Does anyone else have this problem?
I'm running an Oneida 3hp SDG with 8" mains and 6" drops. Most of my blast gates are 6" self cleaning gates. I've noticed that quiet often when I shut down the system all of my closed gates vibrate and create a lot of noise for a few seconds. There's no large vibrations coming from the collector. You can't even feel and vibrations in the pipe near one of the offending gates. I think the issue is with some sort of resonance in the pipes due to the pressure changes.
I've tried damping the gates with magnets, but that only helped a tiny bit...could use more weight. Any ideas?