Review on ⚙️ Mueller Backflow Preventer-Vacuum Breaker FBA_108-904RP by Robert Lemons

The funny thing about this vacuum interrupter. It makes a "whistling" sound every time the hose nozzle is turned on and off. There is also a constant whistling noise when the water is flowing at low volume. This came as a surprise to me as no one else mentioned this "feature" in their reviews. My guess is that the whistling sound is caused by the rapid oscillating motion of the valve as it tries to respond to the low pressure in the hose by vibrating back and forth. I bought two of these and only tested one, so maybe the one I'm testing is defective. If I find out that the other one doesn't make that noise, I'll see if I can get the first one back. However, despite the whistling noise, this item breaks the vacuum like it should. So I wouldn't let this rating put me off buying it unless you're worried about the possibility of it whistling. It's not a loud whistle anyway, but when you're around the sound definitely gets your attention.