I think I read somewhere that applying a small amount of silicone grease to the rubber diaphragm washer in a toilet cistern water inlet valve will improve the seal and increase the lifetime of the washer.

Is this true?

I always use silicon grease on all threads and seals when doing plumbing work. Not sure if it makes them last longer, but threads are easier to snug up, and seals seem to seal better. Also, and this is the major issue, getting things apart in the future is much easier. For non-plumbing jobs, stuff like anti-seize is also useful on threads you want to get apart later -- lug nuts, stuff exposed to the weather, etc.

73 /paul W3FIS

On 12/27/2012 7:47 PM, wrote:
I always use silicon grease on all threads and seals when doing
plumbing work. Not sure if it makes them last longer, but threads are
easier to snug up, and seals seem to seal better. Also, and this is
the major issue, getting things apart in the future is much easier.
For non-plumbing jobs, stuff like anti-seize is also useful on
threads you want to get apart later -- lug nuts, stuff exposed to the
weather, etc.

73 /paul W3FIS


I've used "silicone" grease for outdoor antenna connections because
silicon is too abrasive but makes great semiconductors. The best thing
to use on plumbing connections is Teflon bearing pipe dope or a product
I use for a lot of things called Leak Lock. ^_^

TDD

On Thu, 27 Dec 2012 16:59:22 +0000, M.Joshi
wrote:


I think I read somewhere that applying a small amount of silicone grease
to the rubber diaphragm washer in a toilet cistern water inlet valve
will improve the seal and increase the lifetime of the washer.

Is this true?

Generally, yes.

FluidMaster doesn't grease the rubber diaphragms in their flush valves when they assemble them at the factory. Also, on their carded replacement rubber diaphragms, the installation instructions don't say anything about applying grease to the diaphragm. If there were any benefit to be had in using grease on the diaphragm, they'd grease their diaphragms at the factory before installing them in new valves, and they'd supply a tiny bit of silicone grease with their replacement rubber diaphragms.

I believe the fact that they don't use grease or recommend using grease means that they can't see any benefit in greasing the diaphragm before installing it either.