There is a gasket that sets against a sealing surface when the back flow device is pressurized. Make sure this sealing surface in clean and free of debris (sand, etc). If the sealing area is clean, you need a new gasket. Write down the model number and take the information to a irrigation supply house. They might stock a replacemet. If not they can order a replacement.

because of freezing temps here in the Houston area in the last couple of days, I was informed by a neighbor, that there was water gushing out of the top of the watts b/flow preventor for my irrigation system.....I had wrapped all my pvc pipes for the separate zones and the b/flow preventor itself but not knowing a lot about the process of taking preventative mesaures against freezing, since we do not have that kind of situaton all the time, I did not close off the main supply valve to the b/flow preventor--AND for some reason, I had closed off the valve AFTER the b/flow prevtr....and I did not open any drain valves, as there are only the two ports which have little plastic caps on them....I finally closed off the main supply valve, put the valves which are before and after the b/flow preventor in an angle at 45 degrees and opened one of the slots with a screwdriver at an angle as per some instrs I found on the internet about these types of installations.....can u tell me if the b/flow preventor is possibly damaged since the water pressure was against it ??...also although the shut off valves on the zone lines were shut off and insulated, they are stuck now and cannot be opened....I am guessing wate got in each one and it is frozen, preventing the opening of them...Please Help me !

Terry,

I don't really think i can help you since I can't see the problem for my self and your explanation is slightly confusing.
What did you mean by a neighbor saw some water gushing. That means it wasn't frozen, but what did you see first hand? I would suggest shutting off the main valve, drain the BFP and wait for troubleshooting in warmer weather. I doubt the BFP is damaged. The Watts BFP are pretty sturdy. JMHO Aloha