low gas inlet pressure? is this a major problem???
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Come on Joe tell us what size it should be and the associated drop.
Lets use 3m3/hr as an example over 10m.
What's its maximum length, what's it pressure drop over 10m
Now do the same with 28mm, what's its max length, what's it drop over 10m
Lets use 3m3/hr as an example over 10m.
What's its maximum length, what's it pressure drop over 10m
Now do the same with 28mm, what's its max length, what's it drop over 10m
So Joe are you telling me I can chuck out all my 22 and 28mm fittings and cutters because I can do it all in 15?
Should save me a few Bob.
Tell me again...what do you think is causing this pressure drop?
Should save me a few Bob.
Tell me again...what do you think is causing this pressure drop?
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Lee. l don't have the charts and calcs to do the maths. If I did your line of work then I would get them and learn how to use them.
However, I do have a good general grasp of how things work (which is why I'm hanging around in this forum - I'm a lifelong learner).
Dan, when it comes to pipe size then it's the Venturi effect that prevents small bore tubes being used unless at a much higher pressure.
If you had a 28mm pipe that reduced down to 22 - then 15 - then 10 then 8mm, then to get the same VOLUME of gas the gas would have to move at a much higher speed as it passed from section to section. This in turn means that the effect of friction rises as speed is increased and a loss of FLOW. It doesn't actually reduce the pressure at all. If you switched off a tap at the end of the 8mm section it would have the same PRESSURE as the reading at the meter.
However, I do have a good general grasp of how things work (which is why I'm hanging around in this forum - I'm a lifelong learner).
Dan, when it comes to pipe size then it's the Venturi effect that prevents small bore tubes being used unless at a much higher pressure.
If you had a 28mm pipe that reduced down to 22 - then 15 - then 10 then 8mm, then to get the same VOLUME of gas the gas would have to move at a much higher speed as it passed from section to section. This in turn means that the effect of friction rises as speed is increased and a loss of FLOW. It doesn't actually reduce the pressure at all. If you switched off a tap at the end of the 8mm section it would have the same PRESSURE as the reading at the meter.
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Seriously if you did even try the core domestic gas Cerys let alone all the commercial you see big part of the exams is pipe sizing, pipe work installation and other factors. Friction/resistance of pipe work and fittings is always taken into account.
Basically it does affect the pressure at appliances, you cannot force gas faster then gas main can provide. So size and length of runs and all fittings are accounted for.
For the op, guys lets get back on topic
Please go back to alarm forums joe
Basically it does affect the pressure at appliances, you cannot force gas faster then gas main can provide. So size and length of runs and all fittings are accounted for.
For the op, guys lets get back on topic
Please go back to alarm forums joe
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Which is what I've just said.
Not what you said here joe, all matters simple.
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Joe ill help you out
22mm Max run is 15m if using the table (ige/up/2)
10/15= 0.67mbar drop.
Ie meter would be 21 (perfect world) appliance would be 20.3bar note its not
28mm max run is 50m
10/50= 0.2mbar drop
Ie meter would be 21, appliance would be 20.8
It makes a massive differnce and your examples of voltage are not compatible.
I'm both instances there would be 3m/hr at the appliance.
Our rules are simple across the pipework for natural gas you can not have greater than a 1mbar drop.
This is basic's, as you don't know the basics maybe you should stop giving out gas safety advice.
22mm Max run is 15m if using the table (ige/up/2)
10/15= 0.67mbar drop.
Ie meter would be 21 (perfect world) appliance would be 20.3bar note its not
28mm max run is 50m
10/50= 0.2mbar drop
Ie meter would be 21, appliance would be 20.8
It makes a massive differnce and your examples of voltage are not compatible.
I'm both instances there would be 3m/hr at the appliance.
Our rules are simple across the pipework for natural gas you can not have greater than a 1mbar drop.
This is basic's, as you don't know the basics maybe you should stop giving out gas safety advice.
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I don't give out gas advice. Neither should you if you follow the forum rules.
So lets look at the OPs question then.
In your opinion will re-piping half of the pipe from the meter with 28mm and joining the existing 22mm make any difference? If so - how many mbar difference?
So lets look at the OPs question then.
In your opinion will re-piping half of the pipe from the meter with 28mm and joining the existing 22mm make any difference? If so - how many mbar difference?
0.29mbar difference.
But then you knew that from the Venturi effect ,didn't you Jo.
But then you knew that from the Venturi effect ,didn't you Jo.
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So is Sooey's advice good advice? .29 is pretty much here nor there is it?
If I'd suggested that to the OP I'd have been ridiculed - so come on guys - tell Sooey what you think of his advice.
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If its 15m (13 + elbows) and boiler is 4m3/hr then his pipework will have somewhere in the region of a 3mbar drop (15/5...actual length/max length)
Change half say 7.5m to 28mm would give the first section 7.5/40= 0.18 add that to 7.5m of 22mm pipe for the second section 7.5/5=1.5
Total drop 1.68 so still not good enough!
So in answer it will make a difference but still not be within the rules.
Now I've used Ige/up/2 others will use other chars and get different values.
Depends on which book as up2's lengths are in increments of 5m, other books use increments of 3m but I ain't got them to hand.
Change half say 7.5m to 28mm would give the first section 7.5/40= 0.18 add that to 7.5m of 22mm pipe for the second section 7.5/5=1.5
Total drop 1.68 so still not good enough!
So in answer it will make a difference but still not be within the rules.
Now I've used Ige/up/2 others will use other chars and get different values.
Depends on which book as up2's lengths are in increments of 5m, other books use increments of 3m but I ain't got them to hand.
Nobody said otherwise.
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