Had a very disheartening experience with the owner of this business today: "Mark".

I've done business with them in the past and was calling for support on an issue I unearthed. I told him I believed his process for blowing out my irrigation lines was incorrect, according to information I was turning up on multiple websites, videos and in certain articles.

He disagreed profusely with me, stating that there is no issue with blowing compressed air through the test $#*! / side port of a PVB (pressure vacuum breaker) backflow device at the head of an irrigation system.

www.hunterindustries.com states this:

"COMPRESSED AIR SHOULD NOT BE BLOWN THROUGH ANY BACK FLOW DEVICE. To start the blow out, shut off the irrigation water supply and, with the compressor valve in the closed position, attach the air compressor hose to the fitting. Activate the station on the controller that is the zone or sprinklers highest in elevation and the furthest from the compressor. CLOSE THE BACKFLOW ISOLATION VALVES."

SOURCE:
Https :// www.hunterindustries. Com/winterizing-your-irrigation-system#:~: text=Compressed%20air%20should%20not%20be, compressor%20hose%20to%20the%20fitting.

https://extension.colostate.edu/ states this:

"Pressure Vacuum Breaker (PVB) or Reduced Pressure (RP) backflow prevention devices must never be blown out with compressed air. THE RUBBER SEALS INSIDE CAN EASILY MELT FROM THE HEAT OF THE AIR."

SOURCE:
https://extension.colostate.edu/topic-areas/yard-garden/home-sprinkler-systems-preparing-your-sprinkler-system-for-winter-4-719/

The customer is always right. This was poor business conducted today. Sure, Mark, you can input compressed air through a backflow prevention device but you cannot prove to anyone this practice is not damaging units over time. It's best practice to install a blow-out port downstream of any backflow device so the unit itself can be effectively isolated and protected by upstream valving.