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Old Backflow Preventer

My backflow prevention device failed over the winter (nice large split, as you can see). I checked with the local city, and they won't let me replace like with like, so I'm going to install a Wilkins 720A pressure vacuum breaker instead; here's my proposed design (the unions are so that I can remove the PVB in the winter). Inflow is on the right-hand side, and the sprinkler system will be on the left. This is culinary water, but not connected to the house. Proposed PVB design Here's my question; as you can see in the photograph, the underground input and output are on black PVC (I think) pipes, 1". Can I use a similar method of connection (Jubilee/hose clips) to connect to the 1" schedule 40 pipe, or is there something else I should use? If I do use the hose clips, can/should I lose the box and bury the pipes (for support)?

I have to get this inspected, and I want to do it correctly the first time, rather than get rejected for something silly like a pipe connection.

  • The black sprinkler pipe is probably HDPE and not PVC so you need a different connection method than with PVC. You might check with a local sprinkler supply company that can give you the right option for local requirements. – jwh20 Mar 3 at 18:13
  • @JWH20, I agree and this should be an answer, the hose clamps are a sure ID that it is not pvc. – Ed Beal Mar 3 at 18:20
  • It's kind of hard to guess what will pass inspection without knowing whose rules are being inspected against. – Jasen Mar 3 at 19:18
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The black sprinkler pipe is probably HDPE and not PVC so you need a different connection method than with PVC.

Your best bet is to check with a local sprinkler supply company that can give you the right option for local requirements. Around here they use hose barbs and hose clamps but other places may require different connectors when transitioning from HDPE to PVC.

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  • Thank you. How about burying those, or do they need to be in a pit? – PeteCon Mar 3 at 18:43
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    Whether required by code or not, you want to make sure that all your connections are in a box so they are easily accessible to inspect and repair. You might think you'll remember where they are but I assure you that you won't and it will entail a lot of digging! – jwh20 Mar 3 at 19:04

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