In article
,
4square writes

I should add, the chap I spoke to at Pegler this morning did say
there wasn't a lot of difference between red and green, but didn't
say how much! In the shed just now, I applied the trusty Aldi
digital caliper to a new red o-ring I have, and although tricky to
measure soft materials accurately, it seems to be 1/16 inch by half-
inch OD. The material is softer than some ordinary o-rings I got at B
& Q, but some of them are the right size - they are in packets
according to material dia., not OD. I might try to contact a trade
seals supplier, and find out about different materials. My house is
1964, original rads. and valves. I don't like replacing things
unless essential!

I've found http://rswww.com a useful one-stop shop for this sort of
stuff and their data is good, nitrile 1/2" o/d by 1/16" material is size
BS012, RS code 689-631, 2.11+vat for 50. At those prices you can afford
to buy a range of sizes. RS will deal with individuals via the website
no problem but can get a bit arsey at the trade counters.

Alternatively, use their data to select, then buy from a local
engineering supplier using the BS size/code.
--
fred
Plusnet - I hope you like vanilla