Do I have enough gas, coming from meter

Sew- kul

I have 1 inch supply coming from my meter. Do I have enough gas to handle 384,000 btu of appliances. Closest appliance 10 ft. 199,000btu. furthest is 50ft. 150,000 btu. or do I have to run 1 1/4 . Supply has 2-90's and is straight 35ft. run. Thanks for your input... Ken

Tim McElwain

First is the meter large

enough to handle 384,000 BTU's?



A Schedule 40 black pipe system with a .3" W.C. allowable pressure drop



1" 50 feet will handle 215,000

!" 30 feet will handle 284,000



1 1/4" 50 feet will handle 442,000

1 1/4" 30 feet will handle 583,000

Sew- kul

enough gas

Is upsizing the piping from the meter to 1.25 inches enough or do I need to call gas company to see what's at the meter. Thanks in advance. Ken

Rich_49

Allowable Pressure Drop

Tim,  I believe you are using a .3" chart . Is that Correct?  Allowable Pressure drop as defined in 402.5 in the IFGC is                                                                                           "the design pressure loss in any piping system under maximum probable flow conditions from the point of delivery"(meter)"to the inlet of the equipment shall be such that the supply pressure at the equipment is greater than the minimum supply pressure required for proper equipment operation. "

 Taking this approach , the installed system may in fact be large enough . Sew-kul , what is the range in inches water column stamped on the regulator prior to the meter . 5-6"  ,  6-8" ? 

Rich_49

Tim

I do not mean to challenge you . But you are well respected in the industry and maybe we should really start to educate the installers / designers . After all the intent of the code is to minimize the hazards associated with the storage and distribution of explosive gasses within the built environment , is it not ?    In the example given by the Op .   384,000 with the first being 10 feet in and 199,000 the pressure loss through that segment of the system would be .18" wc , assuming an 8" reg with a 1/2" drop through the meter we would have 7.32" at the tee , the segment from the tee to the equipment could be 33.13 feet of 1/2" (@.067" pdpf) and still supply with all fixtures calling . The second segment according to our poster would be 185,000 . 190,000 would have a pressure drop of .005" per foot for steel pipe . 7.32" minus 5.1 inches would give us an allowable pressure drop of 2.25" . 2.25" divided by .005" would allow us to go 450 feet to the remaining 185,000 .  Is this not correct ?

  I am only speaking in terms of what we can do , here in NJ the utilities would love to see us only use a .5" pressure drop and the longest run method , but should we ?  We are allowed to utilize any of the sizing methods at our disposal , maybe not so everywhere . But from a physics standpoint barring the complete lack of physics in an area the sizing methods should be utilized to design the best system . It would be a shame for someone with an installed system that is in fact adequate to spend time and money to upgrade or change for reasons that do not exist .  What say you ? 

Tim McElwain

Send me a piping

plan of what you have my e-mail gastc@cox.net.



Have the utility determine if the meter is sized correctly.



Find out what pressure the utility will guarantee you. In some areas it is only 5" W.C.



How do you want to pipe this Longest Run Method, Branch Method let me know.

Tim McElwain

Rich I was not trying

to size his piping for him just showing him some options based on what his total load is. Yes I used allowable loss of .3 which is what the utility up here recommends due to pressure problems in some areas.



We also do not know if this a high pressure area or a low pressure area we are talking about.

Rich_49

Understood

that Tim . You can surely see where your response may elicit him to doubt the installed piping's effectiveness though ?  Correct , we do not know what type of pressure he is receiving , thus the advice to observe the regulator information  .   I am fortunate to be in an area where such pressure problems do not exist , it is a luxury .  Tim , what are your thoughts on those same problems being lessened by educating as to sizing the installed systems in this way ?

 

Tim McElwain

The allowable loss

listed in the codes does not have to be deducted from pressure it is a factor already built into the numbers in the tables. That is why the different tables and different values. Pipe sizing is based on those tables and the measured distance to each appliance. It is not based on supplied fuel to the structure as that could be 100 lbs pressure reduced to 6" W.C. (typical on most residential regulators). That versus the issue in most major cities in the northeast of an inner city cast iron system low pressure less than 1/2 a pound of pressure (14" W.C.). Those low pressure area are critical both to piping into the dwelling and also piping in the building. When I was with the utility I set a rule for all gas heating systems using a minimum 1" for piping. This was designed to overcome the winter time issues to some degree of low pressures in the mains, sometimes as low as 4" W.C.

Tim McElwain

Rich don't make it any more complicated

than it already is. Just use the tables, find out what you local utility suggests for allowable loss and follow all the steps outlined in the codes for pipe sizing including maximum demand, diversified loads etc.



Each contractor has to look at his or her particular situation as to what method they use.

Tim McElwain

In all my classes for licensing

we spend considerable time on pipe sizing, pressure problems, carbon monoxide, gas safety, air for combustion, vent sizing etc. These are all things that are very much lacking in most trades training programs.



A very well know plumbing and heating contractor recently made a statement that when he went to a customers home and stepped inside he smelled a strong odor of gas. His immediate response to the customer was that his first priority was to "find that leak". I beg to differ his first responsibility to his customer and himself was to evacuate the premises and call the gas company. Even if he has a test instrument to measure level of gas there is a protocol which must be followed. These things are not taught in most trade schools the way they should be.