Another thread got me to thinking of a problem we've run into regarding flushing out spray pop-up zones. We've had to make a change in our flushing of spray pop-up zones after new installs since we've switched to the Toro PRX body/sprinkler. This has a pressure regulating valve and x-flow valve (shuts down water if nozzle/filter is removed) built into it. If we just slap the entire sprinkler head onto the swing joint, level and compact and then try and flush the zone out through the flush caps several of the sprinklers will clog at these internal valves from the normal debris (PVC burrs, glue, etc.) We've had to go back to the old method of either blowing out the zone through the swing joints only or removing the guts from the buckets and then flushing out. Once we've done this we can install the sprinklers, set them and then blow out through the flush caps if we so desire. This problem is so prevalent that I've actually had to write this procedure into our installation specs and details which I'm in the process of updating and adding all sorts of neat CAD installation drawings.