## nat gas pressure drop arguement

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gasguy
Posts:2
Joined:Thu Feb 27, 2014 12:51 am
nat gas pressure drop arguement
hi folks. can someone of higher intelligence than me please settle this argument between my friend and I.
I say that. if you had for example a one inch gas pipe for 10 meters, then reduced to half inch for 2 meters and then increased back to one inch for a further 10 meters,, that there would be a working pressure drop across the pipeline from start to finish the SAME as if the pipe was one inch for 10 meters, then reduced to half inch for 12 meters.

he maintains that the pressure drop would be less across the system in the example where the reduction in pipe size was in the centre as there was an increase back up to one inch for the final ten meters.

please settle this once and for all!!!
thanks

gasguy
Posts:2
Joined:Thu Feb 27, 2014 12:51 am

### Re: nat gas pressure drop arguement

or if I used another example where the meter outlet connection was 3/4inch pipe, but the pipework required was worked out to be 1 1/4 inch, wouldn't the 3/4 inch outlet cause a huge pressure drop? and if you were only allow to have a working pressure drop of 1 millibar from meter to appliance, you couldn't achieve it without changing the size of the meter outlet?

Posts:373
Joined:Mon Feb 08, 2010 7:47 pm

### Re: nat gas pressure drop arguement

gasguy wrote:hi folks. can someone of higher intelligence than me please settle this argument between my friend and I.
I say that. if you had for example a one inch gas pipe for 10 meters, then reduced to half inch for 2 meters and then increased back to one inch for a further 10 meters,, that there would be a working pressure drop across the pipeline from start to finish the SAME as if the pipe was one inch for 10 meters, then reduced to half inch for 12 meters.

he maintains that the pressure drop would be less across the system in the example where the reduction in pipe size was in the centre as there was an increase back up to one inch for the final ten meters.

please settle this once and for all!!!
thanks
I think that pressure drop will never be the same. You can have many variations depending on flow velocity and fluid viscosty. And I think that in most cases second one will have higher pressure drop, considerebly.
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