For example: if it's a water-purifier; install a plastic barricade around the unit with a chained door and padlocks.
Each department has a representative called a "gatekeeper" that holds the key to one of the padlocks.
And there are TWO logbooks to be kept for all use of the equipment:
one by the user, and one by the "gatekeeper" of their department.
When someone wants to use one of the pieces of shared equipment, they have to go to their department's gatekeeper
and get the key. A log entry must be created for "key checkout".
To access the equipment, the user now has to visit the room, when the equipment is not in use ---
open the logbook in the room, inspect the tamper-evident seal on their department's padlock:
write down the date, time, and seal number. break the seal. use their department's key to open it and remove the barricade.
Now, they can use the equipment.
When they are done, they must close the door, reaffix and lock their department's padlock,
and make the entry in the logbook.
Call the gatekeeper. The gatekeeper will come visit the equipment room, verify that the equipment is in good working order:
note the date and time in the gatekeeper log book.
Verify that the proper entries have been made in the equipment use logbook
Affix a new tamper-evident seal to their department's padlock, and write down the seal number in the gatekeeper logbook with "Key returned"
The user will sign the log entry, and the gatekeeper will return the key to the department's lockbox, and sign the entry.