Spare dump valve - confirming 3/4" pvc pipe plug?

On my last trip I managed to lose the dump valve cap. I used Roman’s sandwich bag/inflation bag solution[1] without incident, but now I’m looking for a more permanent replacement. I’ve read that standard 3/4 threaded plugs will work,[2] so I’d just like to confirm that folks are talking about something like this: http://www.amazon.com/dp/B008HQ7X22/ref=biss_dp_t_asn. Obviously the PVC plug doesn’t provide an easy way to tie the plug to the raft and prevent the problem from recurring, but I’m looking for something I can get at a hardware store before the weekend.

Thanks!

Nathan

[1] http://www.packrafting.org/forums/viewtopic.php?f=4&t=655#p2595
[2] http://www.packrafting.org/forums/viewtopic.php?f=16&t=836

The rubber O-ring on the valve cap is what is making the seal. The cap you described will work if you can find an O-ring that fits comfortably around the threads and seats on the top flange. Otherwise, you can use Teflon tape to seal the threads (bring a whole roll for a long trip), which is not ideal, but works!