We were called by an existing customer who needed a Yale lock fitted to an internal door in a care home. After a bit of thought I fitted a Yale 91 lock to that door later that day. A Yale 91 isn’t often used, but we carry a few in stock as they are a bit different and come in handy in some situations. A Yale 91 lock body cannot deadlock to stop a key from unlocking it. It can however hold the latch back to stop the door from locking if it closes.
On a Yale 88 or 84 you can slide the button on the Yale lock body to stop the latch from being pushed back in. You can’t do that on this Yale 91. We needed to give full assurance that a key would always unlock the door in this instance and so couldn’t fit any of the other models.
Just to make the job a bit more interesting – as it was an internal door the door opens outward (Not like a standard front door). And so the fitting of the lock takes a little bit longer and a bit more thought 🙂