K
kirkgas
But what if you cant see the pipe work and you dont know how many fittings or how much 22mm pipe runs though the ceiling? Are you only doing purge volume caculations to check if you are allowed to purge it with out igniting. I am confused. Alot of the time you can see the pipework and you cant go ripping floor boards up.
you never need to know how many fittings are on an install to work out purge volume, its down to meter and/or pipe size, if you cant see all the pipework you need to work on a best endeavour, say 28mm pipe disappears under the floor and 8m away 22mm pipe appears up as you dont know where it drops down simply take it as 28mm all the way, the reality is it wont make much difference, remember we are nearly talking about IV and PV in the same thread, max IV for domestic ticket is 0.035m3 (approx 90m x 22mm pipe with an E6 meter, so you will never go over in a domestic as you wont get any gas out of the pipe if the appliance is 90m away from the meter, if there is any 35mm pipe or a U16 meter you need to work out IV before you start, (o.035m3 max for domestic) if you can work on it you need to work out PV so you need PV of the meter and then calculate pipe lengths (again if you cant see all the pipe or where it reduces assume larger size) once you add up all the pipe volumes, add 10% for fittings (thats why you dont need to know how many there are) then multiply answer by 1.5 lastly add PV of meter, if under 0.02m3 purge to vented area, if over 0.02m3 you need to light it as soon as you start purging