Last week I received a call that wasn’t completely unexpected. The shear locks that I had specified for a recent project had been installed and “sounded like a gunshot” when they were locked or unlocked.
In my defense, I only specify shear locks under duress. I always warn prospective shear lock users about the noise associated with the steel armature being drawn across the gap at the top of the door and hitting the electromagnet in the frame. Most security consultants won’t use shear locks because everything has to be perfectly aligned for the locks to get a secure bond, and misalignment of the doors over time will reduce the security of the opening.
In this case, the doors were on the most high-profile space, the executive floor elevator lobby and the boardroom. I didn’t want to add insult to injury but I asked if I could videotape the “gunshot” so the next time I try to explain the sound, I’ll have back-up. The architects graciously allowed me to schedule a site visit.
The elevator lobby doors had already been retrofitted with direct-hold mag-locks which are MUCH quieter, but since the boardroom will only be locked and unlocked occasionally, the shear locks will remain. There isn’t much to see on the video below, but you can hear the locks locking and unlocking as I push the release button. Shear locks have their place, but make sure the noise and alignment issues won’t be a problem before specifying them.
I thought it might also be helpful to see the difference between direct-hold mag-locks installed in a full-width header (as originally specified for other floors), vs. the standard housing (where mag-locks were retrofitted and center pivoting glass doors will not accommodate the full width header). Here they are: