Machine safety is a crucial thing as far as industrial production environment is concerned. As it is the responsibility of the employer to ensure safe working environment to the workers, adequate measures needed to be taken for machine safety at the first point. There are various mechanisms now used for machine guarding and safety administration, among which trapped interlocking is the most reliable and foolproof system used for long.
Trapped key interlocking
In trapped key interlocking, there is a combination of locks and keys, which practice a sequential control method to ensure safe operation. This mechanism is now widely used to ensure safe access to dangerous machine parts, power access points, and heavy-duty equipment at industrial settings. Visit website for more information.
Invention of trapped key system
Trapped key interlocks were first used by French Railway back in 1890s, which was then used for track switching. James Harry Castell and R. L. Kirk developed this system, so it is often referred to as Castell” and “Kirk” interlock systems. From then, trapped key interlocks started to be used in various industries like electrical, petroleum, power sector, chemical plants as an excellent measure of occupational safety.
Trapped key interlock operation
There is a sequence of operations in trapped key system with a transfer of key logic to enable or disable a machine. The keys are either trapped or released in a predetermined order. Say for example, there will be a key to isolate a circuit breaker, which is the same key needed to be released and put in to the access gate to get into a high-risk area. The key will be trapped until the gate is closed. The safety key can be released from the access lock, which ensures that the gate cannot be closed until the key is returned. This logic ensures safety and eradicates any chance for manual error.
A basic trapped-key interlock system will consist of a lock cylinder that operates a sliding bolt. It is assembled in a housing, which are of various styles in different applications. The sliding bolt can prevent operations of the switch when extended. There are many variations of trapped key interlocks exist. The significant feature making trapped key system unique is that the key is held or trapped in a single position of the lock. Releasing the key first can make the device safe and the interlocked device cannot be restarted until the key is returned to its former place. Get more details on CPR SafeInd and be updated with the latest guarding machines.
There are some complex sequences also used in the modern-day trapped key systems, which use key exchange blocks allowing alternative sequences. The key exchange blocks will only hold or release the key without any interlocking bolts. Some interlock system also may have electrical solenoids, which hold the key as the electrical circuit gets interrupted.
Trapped key interlocking application
Now trapped key technology is applied to almost all industries where the power sources needed to be deactivated before accessing a machine. The below sequence can be used for planning an ideal key interlocking scheme.
- First identify the energy sources and hazard areas (electricity, heat, radiation) to be isolated.
- Identify the access points and type of access. Clicking here for more explanation.
- Identify the part or full body access doors with or without personal safety keys to be prevented from accidental lock in
Once an initial evaluation is done, an adequate trapped key interlocking system can be implemented and tested for perfection before activating.