G4 purging help????

[cudney1]

Hi there,


i am really struggling to work out the proper procedure for working out the purge volume for a G4 gas meter. The badge capacity is 6 m3/h, viper book doesn't mention G3 meter but it says to multiply the badge capcity by 5 and use this, but that would be 30m3/h but where do i go from there . But then i've read on a metric meter to just purge 0.01m3. i'm so confused as to what is the right way if someone could help and maybe show me a formula or way of writing it out i would be so greatful.

im currently try to get my gas portfolio up together but if i cant even work out the correct way of purging a G4 meter i have no chance

thank you so much and sorry if i sound thick ive just read so many contradicting answers today

 

[Simon F]

the 6m3/H is the amount of gas that the meter can pass in 1 hour. an imperial meter would be 212ft/H the badge capacity is (0.071ft/rev) the volume per revolution of the bellows within the meter - 4 in total. the purge volume is 0.071 x5 = 0.355ft/3
4 for the meter and 1 for pipe work. this is a third of the dial revolution ( full rev being 1ft3 of gas)
but on the metric meter just as you say purge to 0.01m3

 

[cudney1]

Thats great thanks for the help

 

[cudney1]

i have a picture here of a G4 meter. i am basically doing a write up on the purging and it is hard to work out which one was the badge capcity. there is something saying 1 IMP = 0.01m3 does this mean that this is the volume that must be purged. i work with someone who isnt really very helpful when it comes to teaching. i want to make sure that i give a good reason and the proof for saying the purge volume should 0.01m3 rather than just saying it. if that makes sense

thanks again

 

[johnnyplumb]

the purge vol for the g4 meter with 28mm pipe is 0.01. if you take the reading on your meter picture as an example, the reading is .448 so purge to .458

 

[kirkgas]

purging volumes can be different depending on pipework size as well, confirm from table in either your training notes or IGE/UP/1B (tightness testing document)

 

[ADM360]

While your on the subject!! if you can't leave an open end unattneded! what is your chosen method for purging?

 

[CMairiD]

i want to make sure that i give a good reason and the proof for saying the purge volume should 0.01m3 rather than just saying it.

In your picture, 2.0 dm[SUP]3[/SUP] is the volume. 2.0 dm[SUP]3[/SUP] = .002 m[SUP]3[/SUP] * 5 = .01 m[SUP]3[/SUP]. That's your five times badge capacity on metric meters

 

[kirkgas]

While your on the subject!! if you can't leave an open end unattneded! what is your chosen method for purging?

you have to stand by the purge point while open, so the only way to do it (properly) is to take a note of the meter reading, go to a suitable purge point and purge for a "reasonable but not excessive time" this needs to be learned, and is approx 20 odd seconds using 4 burners on a hob, you then need to close your purge point and go to the meter to check the right volume has passed, if not make an assessment of how long you still need to purge (after 20 seconds you have purged 50% then you need to purge for another 20 seconds etc, just work it out as best you can) return and open purge point, assess time required, close purge point then return to meter and confirm full volume has passed, if not do it again etc etc,
or do you mean how it is done in the real world, which is "right missus, you will prob smell some gas in the kitchen, keep oot, im going outside to the meter, i need to make a phone call anyway, then you open the 4 burners at the hob and nip outside turn the gas on at the meter phone your mate about the 5 a sides tonight and by the time the call is finished the correct purge volume will prob be passed, DO NOT phone your wife to ask her about a Christmas/Birthday present, this is highly dangerous for your wallet and for the customer as by the time this call is finished her whole hoose will be full of gas

 

[Simon F]

In your picture, 2.0 dm[SUP]3[/SUP] is the volume. 2.0 dm[SUP]3[/SUP] = .002 m[SUP]3[/SUP] * 5 = .01 m[SUP]3[/SUP]. That's your five times badge capacity on metric meters

thanks for that post, made the clearer for me

 

[cudney1]

In your picture, 2.0 dm[SUP]3[/SUP] is the volume. 2.0 dm[SUP]3[/SUP] = .002 m[SUP]3[/SUP] * 5 = .01 m[SUP]3[/SUP]. That's your five times badge capacity on metric meters

that is perfect thank you for the help, it makes it so much clearer when someone tells you what your looking for

 

[GasmanxxxR1]

In the real world to relight appliances eg a hob i just stand at the hob, light it, when it goes out because of the air just keep trying to relight it. When its back alight stand there and observe flame picture then move on to next appliance