ANSI/ASSE Z244.1-2016 The Control of Hazardous Energy Lockout, Tagout, and Alternative Methods
When writing the latest edition of the Lockout Tagout standard The American National Standard Institute included examples of practical and useful applications of alternative risk reduction methods. Trapped Key is an example of such a method and is explored in more detail in this article. Certainly, access to ANSI/ASSE Z244.1-2016 is a must-have for factory and maintenance managers across the United States looking to implement Lockout Tagout procedures.
Employers are often faced with difficult decisions when employees do not follow Lockout Tagout procedures. It’s Human nature to forget to apply every step of such procedures. Therefore, is it better to apply disciplinary actions for Lockout Tagout violations? Or look at enhancing procedures with a more engineering controls approach that cannot be forgotten or avoided?
Moreover, we can understand why Z244.1 includes examples of trapped key technology being used as an enhanced version of Lockout Tagout. In applications requiring mains isolation, a mechanical trapped key system can be used on access points to equipment. This ensures that full power isolation takes place before access is permitted.
Example 2: Alternative Risk Reduction Measures for Mains Isolation for Machines/Equipment within ANSI/ASSE Z244.1 includes the following recommendations on how to incorporate trapped key for main isolations:
First Recommendation
“Directly driving the contacts via a trapped key fitted to the shaft. This method would work on units that are small enough to allow the trapped key to drive directly.”
Second Recommendation
“Having a cam mechanism and bolt lock module for units that are too large for the trapped key to directly drive.”
Furthermore, Z244.1 includes a useful image of key switch and cam locking arrangements for readers to visualise an application to multiple access points.
Product Solutions
Fortress offers a variety of directly driven key switch variants up to 63A contacts, with a choice of contact arrangements. Typically those looking for three-phase isolation utilise a 4 Normally Open switch. For applications with larger switches or custom arrangements, keys can be mechanically interlocked into a switch handle arrangement in a Switch Control Unit (SCU).
In the case of retrofitting disconnects or hydraulic/pneumatic power already installed on equipment, the Fortress bolt module comes into play. A stainless steel bolt can be driven into a cam mounted on the power source, once the bolt is shot and the key is free it is impossible to return power. Consequently, the key can then be carried to a single access point or used for multiple access points via a key exchange.
Lock elements are available in die-cast or stainless steel construction while switch and enclosure variants can be specified based on customer requirements.
Product Solutions
Key Switches
Fortress offers a variety of directly driven key switch variants up to 63A contacts, with a choice of contact arrangements. Typically those looking for three-phase isolation utilise a 4 Normally Open switch. For applications with larger switches or custom arrangements, keys can be mechanically interlocked into a switch handle arrangement in a Switch Control Unit (SCU).
Bolt Module
In the case of retrofitting disconnects or hydraulic/pneumatic power already installed on equipment, the Fortress bolt module comes into play. A stainless steel bolt can be driven into a cam mounted on the power source, once the bolt is shot and the key is free it is impossible to return power. Consequently, the key can then be carried to a single access point or used for multiple access points via a key exchange.
Lock elements are available in die-cast or stainless steel construction while switch and enclosure variants can be specified based on customer requirements.
Products Mentioned in this Article
mGard - Trapped Key Range
mGard - Trapped Key Range
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Case studies
Enhancing Lockout / Tagout Procedures – How Do I Perform Full Power Isolation?
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