Gas Pipe Sizing Calculations

[princegoose]

I need to add a cooker supply and have been trying to work out the sizing of the pipe but have come unstuck as can't see anything over 30 meters in 'THE' chart. Have checked Corgi, Viper and old text books with no luck.

All lengths include allowance for pipe and fittings (copper).

A-B = 7.5 Meters
B-C = 5 Meters
B-D = 28.5 Meters

B = TEE
C = BOILER @ 2.6 m3/h
D = COOKER @ 1.04 m3/h

Using the chart, so far, A-B needs to be 28mm, B-C needs to be 22mm but as the theoretical pressure loss over the B-D is 0.33mbar I haven't a clue what to do as multiplying it by 3 gives 85.5 Meters which there isn't an option for.

What can I reference?

Does anyone know? Other than saying ''just use 28mm for a few extra meters son''.

Thanks

 

[AlexGas]

The CORGI book is one way to work out the pipe sizing. Try Progressive Pressure Drop calculation here:
http://www.ukcopperboard.co.uk/lite...ion-Tips/Domestic-gas-planning-and-sizing.pdf

 

[princegoose]

Hi, thanks.

Where in the corgi book does it show you how to calculate the size, other than having to use the table/chart?

 

[AlexGas]

Page 107

 

[princegoose]

Thanks Alex.

I've already tried that. The problem I'm having is that the table doesn't go above 30 Meter lengths. As the last length of pipe I have is 28.5 Meters long when I multiply it by 3 (to get the pressure loss (0.33mbar) relevant to the length) it becomes 85.5 Meters long. I'm sure there's a formula to work this out. Or is there another chart out there which goes longer than 30 meters?

 

[AlexGas]

It is very tight! If you ran your 28mm for extra 13m pass the T (the rest in 22) - the cooker run Pressure Drop will be 1.19 mbar. Not ideal. You might get away with it though, there's plenty of discharge on your last 22mm length. I'd give the Gas Safe a call.

 

[AlexGas]

Get your head around the Progressive Pressure Drop calculation at http://www.ukcopperboard.co.uk/liter...and-sizing.pdf

See Table 2. Your drops will be different.

 

[princegoose]

Ahhhh, I gotcha, thanks, I'll have a good look at it this evening.

Thanks mate.

 

[AlexGas]

Here it is:
A-B 3.64m3/h Total Length 7.5m Chart Length 30 in 28mm
To get the Pressure Loss – divide your Total Length by Chart Length.
7.5m/30m=0.25mbar A-B Pressure Loss is 0.25mbar, You see what I’m saying – it’s not 0.33mbar! You've got more money to play with.
Now you have to do the rest…
As I say - ran 28mm for another 13m and see what you get. It's just above 1mba (NCS). Talk to GS.

Hope it helps.

 

[Simon F]

I had heard of 50m pipe sizing charts but never seen one until recently when I bought the John Reginald combi book, it has a 50m chart.