Plumbing sizes, i'm confused

[NorthernSky]

i need a 25mm fibre washer for my shower. 25mm is the outside diameter
everything to do with plumbing seems to be in Inches.
now to me 25mm is equal to 1"

why is this chart telling me 1" is 30mm? (seller on ebay)

is plumbing measured by the INSIDE diameter?
in that case i'm going to need the 3/4" washer, bit confuddled
also what is CTC

 

[fossyant]

Its 25mm, not 30.

 

[Ian H]

Imperial pipe was measured internally. Metric pipe is measured externally.

 

[sleuthey]

 

[battered]

As others have said, imperial pipe measurements are internal diameter of the pipe. You should try working in dairies, a 1" pipe fitting needs a spanner with an opening about 2" across .

 

[neil_merseyside]

As above about imperial measurements being internal diameter of pipes. For a shower union a bath tap fibre washer is usually needed (nom. 3/4") and that will measure a gnat's nudge under 25mm when new and dry, so will be around 25mm when splayed, and wet.

 

[NorthernSky]

hey folks, follow up to this. now i know the size i need can someone tell me what washer type i need.
i bought these from screwfix ( https://www.screwfix.com/p/arctic-products-flexible-tap-connector-washers-10-pack/5547j ) but they have a hard surface. when installed it just leaks.
it's like the intact washer is a softer type that has expanded and filled the gap?
i have this mixer unit. it's the washer that sits at the cold inlet on the wall
https://www.idealstandard.co.uk/products/catalog/showering/mixer-packs/a4741

 

[neil_merseyside]

Fibre washers are meant to swell and seal, but only the bit nearest the water actually swells the rest stays pretty much dry under compression from the joint, the joint isn't twisted/distorted is it?

 

[NorthernSky]

Fibre washers are meant to swell and seal, but only the bit nearest the water actually swells the rest stays pretty much dry under compression from the joint, the joint isn't twisted/distorted is it?

thanks, yes i thought that what's meant to happen with them
the joint looks fine, i think it could more be the surface of those fibre washers i bought, they have like a shiny/hard surface before it gets to the fibre
was thinking i could sand that away and try it. failing that i may look some of the red fibre washers (similar to the one that's intact)
i take it fibre washers are widely common with plumbing?
what about rubber washers, where would they be used more

 

[neil_merseyside]

Washing machine washers are 3/4" and rubber.

 

[keithmac]

Washing machine fittings contain the washer. A rubber washer will spread out sideways when squashed so not suitable for all applications.

Same as O rings.

Have you got a picture of the fitting?.

 

[NorthernSky]

yes will grab a pic when i can
ironically it's not leaking as bad just at the moment, since i've had it off and put it back on last time
will be worth having a spare though

 

[Pale Rider]

yes will grab a pic when i can
ironically it's not leaking as bad just at the moment, since i've had it off and put it back on last time
will be worth having a spare though

A couple of bodges/temporary/permanent fixes.

You could wrap a length of cotton fibre string around the fixing, or even cut a short length from a traditional dishcloth if you have none to hand.

Or you could create your own 'fibre' washer from a cereal packet.

Best to use a bit which isn't printed on either side, or use two pieces sandwiched, with the unprinted sides facing outwards.

Best of all, obtain the correct part, but this is the internet, the home of making things needlessly complicated.

 

[Profpointy]

Well worth buying a sorter box of mixed plumbing washers and spares for a fiver or so.

Anyhow my guess would be it's a washer for 3/4" BSP.

 

[NorthernSky]

finally got a picture of this.
intact washer from the hot side. it is quite thick but i think this is because it's expanded over time? doesn't seem to be made of rubber
if a rubber replacement worked i'd try that though


removed the mushed one


still struggling to get a replacement