I have a sprinkler system in the house which has an accumulator (like a
huge expansion tank) which ensures the sprinklers keep sprinkling long
enough in case of fire as although mains static pressure is good, the
mains flow rate is not high. As a result I also have a single check
valve on the cold water inlet to the house.

That valve is noisy. It rattles away a few times a second when water is
coming in and the noise travels throughout the house. How do I stop it?
Are check valves noisy by design? Do I have a faulty check valve? Is
a combination of the spring rate in the check valve and the bladder in
the accumulator resonating?

Anyone solved similar before?

Regards
Bruce