Came across this at Home Depot today as a way to possibly connect the Intex threaded strainer connectors with minimal modification directly to 1 1/2" PVC at poolside to eliminate the need for plunge valves:
NIBCO 1-1/2 in. PVC DWV Trap Adapter (Male)
http://www.homedepot.com/h_d1/N-5yc1v/R ... ogId=10053
Mueller Streamline 1-1/2 in. PVC Sch. 40 Pressure Slip x FPT Female Adapter
http://www.homedepot.com/h_d1/N-5yc1v/R ... key=Search
First of all, I think the linked image is the correct adapter (Home Depot has the wrong UPC code on the part I bought, but I'm pretty sure I've linked the right one. The easy way to tell is that the threads on the Trap adapter should screw into the 1 1/2" FPT Female Adapter on the second part. As long as they do this, you are good to go).
Install the threaded strainer connector into the pool wall in the normal manner. Take the nut and vinyl washer off the PVC Male Trap adapter and toss them in the garbage - they aren't needed here. Make a flat compressible rubber washer (maybe a quarter inch thick and slightly taller than the Trap adapter middle ridge) to fit around the slip connector end of the PVC Male Trap Adapter at the middle ridge, then stick the slip connector into the back end of the Intex threaded strainer connector so that the rubber washer is between the Intex strainer connector and the PVC Trap adapter (i.e. the threads on the PVC Trap adapter will be sticking out the back of the Intex strainer connector. It will actually fit just a tad loose, but the raised ridge around the middle of the Trap adapter is almost exactly the same height as the opening in the back of the Intex strainer connector. You could probably actually glue the part directly to back of the the strainer connector, but the part fits just loose enough that I'd be concerned with how the connection would hold up under pump pressure. Gluing would also create problems with future disassembly of the joint). Stick the Intex split nut from the plunge valve over the threads of the Male Trap adapter rubber washer and screw it tightly onto the threads of the Intex threaded strainer connector just like like you normally would to put a valve on the strainer connector (it should squeeze the homemade washer tight and create a good seal). Finally, apply a liberal helping of pipe dope to the PVC Trap adapter threads and screw the 1 1/2" Schedule 40 Pressure Slip female adapter onto the PVC Male Trap adapter threads. This will leave you with a slip PVC connection directly to 1 1/2" PVC.
I've dry fitted it using a spare Intex strainer connector and think it should work well.
I recommend using the split nuts from the plunge valves to put it together over the single piece hose nuts as everything fits pretty tightly. Future disassembly of the connection is made easy by the ability to simply take the bolts out of the split nuts to release the connection at the strainer connector threads without having to take off the Pressure Slip x FTP female adapter.
I'm still struggling with my sand filter issue and other issues at work, so it will probably be a while before I can get around to actually trying this. If anyone tries it before I get to it, please post back and let me know how it worked out.
In theory, the same parts could be used with pipe nuts (solid or split) to pipe all the other connectors to 1 1/2" PVC given that most of the joints away from the valves have o-rings and seals which would allow you to create the connections without leaks - you'd probably have to cut the slip connector off the Trap adapter at the raised middle edge, though. The Carlon electrical conduit connector is probably better for this unless you can't get the ones you need.