Guardmaster Prosafe’s (Wigan, UK) new solenoid key release units can be incorporated into virtually any process or access control system to ensure its safe operation. Constructed from 316L stainless steel, the key release units ensure the electrical isolation of machinery, allowing safe access into machine enclosures. Although designed primarily for use with Guardmaster Prosafe’s mechanical key interlock systems, the single or multiple direct-drive solenoid key release units can also be used in conjunction with other control equipment such as PLCs, or with dedicated stop motion or failsafe timers on machines with run down cycles. Moving machinery such as food processing, packaging machines and robot welding lines are particularly dangerous and in these applications the use of the key release unit with a dedicated timer can help to ensure that all movement has stopped before the operator can enter the enclosure. The key to the greater safeguarding provided by the solenoid release unit is a design that allows a trapped key to be removed only when a signal is given to an internal solenoid locking mechanism. On receipt of this signal the previously trapped key can be removed and used in the next sequence of operation. This could be to provide access to a gate, or gates, directly, or more often to initiate a further operation, such as the release of multiple keys in a key exchange unit. In all cases, however, once the key is removed the solenoid cannot return to the locked position even if power is removed.