Where to get very large food grade O rings?

[hotponyshoes]

Thanks.

I can line tins well enough but the O ring makes it easier. It'd need to be food grade and is it possible to glue silicon? I thought one of its properties was that not much stuck to it.

RTV106 is what I use to bond silicone. That's withstanding the weight of a horse though so any old rtv might work?
Just give it a few days (ideally a week) to cure fully.

Not that that's relevant as the big ones I have are PTFE.
But they are only about 215mm x 4mm section so a bit small anyway!

Another option might be the seals from the lid of a clip-top food container although you would have to do the maths to work out what size rectangles make up a 250mm circle!

 

[Mr Fro]

Never dealt direct but used to do some work for Hovis who had Eriks onsite. Are they reasonable or extortionate?

Same sort of area as Trelleborg really.

 

[Screwdriver]

Might it be possible to use metal. Something like annealed copper tube (brake line).

 

[Screwdriver]

I've got some lovely asbestos packing here.

not food safe tho is it.

 

[Screwdriver]

Neither is old brake tubing haha!

why would you want to use old brake tubing?

 

[Ross365]

PTFE is not a good O ring material. It is not an elastomer, so tends to suffer permanent deformation rather than conform and then bounce back. For food-safe at 200'C, I suspect that silicone and EPDM may be the prime candidates. Kalrez might work, but weight for weight it is more expensive than gold .

 

[hotponyshoes]

These ptfe ones are quite springy, I don't know if you get different types of it? Or if they are mixed with something else?
The parts list just describes them as "ptfe seal"
They are good for 250degC

But you are right about them deforming, they get replaced every 6 months but that's being used a few times a day 5 days a week.

 

[Ross365]

Silicone o rings will only do 150-180° As far as I know. Viton May be better?

Viton is a good rubber, but it's this food-compatible need that I've never had to deal with previously, and I don't know if Viton is good for that

 

[Hitch]

A VMQ o-ring would be ideal, think they're heat resistant to about 230°C and food safe.

Alright saying a silicone o-ring, but there are different types. VMQ, PMQ, and some others I can't remember.
Slightly different chemical makeups, depending on application.

You could try M-Seals in gateshead.

There recently made some bespoke o-rings for a project I've been working on.. caustic resistant, flexible, metal detectable, food safe... and chuffin expensive.

 

[Ross365]

These ptfe ones are quite springy, I don't know if you get different types of it? Or if they are mixed with something else?

You could take a used one and cut it in half and see if it is hollow? I've used metal O rings for really high temperatures that were made that way; to a limited degree, they too compress in a returnable way (damn clever!). I've also seen rubber O rings with a transparent layer of silicone on the outside; cannot recall where they came in.