gas pipe size

Unknown

can give you what they use. I usually use .3 for natural gas and .5 for LP gas.

What charts are you using from what source?

curiousity kills

gas pipe size

When refering to the gas pipe size chart for nat gas do you go by .3 IWC or .5 IWC pressure drop and why.Also on LP they only give you .5 IWC drop...????? Thanks for any help.

curiousity kills

I was refering to table 9.1 9.2 in the NATIONALFUEL GAS CODE BOOK. If your sizing a job one chart your ok but the other chart might require bigger pipe.

Unknown

What year code

book are you using? The 2002 edition has pipe sizing tables as 12.1, 12.2 etc. The new code book has many options for sizing depending on the system.

You are using the 1999 code book it seems.

Chart 9.1 is for natural gas at less than .5" WC pressure (14" WC) at allowable loss of .3"

The only difference with chart 9.2 is the allowable loss which is .5"WC.

Allowable loss is a factor which allows for different sizing.

Example a 1" pipe 40 feet long in chart 9.1 will allow only 245,000 BTUs

While a 1" pipe on chart 9.2 at 40 feet will allow 320,000 BTU's.

Does that answer your question?

Dale

.3 and .5

What this means is if the utility gives you 7 inches WC gas out of the meter using this pipe table with all load on at the end of the longest run you still have 7 inches minus .3 inches or 6.7 inches pressure in front of you longest run gas valve. Almost all nat gas will work with 4" supplied. If you look at the .5 table you will see smaller pipe for the same load and longest run. There you have 6.5 inches gas pressure left at the end. The .3 table is the old one for low pressure mains like real old cities still have. I use the .3 table unless the .5 gives me a smaller size, like I never use 1 1/4 pipe if the .5 table gives me 1" pipe.

curiousity kills

gas pipe

Thanks for the replies.Tim I was using the 99 book.Also The same chart is in my boca plumbing book.We do not do new construction just service. So most of what we do is adding new gas stove installs or fireplace inserts.If I am looking at an existing system to add to it, it may be maxed with the .3 drop chart but ok with the .5 drop chart.Are you then saying in this situation to call the utility co. for the correct drop to read?

Unknown

That is correct

if you read Dales post who works for a utility that will explain how they look at it.

The utility I worked for used .3 all the time which is what most of them do as many of the older companies still have low pressure systems.

You do have to be careful with some of the new high end stuff that wants a definite 6" WC at the inlet to equipment with no drop in pressure.

curiousity kills

Thanks for responding.....