I am looking for a manufacturer of a vacuum break used to prevent back flow the line from the basin to the pool in a negative edge. Thanks.
correction, I am looking for a air relesaf valve not a vacuum break. Thanks
You may be able to use a vacuum breaker made by Helicol. Part HC-121B. But it has to be installed above the edge pool
You are looking for a vacuum relief valve. When the lower pool is pumped up to the upper pool this drives the waterfall / negative edge. The line is under pressure when it is going. When it stops (power outage?) the line can provide a wonderful siphon which will dump the upper pool into the lower pool. A vacuum breaker, set in a vertical pipe that is above the water in the upper pool will allow air to suck in and break the siphon. It needs to be on the pressure side of the pump that drives the edge. I got a nice one at Reeves Wideman Plumbing Supply, in Lenexa, Kansas. A 3/4" or 1" will do for a 2" plumbing line.
An air relief valve is used to get air out of the top of a 7" commercial filter. They typically get dirty and are a problem.