In part one of this feature, we introduced the shotbolt – a solenoid actuator – as the workhorse at the heart of most straightforward electric locking systems. Shotbolts remain at the core of most sophisticated electric locking solutions as well. But they are supplemented by materials and technologies that provide characteristics suited to specialist security applications. Here we look at some more demanding electric locking applications and contemporary solutions.
Preventing forced entry
Where the end of the shotbolt is accessible, the electric holding force can be overcome by physical force. That’s why anti-jacking technology is now a frequent feature of contemporary electric solenoid lock actuators.
Anti-jacking, dead-locking or ‘bloc’ technology (the latter patented by MSL) is inherent to the way the locking assembly is designed to suit the requirements of the end application. The patented bloc anti-jacking system is highly effective and incorporated into many MSL shotbolts deployed in electric locking applications. The bloc technology uses a ring of steel balls in a shaped internal housing to physically jam the actuated bolt in place.
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| A range of marine locks is widely used on Superyachts for rapid lockdown security from the helm |
Real life applications for MSL anti-jacking and bloc-equipped shotbolts include installation in the back of supermarket trucks to secure the roller shutter. Once locked from the cab, or remotely using radio technology, these shutters cannot be forced open by anyone with ‘undesirable intentions’ armed with a jemmy.
A range of marine locks is widely used on Superyachts for rapid lockdown security from the helm. While anti-jacking features are an option on these shotbolts, consideration was given to the construction materials to provide durability in saltwater environments. Marine locks use corrosion-proof stainless steel, which is also highly polished to be aesthetically pleasing to suit the prestigious nature of the vessel while hiding the innovative technology that prevents the lock being forced open by intruders who may board the craft.
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| Rotary and proportional solenoids sound unlikely but are now common |
A less obvious example of integrated technology to prevent forced override is a floor lock. This lock assembly is mounted beneath the floor with round-top stainless-steel bolts that project upwards when actuated. They are designed to lock all-glass doors and are arguably the only discreet and attractive way to lock glass doors securely. In a prestigious installation at a historic entranceway in Edinburgh University, the floor locks are remotely controlled from an emergency button behind the reception desk. They act on twin sets of glass doors to quickly allow the doors to close and then lock them closed with another set of subfloor locks. No amount of stamping on or hitting the 15mm protruding bolt pin will cause it to yield, thus preventing intruders from entering. Or leaving!
Explosion proofing
In many environments, electric locking technology must be ATEX certified to mitigate any risk of explosion. For example, remote electric locking is used widely on oil and gas rigs for stringent access control, general security and for emergency shutter release in the event of fire. It’s also used across many industrial sectors where explosion risks exist, including flour milling, In many environments, electric locking technology must be ATEX certified to mitigate any risk of explosionpowder producers, paint manufacture, etc. This adds a new dimension to the actuator design, demanding not only intrinsically safe electrical circuits and solenoid coils, but the careful selection of metals and materials to eliminate the chance of sparks arising from moving parts.
Resilience under pressure
The technology boundaries of solenoids are always being pushed. Rotary and proportional solenoids sound unlikely but are now common. More recently, while not directly related to security in the traditional sense, proportional solenoid valves for accurately controlling the flow of hydrogen and gases now exist. Magnet Schultz has an extensive and somewhat innovative new range of hydrogen valves proving popular in the energy and automotive sectors (Fig. 2-6). There’s a different kind of security risk at play here when dealing with hydrogen under pressures of up to 1050 bar.
Bio security
Less an issue for the complexity of locking technology but more an imperative for the effectiveness of an electric lock is the frequent use of shotbolts in the bio research sector. Remote electric locking is commonplace in many bioreactor applications. Cultures being grown inside bioreactors can be undesirable agents, making 100% dependable locking of bioreactor lids essential to prevent untimely access or the unwanted escape of organisms. Again, that has proven to be topical in the current climate of recurring coronavirus outbreaks around the world.
More than meets the eye
In part one, I started by headlining that there’s more to electric lock actuation in all manner of security applications than meets the eye and pointed out that while electric locking is among the most ubiquitous examples of everyday security, the complexity often involved and the advanced technologies deployed typically go unnoticed.Integrating the simplest linear actuator into a complex system is rarely simple
For end users, that’s a very good thing. But for electro-mechanical engineers designing a system, it can present a challenge. Our goal at Magnet Schultz is to provide a clearer insight into today’s electric locking industry sector and the wide range of locking solutions available – from the straightforward to the specialised and sophisticated. Integrating the simplest linear actuator into a complex system is rarely simple. There’s no substitute for expertise and experience, and that’s what MSL offers as an outsource service to designers.
One benefit afforded to those of us in the actuator industry with a very narrow but intense focus is not just understanding the advantages and limitations of solenoid technology, but the visibility of, and participation in, emerging developments in the science of electric locking. Knowing what’s achievable is invaluable in every project development phase.
