UKH

I’ve just bought a new 3-way fridge (12v/240v/ gas) to replace the ancient one in our camper van; the new (Dometic fridge) has an 8mm tube to connect to, but the tubing installed in the van is smaller. I thought it was 6mm so bought an 8mm to 6mm reducer ( compression) but can’t get the olive onto the 6mm tube as it’s too tight. I am wondering if if could be 1/4” rather than 6mm tube as the van conversion was done 20+ years ago - was 1/4” tubing (external diameter) even a thing then? I can’t seem to find any 8mm to 1/4” couplings out there. Does anyone have any wisdom/ ideas how to solve this? Measuring the tubing with a vernier caliper it is 6.3mm external dia.

Have you tried using a quarter inch olive?

On the bigger compression fittings 3/4" olives work in 22mm fittings with 3/4" pipe .

https://www.camperlands.co.uk/copper-pipe-coupling-8mm-to-1-4-female-bsp.ht...

Have you tried using Google.

Thanks for the suggestions - I’ll get hold of a 1/4” olive to try first as that sounds possible. 

I had tried extensive Googling- I’m not familiar with BSP fittings though and was looking for something with compression fittings both ends.....happy to be told there is a way using that type of fitting....

Not sure exactly how it works, the plumbing industry appears to do its level best to frustrate DIY ers , but a 1/4" olive may fit a pipe of 1/4inch internal diameter.

Perhaps best to go to a plumbers merchant or get the actual measurements of the olive required.

A lot of hassle for a piece costing a few pence

reply to Mick Bradshaw: If you can find a 8mm to 1/4” compression fitting that should do the job. Even better if they come with copper olives as they seal better than brass olives on copper pipe. When you have got the connection made you must either get it checked by a qualified gas engineer just to make sure there is no leaks. BTW I am a qualified lpg engineer. If you need any advise get in touch.

Hi Rick, you have got it a bit wrong, a 1/4”olive fits over a 1/4”pipe.

I apologies for stating the obvious (and not being of any help in the process) but have you got some means of leak testing the job once you have found a suitable fitting?

And have you read up on correct use of gas fittings? Ideally a copper olive or Truma fitting with no sealant on the olive or threads (it should for it's own seal) and don't over tighten it, nip it up appropriately then leak test once pressurised and nip it further if you see bubbles forming once you've applied the leak detector spray / washing up liquid.

I don't want to come across as condesendign and I'm no expert but always play is safe when playing with gas appliances. A family friend was fitting a 3 way fring to his camper and it ended in a burnt out shell of a van on my md drive and a lot of missing hair. 

Thanks for the advice - if I could find an 8mm to 1/4” compression fitting that would make life very easy - but these don’t seem to be available as far as I can see.

You don’t live in the south by any chance?

youtube.com/watch?v=M9x_D_VxT_Q&

this gizmo is on u tube,the Propex Expander. Genius invention.I was thinking of how to do this with 3 screwdrivers levering in a circle around a block of wood.Then I thought..mebbe summat on u tube!

A local caravan/camping place rather than plumbers merchants might be worth a shout.

We had to do something similar a few years ago and I think we ended up getting an end-feed solder fitting. It wasn't the 'right' size, but a minimal level of skill with soldering and a bit of time/patience should see you right (obvs get it tested).

Hi Mick, sorry but I live in Yorkshire. I have been looking in my boxes of fittings, but I could only find an 8mm connector. BTW 8mm is very close to 5/16”.

If you can find a plumbers merchant that stocks “Wade” fittings the do 1/4” - 5/16” straight connectors. If you find a supplier tell them that you want copper olives. Hope this helps and it will keep you safe.

regards John 

Buy a 1/4" copper to 1/4" BSPT male fitting, an 8mm copper to 1/4" BSPT male fitting and a female/female 1/4" BSPT connector and screw it all together. That´s the "traditional" way to do it!  ebay is your friend

That is one way to do it but there are too many joints to leak, its also not very good practice with regards to safety.

That sounds plausible but probably too easy ,  but is  1/4  inch the internal or external diameter ?

Well perhaps but I was assuming if the OP was competent getting the compression fittings tight then a couple of NPT fittings would present no challenge!

Incidentally here in Germany (I´ve installed and repaired gas systems in yachts and the rules are the same as for caravans/vans) normal compression fittings are prohibited for copper, you must use reinforcing sleeves inside the tubing and declare them when the system is approved and at the two yearly tests. With the invitable vibration the copper hardens and the fittings are no longer tight. On boats we always ripped any compression fittings out and hard-soldered them anyway, in a van a gas leak is a "bit" dangerous, in a boat it´s really dangerous!

Hi Jimtitt, that is very interesting with regards to regs in Germany. I worked for a British camping company for 6 years around Europe but mainly France with the odd trip to Germany and Switzerland. On most of the British made mobile they used Wade compression fitting onto 15mm copper pipe with very little problems. The french mobiles had all joints on the gas system hard soldered. With regards to leaks on vans, they should have drop holes under all gas appliance in case of any gas leaks. I am with you fully with regards to boats.

regards John

All pipes are measured on the O.D. Not the I.D.

regards John

At least with a rough old van the doors seals leak enough and when you open the door the gas falls out anyway, with a boat you end up with a complete disaster! I earned my years keep in Spain over the winter 87/88 rebuilding a yacht that had been completely wrecked by a gas explosion, just the hull, engine and rig was salvaged.

My first bigger yacht had gas lamps installed and every compression tee leaked, with soft tube it´s invitable really which is why the standard for us calls for reinforcing sleeves but even then I´m not inspired, hard solder every time or threaded fittings.

A couple of times we had customers who bought used British yachts (back when such things were desirable) and as gas certificates are a requirement in most marinas (and campsites) we inevitably ended up ripping the old system out completely and replacing it properly. The best single item one can ever install is a Trumatic shut-off valve and learn to use it EVERY time.

If the OP system is 1/4" it must be dog old anyway so I´d just replace the piping throughout!

Is that just with modern metric pipes?

In the older houses I have altered the plumbing on in Cumbria, the so called half inch copper pipes, 0.5 inch =12.7mm, the 15mm olives work on both, so I assumed because the external diameters are so similar.

On so called 3/4 inch , 25.4*0.75=19.05, the 22mm olives are just a bit rattley on 3/4" but not 2.95mm slack.

Using the correct olive seems to get the job done.

Once helped plumb in  a sink in france.

Their fittings seemed even more confusing

You mentioned copper hardening due to motion earlier, would you re-pipe a small vessel in something like stainless or stick with copper?

I used to work on ships, and all the pneumatics were done in copper.
Mind you, the ships were in for total refits every 3 or 4 years, completely trashed!

Thanks Jim/ John

I appreciate that all soldered would be a better solution, but the tubing in to the fridge doesn’t appear to be copper ( as it’s silver) so there will have to be a compression fitting involved somewhere.

I’ve ordered some 1/4 “ olives so first choice will be to see if using the 6mm to 8mm compression fitting I have will do the job with the existing pipework

If not then I’ll hunt around to see if I can find either a 1/4” to 8mm soldered fitting or the 1/4” to 8mm that I had in mind originally ( although that looks a long shot)

Failing both of those then replacing all the pipework with 8mm it will have to be.

Incidentally, having a flexible hose connection to the fridge would make life much easier ( as the fridge fits in a fixed cupboard  unit) but the Dometic instructions specifically advise against that. There is already flexible hose from the regulator to the fixed pipework ( can’t see any way around that) and again from pipework to cooker. Is it strictly not done to use similar in fridge installation, or Dometic covering themselves?.

Advice much appreciated - and I’ll post something climbing related next time!!

Copper every time, they don´t really make stainless soft enough to be able to fumble it through. Don´t even know if there are small enough compatible fittings made and I wouldn´t want to be welding them on anyway (I´ve done enough bigger ones in larger boats not to want to get involved).

I´m off now to install two steam engines, welding 130mm stainless tubing is more my kind of thing!

The standard in Germany prohibits flexible connections to the appliance (except for gimballed ones in boats) and I expect the British Standard (BS EN 1949: 2001 + A1:2013) does the same since it´s probably based on the original DIN standard. The only flexible allowed is 40cm? to the gas cylinder which must be inside the sealed stowage (with an external vent).