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Trapped Key Interlocks

Fortress Interlocks mGard range is the premier range of modular robust trapped key interlocks for heavy duty applications. Trapped key interlocking is a tried and tested method of mechanically safeguarding dangerous machines and hazardous processes, and is suitable for use up to SIL 3 / Category 4. It is called "Trapped Key" as it works by releasing and trapping keys in a predetermined sequence. After the control or power has been isolated, a key is released that can be used to grant access to individual or multiple doors.

The principles of trapped key technology apply to all industries where it is essential that all energy sources are isolated before gaining access to machinery. The Fortress Interlocks mGuard trapped key range includes:

  • DM series of trapped key door interlocks designed in a modular series, so that you can have multiple access keys.
  • S / SE Isolator units - suitable for isolation or switching current and may be used to isolate power to machinery.
  • SS solenoid isolator units are used where the key / keys need to remain trapped until an electrical signal has been received.
  • ODL ‘key bank’ key release control units with an isloator switch, incorporates one or more rotary switches and any combination of trapped or freed keys.
  • XM series key exchange units are used to exchange one or more keys for a number of other keys. This device forms the link between isolation devices and access locks.

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