Cant get my head around pressure drops on different meters.

[Readingplumber]

Hi can some one please give a simple explanation to why on existing installations -

on E6 meters you are allowed 8mb drops and U6 you are allowed 4mb.

I just dont get the logic - because if the e6 is a lot smaller meter with less gas in it and you are allowed more of a drop?

Thanks

 

[oldplumber]

youve probably answered your own question if you just think about what you said

 

[Dannypipe]

Because the E6 meters are smaller, if you lose the same amount of gas as in the larger U6, it will show more on your U guage. The same gas lost, has more of an impact as the total volume is less. Hope that makes sense.

 

[markinaark]

consider them as cans of coke, if you lost half your can it would be a large drop. if you had a 10 ltr bottle of coke and lost the same aqmount . it would show up as a smaller drop

 

[Dannypipe]

Nice....that's what I was trying to describe...and failed!!

 

[REDSAW]

consider them as cans of coke, if you lost half your can it would be a large drop. if you had a 10 ltr bottle of coke and lost the same aqmount . it would show up as a smaller drop

take this one as a good example,
but shake the coke for ten minuites first, then the result will be more apparent.
0.01 v 0.0357

 

[GrahamM]

This is a bit easier to get head round.

Take a standard U6/G4 attach manometer before the inlet and a manometer after the outlet. If you have 20mbar going in you will expect in region of 16mbar coming out.

The mechanical nature of the meter bellows basically absorbs 4mbar right away. The E6 has no mechanics inside and you will get little or no change between inlet and outlet.

 

[Puddle]

I would just like to point out that ukplumbingforum is not connected to or in anyway endorse coke and there are other brands of pop on the market,that you can do these tests with equally as well

 

[Rodreguez]

i was told u6/g4 had a diaphragm in so less drop is allowed

 

[migoplumber]

i like pepsi, or fanta.

 

[Billy Bob Bob]

I would just like to point out that ukplumbingforum is not connected to or in anyway endorse coke and there are other brands of pop on the market,that you can do these tests with equally as well

but do not use beer under any circumstances that would be wasteful and not environmentaly friendly

 

[plumbster3456]

but do not use beer under any circumstances that would be wasteful and not environmentaly friendly

I like this answer the best well said gas man.... please under no circumstances use good quality beer

 

[gbgas001]

As everyone says it is true its the volume in the meter AND IN THE INSTALLATION and the diapragms that are in there too, But the point that is mainly missing is .... its all about an Emergency and how quick the drop will stop when the gas is isolated... the bigger the meter the less the drop allowed because more gas can be pushed out...

E6.... 8MB with pipe up to 28mm
E6.... 4.5MB with pipe greater than 28mm but up to 35mm
U6/G4.... 4MB with pipe up to 28mm
U6/G4.... 2.5MB with pipe greater than 28mm but up to 35mm
U16.... 1MB with pipe up to 28mm
U16.... 1MB with pipe greater than 28mm but up to 35mm

AND if you testing an installation without a meter such as a flat with a secondary emergency control valve... its the same as having an E6 meter.

of course the standards have you captured there must be no drop in the pipework new or old so the drop must really be at the appliance.... there must be no smell of gas. The chances of you not smelling gas at the appliance will be small unless its going straight into the flue.

AND WOULD ANY ONE HERE LEAVE A 2MB DROP LET ALONE AN 8MB DROP

Regards
gb-gas

 

[Bernie2]

You also get more drop on small pipes than big ones!!

The reason being is that more of the gas stream in a small pipe is touching the walls of the pipe than it is in a big pipe.

So even if both meters had the same mechanics the smaller would still register a greater drop than the bigger!!

Have a look at Bernoulli's principle there is a good animation on the web knocking about somewhere.

 

[Jnamond]

The u6 and g4 actually hold gas while the e6 does not