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ANTI-LIGATURE Mechanical 1-way SOS lockset (PR1)

Suitable for low-risk doors where tampering is unlikely, our anti-ligature mechanical 1-way SOS lockset provides just one override method – key override.  The patented direct mechanical override means the key and turn/pull operate independently – allowing staff to unlock the door, even if service user holds the turn/pull.

Because determined barricades cannot be overcome, this lockset is ideal for staff areas or to provide a 'lock-off' function on doors.

NB: Our 1-way SOS (Staff Override System) was previously referred to as our classic override option. 


Key always dominates the turn/pull

With the patented direct mechanical override means, 1-way SOS addresses the limitations of comparible override systems – giving peace of mind and ensuring rapid access.  For example, clutch cylinders are susceptible to wear and tear and can malfunction, trapping service users in their rooms, and geared cylinders – which rely on a key to disengage the internal turn/pull – and can be over-rotated to delay access to the room.


1. Key

The lock and the internal turn/pull operate independently, so the key always dominates. It’s a direct mechanical override, so there’s no geared cylinder to disengage the turn/pull or clutch mechanism involved.

Lifeline option

Available with Lifeline closed keyway

We believe prevention is better than cure. 

That's why our 1-way SOS locksets are available with Lifeline closed keyway locks.  Operated by staff-only keys, they’re designed to stop foreign objects jamming the keyway – minimising the chances of a determined barricade attempt and reducing the need to use the emergency override procedure.

Plus locks using Lifeline can be unified, providing one-key access for staff to operate all the locks – door, vision panel, anti-barricade stop and window – with a single key.  This eliminiates the complexity of chosing the right key in stressful situations.


Limitations of alternatives


Clutch cylinders

Clutch cylinders

When a service user holds the internal turn/pull to create a barricade, the catch is designed to slip at a higher torque. Operating on a spring and ball-bearing mechanism, the key then turns and unlocks the door.

Over time, however, doors moveexpand or distort, limiting clutch effectiveness and making entry times longer in stressful situations.

Wear and tear can also cause the clutch to permanently slip – trapping service users inside and causing distress and fire safety issues.

Geared cylinders

Geared cylinders

When the key is put into a geared cylinder, it mechanically disengages the internal turn/pull, allowing the door to be opened.

However, service users can easily rotate the turn/pull past its maximum closed position, preventing the key fully engaging. Although the key can eventually be forced home, it can damage the cylinder and the key may snap, causing risk of injury and prolonging the barricade because of a blocked keyway.

Issues also arise in rehabilitation or step- down units, where service users may have their own key. This can be inserted into another service user’s lock, disengaging the turn/pull and locking them inside, resulting in anxietydisruption and fire safety risks.


Designed by Gilling Dod Architects, Ancora House is an award-winning 30-bed CAMHS unit built round an aluminium curtain wall structure.  The en-suite rooms needed simple, practical and safe anti-ligature locksets that were also consistent with window and door handles. The solution was our 1-way SOS locksets and standard pull handles. 

Safehinge Primera locksets and handles were also fitted elsewhere throughout the two-storey facility. 

Lockset builder



1-way SOS locksets should only be used on doors where a service user is always unsupervised or situations where they are unlikely to be able to create a barricade or hostage situation.

Because of the vital access that locksets provide, selecting the right lockset, lock option, and handle and backplate for your project is critical.  That's why we've created our lockset builder to guide you through the selection in four simple steps.


Step 1: Lock options

Step 1: Choose the most suitable lock option

1-way SOS locksets are compatible with all our mechanical application types, giving you the option to choose the most suitable lock options for the door. 

For example, riser doors and cupboards are best suited to the '16 Service Riser' options because there's no handle or lock on the inside.  While dispensery doors benefit from the '66' or '86', which automatically lock when the door closes – increasing security and providing peace of mind. 

The full range of available lock options for the 1-way SOS lockset are below.

Step 2: Pull-handle options

Step 2:  Choose the handle

Robust and independently anti-ligature tested, our handles are tried, tested and proven in the Mental Health environment.  Using the Door & Hardware Federation specification – TS001 – our handles pass at the highest level in their respective categories: A4 for anti-ligature resistant in all directions; B4 for anti-ligature resistant vertically downwards.

So in high-risk environments, only A4 rated handles should be used – like the Pinch Grip or Turn/Pull.

In situations where manual dexterity of service users is the primary concern, the B4 rated handles can be used – like the Elephant's Trunk or Oryx – which make door opening easier for those with lower strength.

Our range of compatible handles is below.

Step 3: Back-plate options

Step 3:  Choose handle back-plate

Handles and locks can be mounted separate or unified back-plates, depending on the situation.  And, in the case of retrofittting, larger back-plates can be specified to cover mounting holes from the previous installation.


Step 4: Turn-handle options

Step 4:  Choose the turn-handle

The Turn/pull handle is supplied as standard, but some locks can be upgraded to the Oryx lever – which is more suitable where manual dexterity is the priority over ligature resistance.  Get in touch for details.

Glasgow office

Level 4, Skypark 3
14 Elliot Place
G3 8EP

t: 0330 058 0988

Blackpool office 

Unit 8 Bankfield House
250 Bristol Avenue

e: info@safehingeprimera.com


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