[LazyPup]

YOu stated that you have other floor drains so there should not be any long term problem with affixing a temporary cover, so long as that cover can be removed in the event of water on the floor.

The common problem with floor drains is that they dont get used, therefore the water in the traps evaporates. The permanent solution and the one most often used in new construction is to install trap primers. A trap primer is simply a small diameter piece of tubing attached to another water source to periodically feed a small quantity of water into the traps.

There is a simple trick that will aid your problem. About every two or three months pour a couple quarts of water into the floor drain. That will fill the trap, then pour a 1/2 cup of ordinary cooking oil into the trap. The oil will float on the water and will retard evaportion.