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

## nat gas pressure drop arguement

### 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?

### Re: nat gas pressure drop arguement

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.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

Pipe flow calculations - since 2000

### Re: nat gas pressure drop arguement

You could be very right but again depending on flow velocity. For higher velocities it is a problem, for low one it isn't.gasguy wrote: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?

Pipe flow calculations - since 2000