Gas bayonet - BSP type?

[Tim Watts]

I expect some shouting down for asking a gas question in public, I'll do it anyway:

What is the correct female part to mate with a standard cooker bayonet above - 1/2" BSP parallel or taper?

I notice that Rocol Threadseal XS (which I use here and there on water and love it) is rated for gas (natural and LPG - mine is natural). Any reason not to go for it in preference to gas PTFE?

Those are the only questions - I've been through the checklist:

Line hole through cavity wall with gas proof tube; Slight downwards angle towards outside where 95% of the run will be; Seal said tube to wall both sides (I have flame grade mastic) Seal copper gas pipe to tube on inside only. Pressure test - have manometer and done this before when I capped the old supply line off. Pipe size calcs - done and not a problem,

I don't think I missed anything.

Cheers

Tim

[Andy Dingley]

Whilst that's true for a compression fitting (metal-metal or taped) it's no longer so true wiith liquid pipe thread sealers.

How acceptable is it to use them in this way, in terms of gas and quality of workmanship? They certainly seem to have replaced the old "packing with washers" tricks for water plumbing where you need a thread to stop with a particular orientation.

[John Rumm]

Ideally taper, but if the male part is tapered, then you can make a sounds joint into a parallel socket usually.

(I have also seen in the past bayonet sockets that have a right angle

15mm compression fitting on them - that makes for a quite simple installation, but you need to remember to support the pipe well close to the fitting).

You can use one or the other as the preference takes you - just not both.

"Let by" test - just in case the main gas c*ck leaks a bit...

[Tim Watts]

I'll go with the Rocol on then on the wall and PTFE on the hose (it's hotter there plus don't really want to scunge up the cooker union in case of needing to change the hose).

Of course - thanks John. I did do one of those last time, but forgot to mention it.

and of course, I suppose it is worth mentioning that doing a pressure drop test with the new cooker connected but burners turned off is a good idea, to prove all the valves an flexi pipe are good...

Now to choose a cooker. The gas is a very simple run - about 2m of external copper then dive in through a hole more or less direct to site.

Cheers

Tim

[Andy Wade]

Surely the usual fitting to screw the bayonet coupler into is

is 15 mm solder capillary 'input'?

[John Rumm]

Yup, there are a bunch of variations of that theme. Some capillary some compression, and quite often with a side rather than end entry.

(if using one like in the picture, remember to screw the socket in before you fix it to the wall - otherwise you can't turn it)