If it has a 1/4" NPT thread, then yes.
NPT means that it has a tapered thread. It gets more narrow the deeper it goes. This way when you thread in something with the same thread, it will seal as it tightens. Always use teflon tape, though.
You will regularly find 1/8" NPT and 1/4" NPT taps at hardware stores. 1/2" is a bit too big. Most likely you have 1/4". Just take one of the fittings to the hardware store (Home Depot usually carries a 1/4" tap) with you and compare the thread on the fitting to the tap thread.
Also note that the 1/4" NPT tap and drill bit combo that HD sells was useless to me because the shank of the drill bit was too large to fit in my drill. They sell them seperately, too. And the seperate drill bit has a turned down shank to work in any drill.