I would need to run 3/4” CSSt, but if it were any of the others 1/2” csst looks like it would be ok.

 

[wwhitney]

You raise an interesting point.

Standard practice for 7" w.c. systems is to design for 0.5" w.c. maximum pressure drop. Yet when I checked the IFGC, the only limitation on pressure drop I find is that under maximum probable flow conditions, each appliance be supplied at a pressure not less than the appliance's minimum pressure. Which would give you a lot more leeway.

https://up.codes/viewer/washington/ifgc-2015/chapter/4/gas-piping-installations#402.5

Nonetheless, it seems prudent to me to go with the larger size.

Cheers, Wayne

 

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[Jeff H Young]

probably work fine with 1/2 but old school UPC code was 3/4 min to a range and a range to me is a fixture people might change out with one that needs more. 65000 BTU was standard demand on a house range . So I think 3/4 would be adequate and a good choice . that flexy stuff is easy to run and 50 foot of 3/4 shouldn't break the bank, and isn't way oversize. I'm not going to tell you to run 1 inch though 3/4 is perfect