Been barbecuing a lot this summer? Is your propane tank running low? You just might be in for a surprise at refill time! As of April first of this year, all propane tanks must have a new type of ?fill? valve fitted with an overfill-prevention device. Older LP tanks -- those made before September 1998 -- were too easy to overfill, and about 600 a year exploded or caused fires. So the national fire prevention agency and the consumer production safety commission teamed up to pass this new law concerning propane tanks. Now, unless the LP tanks have the new valve, by law they cannot be refilled. Wondering which type you've got? New tanks with overfill-protection-device valves have a triangle- shaped valve handle on top, and an OPD label on the front. Older types have a round handle with five spokes. So if you weren't aware of this new law, better plan ahead. Otherwise you might be out of both LP gas and luck. And that's the On The House Tip for today.