50mm pipe for waste plumbing

Horlock

I'm feeling really confused after reading that I need 50mm waste pipe. The reason for the need is the length of the run before it reaches the 110mm soil. But that isn't really my confusion.

My confusion stems from the fact that I've bought a 50mm trap and 50mm pipe.

The trap is this one http://mcalpineplumbing.com/traps/bath-traps-fillers-and-wasteflow/sm10v-50mm-seal-anti-syphon-bath-trap-cleaning-eye

The tube is this one http://www.toolstation.com/shop/Plumbing/d20/Plastic+Solvent+Weld/sd2885/Solvent+Weld+Waste+Pipe+30m/p85290

The problem is that the diameter of these two are not remotely similar.

The outer diameter of the tube is 60mm where the trap appears to need an outer diameter of about 45mm since the tube fits inside.

So I'm confused and I don't know which I'm supposed to be looking at. They certainly don't appear to be remotely compatible with each other, but I'm not even sure which diameter the regulations appear to be suggesting I should be using since both are clearly called 50mm.

Any advice gratefully received.

I_have_spoken

50mm seal spec. for a trap refers to the depth of water retained in the trap to seal against gases from the drains.

The trap you've bought has 1.5" BSP fittings.

flashg67

Edit - Beaten to it by an expert - I was nearly right!?
Is it that the trap has ' 1½" Multifit Compression Outlet' rather than a 50mm outlet, with the 50mm mentioned on the trap referring to the knurled fitting? (Only my guess from looking at the tech drawing on the Mcalpine page)

I always get totally confused & annoyed about the unnecessary mixing of imperial. metric & BSP measurements. I have a bag of unused fitting as testament to this.

I find Screwfix quite good at sorting stuff if you have a store nearby

Horlock

Thanks folks. So next question is can I get what I want? Can I get a trap which feeds into a 50mm pipe - or am I supposed to have a standard trap and then up the pipe radius to 50mm?

MX5huggy

The latter, run 40mm till you join the main run or 2 or more connections come together.

Furts

If the waste pipe is from a bath is ought to be 50mm diameter. If from a basin or sink then 40mm would be OK.

Horlock

Furts wrote: »

If the waste pipe is from a bath is ought to be 50mm diameter. If from a basin or sink then 40mm would be OK.

Waste is from a bath, but it just confuses me that I can't get a trap which goes to 50mm pipe.

It doesn't need to join the basin at all, but I read it should be 50mm if the (almost) horizontal run was more than 3m.

I'm guessing building control aren't going to check it - from what I hear they only check the electrics and I can't see how one extra metre forces me to need a larger diametre pipe - it still has the same quantity of water flowing along it at the same rate.

Mr.Generous

Furts wrote: »

If the waste pipe is from a bath is ought to be 50mm diameter. If from a basin or sink then 40mm would be OK.

I think your confusing sizes, 32mm (1 1/4") is normally for hand basins and 40 mm (1 1/2") for baths and kitchen sinks.

50mm waste is used for long pipe runs or commercial applications.

MisterP123

Can we chuck in the difference between pipe and tube as well.... Seeing as they were both mentioned :rotfl:

Horlock

Mr.Generous wrote: »

I think your confusing sizes, 32mm (1 1/4") is normally for hand basins and 40 mm (1 1/2") for baths and kitchen sinks.

50mm waste is used for long pipe runs or commercial applications.

I don't think I'm confusing sizes. As I say this is for more than 3 metre run, ie a long pipe run, hence need for 50 mm.

I know that 40 mm is normal for short runs, but I have a long run so need 50mm, my issue seems to be that I can't get a connection from the bath which will give me 50mm. It would seem strange to start at 40mm then up the pipe to 50mm at some random point between the bath and the 110mm? I don't see how that would help with the longer pipe run.

Ruski

40mm is the right size for the bath waste - continue with that until your next outlet is connected to the run (basin etc), then up the size to 50mm and continue to the stack.

In 'most' bathrooms this is overkill, but if you have an inspector showing special interest in your white waste, then humour him/her.

one tip - if possible run separate wastes from bath, shower and sink etc, as this will eliminate siphonage/gurgling.

HTH

Russ