gas pipe sizing

[Dotty]

I've also merged both your threads to avoid confusion.

 

[Inverness]

thank you. shaun has put me into the right direction so hopefully reading this is the proper way of understanding it.
when you do gas pipe sizing does everyone do this table to work out the size of pipe?

 

[ShaunCorbs]

thank you. shaun has put me into the right direction so hopefully reading this is the proper way of understanding it.
when you do gas pipe sizing does everyone do this table to work out the size of pipe?

ive got a mears calcs but if i have to back to the books

 

[ShaunCorbs]

A - B 5.7m3 2m : 2m , 1.5m = 3.5m, 35mm

B - C 1.0m3 1m : 1m , 0.0m = 1.0m, 15mm

B - D 4.7m3 4m : 4m , 0.5m = 4.5m, 35mm

D - E 4.7m3 2m : 2m , 0.5m = 2.5m, 35mm (will be ok in 28mm)

E - F 1.0m3 1m : 1m , 0.0m = 1.0m, 15mm

E - G 3.7m3 2m : 2m , 0.5m = 2.5m, 28mm

G - H 1.0m3 2m : 2m , 0.0m = 2.0m, 15mm

G - J 3.2m3 5m : 5m , 0.0m = 5.0m, 28mm

not 1000% as all ive got at home is a ft3h mears calc 😀

 

[Inverness]

 

[ShaunCorbs]

looks fine mate starting to get the hang of it ?

 

[Inverness]

its down too you mate.ill do more and let you see.

would it be good practice to have the actual pressure loss at 0.5 instead of being close at 1.0.?

 

[ShaunCorbs]

its down too you mate.ill do more and let you see.

would it be good practice to have the actual pressure loss at 0.5 instead of being close at 1.0.?

in theory yes but then you start going big for example 22mm for a gas fire (7kw) etc

but depending on site conditions running 28mm to as close as you could to the boiler wouldn't hurt

most manufacturers allow 1.5mb at the gas valve test point anyway, and you will find you will have a little wiggle room as the figures arnt that accurate etc (people state different for pressure loss on elbows etc) and im sure you could get it lower by doing some formed bends

 

[Inverness]

Hi Shaun how do you get the progressive drop on the last appliance?

 

[ShaunCorbs]

Hi Shaun how do you get the progressive drop on the last appliance?

add (col 9)

1-2, 2-4 and 4-6 if you mean cooker

1-2 and 2-3 if you mean gas fire

1-2, 2-4 and 4-5 if you mean boiler

 

[Inverness]

 

[Inverness]

here is some more gas sizing practise attempts.
I've think I've manage to grasp it now.

the main pipe run c-d to find out its progressive pressure drop you add the actual pressure drop from previous b-c progressive drop ?

 

[ShaunCorbs]

for the progressive pressure drop of lets say F



A-B + B-D + D-F = progressive pressure drop of F etc

 

[Inverness]

for each appliance to find out its progressive pressure loss you need to add all sections of pipe that feeds that appliance so by finding out f you have to plus all the actual pressure drop together ab- bd- df.

but what about pipe work that isn't feeding any appliances??

 

[ShaunCorbs]

for each appliance to find out its progressive pressure loss you need to add all sections of pipe that feeds that appliance so by finding out f you have to plus all the actual pressure drop together ab- bd- df.

but what about pipe work that isn't feeding any appliances??

yes and what do you mean like A-B and B-D ? just add upto that point

like you want to know the ppl of D

its A-B + B-D = ppl of D

 

[AlexGas]

View attachment 26896

Try to do your calculations using latest BS figures for pressure loss of fittings. See if you get the same result.

 

[Inverness]

Isn't the copper institutions bs figures?

 

[AlexGas]

Isn't the copper institutions bs figures?

Can you see the figures in my previous post?

 

[Inverness]

I have the bpec Gas saftey manual so I'll start and do more practice attempts with these pressure loss figures it even goes up to 35 mm.
Thanks again.
It takes time to understand it and the books are written in such away that it's designed to be taught by a teacher. But who needs a teacher when there is you guys.lol
I know it's early but I don't begin my gas until March next year so I'm studying for it now so when the teacher starts explaining things I'll no what he is talking about and I'll be able to explain it in a easier format to my friends in the class too.
My boss is gas safe but we don't to a lot just commissions boilers and sometimes re-rout gas pipe to suit new boilers. But with the plumbing forum I'm teaching my boss new things too.

 

[AlexGas]

All the best, hope it goes well for you.