French pipe fitting numbers? What do they mean?

I purchased a couple pipe fittings for a pump today. I eyeballed them at 1" and then at the Brico I eyeballed again and picked the 26 x 34 (they did have a 1 cast into the fitting body of one fitting). They fit just fine.
Does anyone know what the two numbers refer to? Is it the inside and outside diameter? Are the threads metric or are they something unique to France?

And a related question. I need a 1 1/4" F (eyeballed) to 1" F reducer. The 2 Brico’s here only have up to 1" fittings. Is there such a thing as a plumbing supply store for DIY in France or am I resigned to calling a plumber?

Internal/external diameter - e.g. 15/21 is 1/2" BSP and 20/27 is 3/4" BSP

1" BSP is, as you surmise 26 (well, 25.4)/34

1¼" is 33/42 - Leroy Merlin have those

It’s odd that very little about a 1/2" BSP fitting is actually 1/2 an inch.


I found the fittings I need. Thanks. I really am looking forward to a real shower.
I have another question… Are all the pipe threads straight? I looked through the selection and didn’t see anything tapered and instead of teflon tape and pipe dope it appears that thread and a very light paste (almost like flux) is used?
Is there a trick to using the thread and paste other than winding it properly?

Ah, they like their “filasse” here in France, and that gunk (graisse) that you mire it in. After so many years of living here, having switched complete radiator systems, changed taps, toilets, flushes, PVC waste pipes and the like, am still not a huge fan of anything plumbing related. It is one of my pet hates that plumbing supplies are either overpriced and low-volume packaged, or don’t match the fitting that you would just like to replace without having to refit the whole pipe section, appliance, tap, toilet or whatever. Sorry, I’m a grumpy old git when it comes to plumbing.

My impression is that there is still a strict demarkation between wholesale & retail in France - wholesalers don’t want to deal with anyone who does not have a SIRET/N and retail is, as you say, quite expensive.

Depends but while interfaces external to a fitting (threads, pipe sizes etc) are standardised those “internal” are not, though I’ve had no problem with eg tap washers or obtaining a new floatvalve without having to buy the whole toilet.

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Currently grappling with a toilet flush, and discovered that the functional part of the old broken one can not simply be replaced with a current counterpart, which would have taken 5 minutes, and should in theory be possible as it is just a twist-fit body, and that instead I have to dismantle everything, remove the cistern and put it all back together :rofl: :rofl: Size is important after all, no matter what people say !

Yeah, I had to do that when the siphon failed on the loos chez moi in the UK so I guess it’s pretty universal.

On the bright side the bit of metalwork between the cistern and toilet was rusted to **** so it’s a good opportunity to replace that.

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Totally agree, one of my customers had a siret and an account with a large Co and I couldn’t believe the price he paid for some pvc valves for his pool. Sent him back with a shopping list so I could restock!

This might prove useful:


Exactly as it should be.
I spent many years in UK dealing with builders merchants to negotiate the best price to purchase materials that were my bread and butter only to see Joe Public walk in and get a similar price as he needed to buy lots of materials for his one off extension that he was going to get his mates to build for cash. Had French rules applied when Joe came to sell his house the tax man would have taken a slice from the profit of his shoddy extended house.
Trades people in France are respected for their profession having been properly trained for the job.
I served my apprenticeship and much more yet I would often stand alongside a person at the trade counter in UK who decided that as he was a bit handy he would become a builder.
No wonder builders and tradespeople in UK get a bad name wrongly tarred by the same brush used by Mickey Mouse wannabe’s.


You put forward a good point but it doesn’t require a reference to any extension built by mates. Being in the industry with mates we all help each other out when required and quite a few siblings as well.

I remember a repair job I was doing on a property and required a few bricks, the merchant tried to seriously over charge me because I wasnt buying many. I asked on that basis how much a single brick would cost? After explaining where he could put them I naturally went to a different provider.

Can’t agree I’m afraid.

I don’t know about plumbers’ merchants as my experience with them is not at all recent but I do have an account with the local builders’ merchant. It’s a long story as to why but I didn’t need a SIRET number. They stock things I can’t find elsewhere and I am certainly not in the business of building extensions or anything else :smiley: As to whether they are cheaper or not, I couldn’t say because I haven’t checked…

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And where coukd he put them? :slight_smile:

Where the sun doesn’t shine😂

Scotland ? :rofl::rofl::rofl:

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