O ring sizes for radiator valves

[bsr]

Hello, do you know what size the o rings are, which are used to seal the bleed valve and blanking cap against a radiator or towel rail? Quite often when I take these off (eg to add inhibitor) they come off in bits.

I've found an o ring chart with a size 19 which is as follows. Does that sound right?
ID 20.3mm
OD 23.9mm
Diameter 1.8mm

Alternatively Ebay has 20mm x 2mm.

 

[ianmcd]

just use PTFE tape

 

[bsr]

Ah OK is that the standard bodge? Do I roll it into a sausage as a face seal or use it on the thread like radiator tails?

 

[ianmcd]

Its not a bodge and will last a lot longer than the cheap O rings that come with the plugs, I do both as you describe start with a few wraps on the thread then roll it a few wraps to make a face seal, never had one leaking, seen many O rings splitting on rad plugs

 

[bsr]

Done, seems to be working well. Thanks.

 

[UsuallyAtSea]

I know the thread is old but for future reference, ORings can be a good solution, especially if the plug has an ORing groove (quite common for parallel thread - eg Plumbsure radiator plugs and vents have ORing groove and not much thread for PTFE Tape). I use this joblot of ORings from RS and I've found them to fit radiator plugs perfectly with or without grooves.

RS PRO Nitrile Rubber O-Ring O-Ring, 18mm Bore, 23mm Outer Diameter | RS

uk.rs-online.com

 

[aveatry]

I have the o rings too on my stelrad radiators and they are starting to fail as well