I'm trying to blowout sprinkler system for winter and have an issue with the Bonnet/Poppet sealing when air is pushed thru. the poppet remains open and won't close. What am I doing wrong here? I have a Febco 765DBV 3/4" Pressure Vacuum Breaker. Ball valve to house closed and valve to sprinkler system open. 1 of the small outlet closed and other open to allow air in from compressor. I turn on compressor and start pushing air thru at around 40 psi and increase with no luck. Any ideas?
Can I just re move bonnet/poppet and seal the top using some sort of closed top large screw?