icon white trapped key

TRAPPED KEY
INTERLOCKS

What is a trapped key
interlock system?

The use of interlock systems is a proven method for predominantly mechanical securing of machines and processes.

The principle of interlock systems is based on the releasing and locking of uniquely coded keys in a predetermined sequence.

TüV certified
Ple according to EN/ISO 13849-1
200.000 unique key codes

Mechanical interlock systems

Our range of interlocks for mechanically securing machines

Do you need support?
Contact our specialists

The only interlock system that
is TüV certified to Ple

mGard is the product group of Fortress interlocks of mechanical key transfer systems (interlocks). mGard is the only interlock system on the market to be TüV certified to PLe (EN ISO 13849-1).

In addition, with more than 40 years of experience, Fortress Interlocks offers an extensive range of interlocks for virtually any machine safety application. ​

  • 200,000 unique keycodes with database management on end user
  • Door lock withstands up to 7500N pulling force
  • Use safety keys (with mandatory key removal) to prevent entrapment
  • Colour coding and laser engravings for identification purposes
  • Modular structure for easy modification and expansion of the system
  • Available in Mazac (zinc aluminium) or INOX316

Isolate

Isolation key A

Isolate

Isolation key B

Safety Key

Safety key a1

Safety Key

Safety key B1

How does an interlock
system
work?

Trapped Key Interlocks are an approachable way to safeguard your machinery.
Just use the following checklist.

  1. Does the machine have a run-down time or should the process not be interrupted (controlled shutdown yes/no)?
  2. Determine the number of access points to your machine
  3. Do all access points have to be open at the same time?
  4. Determine for each access point whether there is a risk of accidental lock-in (safety key yes / no)?
  5. Select the correct actuator / tongue for each type of access point (hinged door, sliding door or hatch).
  6. Select the right material for the environment (stainless steel or Mazac).
  7. Is it allowed for the system to be bypassed with a master key under certain conditions?

mGard key switches

Use our XMR or S safety key switch to isolate the installation. Turning the first key will engage the safety contacts and releases the key(s).

The released keys can be used to safely unlock doors and hatches. Only after all keys have been returned, the first key can be turned once again to restart the machine.

  • Suitable for usage in SIL3 (EN/IEC 62061), Category 4 (EN 954-1) and PLe (EN/ISO 13849-1) applications
  • 200,000 unique key codes
  • Robust INOX 316 casing or Zamac (zinc aluminium alloy)
  • Can be used as a coded safety switch in accordance with EN14119
  • Modular design for easy addition of doors/hatches
  • Flush mounted and surface mounted (IP67) versions available
DownloadsConfiguratorWebshop
xmr interlock key switch mgard
rvs coded key switch
Flush mounted or surface mounted

All Fortress Interlocks mGard key switches are available as a flush mounted or surface mounted variant.

In addition to IP66 plastic and a steel casing, the mGard key switches are also available in full INOX 316.

fortres s key switch
Laser engraving and colour coding

The robust CL locking mechanism is available in 200,000 unique key codings. In addition, the key codes and engravings are stored per end user to prevent issuing of duplicates.

Free of charge colour codings and laser engravings. They can be used for identification of key and lock.

coded key switch
Padlock lockable

In case multiple persons are to enter the protected area, or if a lockout tagout takes place, make use of dust covers that can be locked by means of padlocks.

Placing a padlock prevents the insertion of the key and thus prevents a machine restart.

ss interlock lockable key switch mgard

mGard lockable
key switches

Does your machine have a run-down-time or should the door/hatch not be opened at all times? Then use our SS solenoid controlled safety key switch for a controlled machine stop.

After energizing the solenoid, the keys can be turned and removed and then used again to open access doors or hatches.

  • Suitable for usage in SIL3 (EN/IEC 62061), Category 4 (EN 954-1) and PLe (EN/ISO 13849-1) applications
  • 200,000 unique key codes
  • Robust INOX 316 casing or Zamac (zinc aluminium alloy)
  • Can be used as a coded safety switch in accordance with EN14119
  • Modular design for easy addition of doors/hatches
  • Flush mounted and surface mounted (IP67) versions available
DownloadsConfiguratorWebshop
lockable key switch
Flush mounted or surface mounted

All Fortress Interlocks mGard key switches are available as a flush mounted or surface mounted variant.

In addition to IP66 plastic and a steel casing, the mGard key switches are also available in full INOX 316.

build in key switch controlled access
Modular

Both lockable and non-lockable key switches from the mGard product group are modularly structured.

The great advantage of this is that an extension module can easily be used for the expansion of the system, for instance if doors or hatches are added.

switch with coded key interlock
Request and reset

Add push buttons and/or status LED's toe as an indication, for access request or as a reset.

These function modules are available in flush mounted as well as surface mounted versions.

mGard
bolt locks

BM Bolt locks are used to lock isolating switches, valves, ball valves or level-operated switches..

By applying a cylindrical bolt, these energy sources can be mechanically locked in the "off" position, after which a key can be taken as a safety key or to be used for the engagement of another energy source or the opening of a door /hatch. 

  • ​Robust casing in Zamac (zinc aluminium alloy) or INOX 316
  • 200,000 unique key codes
  • Different sequences possible
  • Modular structure for extension with multiple locking mechanisms
  • Well resistant to moist, vibrations and dust
  • To be used in EX zones 1, 2, 21 and 22
DownloadsConfiguratorWebshop
bm interlock bolt lock mgard
fortress interlocks bmr bolt lock
Detection

The BMR cylindrical bolt lock makes it possible to check the position of the cylindrical lock through an integrated safety switch.

key interlock fortress interlocks
Key sequence

BM cylindrical bolt locks offer the possibility to determine the sequence of the keys yourself. For instance, key free = cylindrical lock applied or reversed functionality.

xm interlock key exchange unit mgard

mGard key exchange unit

XM Key exchange units or key exchange boxes are used when multiple doors have to be opened with one key switch or when multiple energy sources must be isolated before access to the installation can be given.

Suitable for usage in SIL3 (EN/IEC 62061), Category 4 (EN 954-1) and PLe (EN/ISO 13849-1) applications

  • 200,000 unique key codes
  • Robust INOX 316 casing or Zamac (zinc aluminium alloy)
  • Modular design to easy add lock mechanisms
  • ​Determine the key sequence yourself
DownloadsConfiguratorWebshop
modular mechanical interlock system
Modular design

With the XMA expansion module, lock mechanisms can easily be added to existing configurations, for example when adding doors or shutters.

XM key exchange unit fortress interlocks
Sequence locking mechanisms

Decide how many keys are trapped and released

When, for instance, initially two energy sources must be isolated before one door may be opened, the sequence is: 2 in = 1 out.

mGard door locks

DM and DMSK door locks are opened with the released access keys from the key switch.

As long as the door is open, the key cannot be removed, as a result of which the machine cannot be restarted.

Door locks are available in Zamac (DM), INOX 316 (DMS) and a fully hygienic INOX 316 variant (DMSK)

  • 7.500N tensile force
  • Suitable for usage in SIL3 (EN/IEC 62061), Category 4 (EN 954-1) and PLe (EN/ISO 13849-1) applications
  • 200,000 unique key codes
  • Head is rotatable in 4 steps of 90°
  • Can be used as a coded door interlock according to EN14119
  • Entirely mechanical (no cables needed)
  • Very robust design, resistant to moist, vibrations and dust
  • To be used in EX zones 1, 2, 21 and 22
DownloadsConfiguratorWebshop
dm door interlock mgard
robust door interlock mgard dm
7.500N tensile force

DM and DMSK door locks can resist a tensile force of 7,500N and are also very well resistant to moist, vibrations and dust.

The stainless steel head is rotatable in 4 positions of 90° so that the door lock can be used for all types of doors and hatches.

door interlock with handle
Different actuators

Choose from 5 different actuators.

Use the DM-H or DM-A handle actuators when large alignment tolerance is required, or for use on sliding doors. The DM-F fixed actuator is the perfect solution for doors or hatches with a small radius.

mechanical door interlock
Exposion proof and 316 stainless steel

DM and DMSK door locks are suitable for usage in almost all Ex zones.

The DMSK door lock is entirely made out of 316 stainless steel and, as such, suitable for hygienic and corrosive environments.

dm2 double door interlock mgard

mGard door lock
with safety key

DM2 and DMSK2 door locks offer the option of (mandatory) taking personal security keys to prevent the risk of entrapment.

Only if the door is closed and the safety key has been put back, the access key can be removed in order to restart the installation.

Double door locks are available in Mazac (DM2), 316 stainless steel (DMS2) and a fully hygienic 316 stainless steel variant (DMSK2).

  • 7.500N tensile force
  • Suitable for usage in SIL3 (EN/IEC 62061), Category 4 (EN 954-1) and PLe (EN/ISO 13849-1) applications
  • 200,000 unique key codes
  • The head is rotatable in 4 positions of 90°
  • Can be used as a coded door interlock according to EN14119
  • Entirely mechanical (no cables needed)
  • Very robust design, resistant to moist, vibrations and dust
  • To be used in EX zones 1, 2, 21 and 22
  • Available with different actuators
  • Optional: mandatory removal of safety key for extra safety
DownloadsConfiguratorWebshop
door interlock with safety key
Prevent entrapment

Safety keys prevent entrapment of employees in protected areas and enclosed spaces.

Take this key along with you to exclude the risk of a machine restart and locking of the door.

mechanical stainless steel door interlock
Combine wit amGard

Combine the mGard product group of trapped key interlocks using amGard Pro and amGard S40 for even more possibilities.

Because these product groups all make use of the same locking mechanism, combinations can easily be made.

entrapment danger interlock safety key
Mandatory key removal

In addition to the standard safety keys, with mGard it is also possible to choose a safety key with mandatory key removal (DMS2E).

Hereby it is only possible to unlock the door when the key actually has been removed.

GL interlock for valves sofis

Sofis interlocks
for valves

Sofis, formerly Smith Flow Control (SFC), valve locks are used to make sure that the operators use the correct sequence when manually locking and unlocking valves.

The valve lock or valve interlock is mounted on every individual valve in the process, to exclude human failure. Valve locks are available for valves with levers (QL lock) or handwheel valves (GL lock).

  • ​Determine the key sequence yourself
  • Detect optional key removal
  • Fits on every valve through an adapter set
  • Entirely mechanical (no cables needed)
  • To be used in EX zones 1, 2, 21 and 22
  • Version for handwheels (GL) and ball valves (QL)
Downloads
smith flow control ql interlock
Adapters for every type of valve

By using an adapter set, Sofis interlocks can be placed on any type of handwheel or ball valve.

The adapter is custom made and measured on site by our technicians to ensure it will fit.

sofis interlock iml actuator
Actuator operated valves

The IML valve lock is used to lock actuator-operated valves during maintenance.

The interlock is placed between the valve and the actuator and can easily be operated with a coded key.

sfc ql ball valve interlock
Lock in 2 positions

Determine the sequence of the key removal of your valve locks; release of the key in open or closed position. This will prevent two valves from being open at the same time.

We are
here to help

Contact one of our technical specialists or sales engineers

Sales engineer Marco Heijkoop small

Marco Heijkoop

Sales Engineer

marco.heijkoop@usp-safety.com
Sales engineer Rick de Jonge small

Rick de Jonge

Sales Engineer

rick.dejonge@usp-safety.com
Rob Voordendag small

Rob Voordendag

rob.voordendag@usp-safety.com
Robert van de Ven small

Robert van de Ven

robert.vandeven@usp-safety.com

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