On Sunday, January 13, 2019 at 1:33:48 PM UTC-5, Davej wrote:
On Saturday, January 12, 2019 at 10:34:21 PM UTC-6, Ed Pawlowski wrote:
On 1/12/2019 10:14 PM, Davej wrote:
I seem to see three types of backflow preventers:

1. valve + vacuum breaker
2. double-check-valves
3. double-check-valves + pressure regulator

If I don't need or want pressure regulation how do you compare 1 vs 2 above?

This would be for lawn irrigation or water-powered sump pump.

Examples:

https://www.homedepot.com/p/Zurn-3-4...720A/100197627

https://www.homedepot.com/p/Febco-3-...-850/205888731

https://www.homedepot.com/p/Apollo-3...4A2F/307723094

If you've not done so already, check your local codes to see if they
specify one type. Some do not allow double check, others do.

Will do. I think the vacuum-breaker approach seems more logical.

That's what's used here, NJ for irrigation connection. I would bet it's
probably part of the widely used national plumbing code.