1 Breakages are less as the boards are much tougher and have fibers reinforcing in them. 2  they damage less easy from general wear and tear in everyday use in a home or office. 3  It offers slightly better acoustics than standard board.  It is a superior product in case of fire.
It is normal for the solenoid to make noise, it clicks when the valve is turned on or off. It also is normal for a very soft buzzing sound to be heard when the valve is activated, but you should not be able to hear it unless you put your ear near it. If you can easily hear it buzzing, that is not normal.
The SL valves function to stop blood from flowing back into the ventricles during the 2nd heart sound. So the first beat you hear are the AV vales closing shut (they shut rapidly and hard so this sound is louder) then the second beat are the SL valves slowly(relatively so) closing shut, producing a quieter sound. Source(s): My Flying Toast OWNS Yours! Â· 4 years ago.