Sentric unites Castell, Kirk, Salvo, STI & Zonegreen

Our History

Each of our brands have been at the forefront of trapped key interlocking for over 100 years.

Take a look at our history and see how what started as a simple design to protect people and assets, turned into a globally successful safety solutions business.

Visual representing Sentric Group journey and history over time


Sentric announces it has acquired Zonegreen. Headquartered in Sheffield, United Kingdom, Zonegreen develops technologies, software and services that make working in rail depots safer and more efficient.  Zonegreen’s products are used by rail customers across the UK, Ireland and Australia.


KIRK, Castell & Serv Trayvou Interverrouillage becomes Sentric Group

The global SPS formed in 2016, becomes Sentric Group, consisting of three sister companies Kirk in the US, STI in France and Castell in the UK. Our mission is to unite the world’s leading brands, product innovations, and experts to protect people in safety by mitigating the risk caused by human error. As Sentric, we share Purpose, Vision, Mission, and Values which bring unity, clarity and direction to everything we do. 


Castell 100 Years Anniversary Logo with 100 years tagline

Castell celebrates its 100th anniversary.


Castell BSI ISO 45001 certification

Castell becomes ISO 45001 certified.


Castell logo

Serv Trayvou Interverrouillage and Castell develop a digital solution for truck key management integrating Salvo and SKM together in 2017.


SPS logo

The global leading group for interlock safety systems was formed back in 2016. It consists of three market-leading businesses, Kirk, Castell and STI, combining the expertise and high quality products of the three brands.


KIRK office since september 2014

In September 2014, Kirk moved operations and manufacturing to North Canton, OH, USA.


Castell's 90th anniversary in industrial safety

Castell celebrates its 90th anniversary.


Halma award for manufacturing excellence

Castell wins the Halma Manufacturing Excellence Award.


Halma plc logo

In 2011 Kirk Key Interlock Company LLC was purchased by the holdings company Halma plc.


Serv Trayvou Interverrouillage logo

In 2009, STI and HF Sécurité merge under the name Serv Trayvou Interverrouillage becoming the main safety interlocks company in France for the Industry & Manufacturing, Energy and Transport sectors.


Smart Key Manager (SKM)

STI launches the very first RFID access management system SKM and takes a step into the digital world and industry.


Salvo product range logo in 2005

Launch of new product range Salvo.


KIRK Business location in 1999

In December of 1999, Kirk Key Interlock Company LLC separated from ABB and was completely independent, moving operations to Massillon, Ohio, USA.


Mistura product range

Castell purchases new product range Mistura.


STI ISO Certification 9001

STI is certified ISO9001-2000, a must-have for quality assurance.


Castell BSI ISO 9001 certification

Castell UK becomes ISO 9001 certified.


Halma plc logo

Halma Group buys Trayvou and merges the French companies in 1987.


Castell Iso-Lok lockout tagout product range logo

Castell purchases Iso-Lok lockout tagout product range.


UK Health and Safety at Work Act

UK Health and Safety at Work Act.


Halma logo

Halma Investments Limited purchases Castell Locks Limited.


STI is a Halma Group Company

In 1962, Halma Group buys SERV.


SERV is established

Mr Barillet leaves Trayvou to establish the company SERV in 1961, the trapped key Interlocking business.


Castell padlock in 1932

Castell granted improvement to padlocks patent (patent number GB430168).


KIRK Manufacturing increases in 1932

In 1932, KIRK® trapped key interlocks were manufactured in Greensburg, Pennsylvania in the USA, as part of the Railway & Industrial Engineering Company which held the patent filed by R.L. Kirk.


R.L. Kirk signature

R.L. Kirk filed for his first patent “Safety Interlock for Electrical and Mechanical Equipment and Systems” in 1931 and Kirk became an authority in electrical safety.


Tavistock Square first Castell office

James Harry Castell establishes ‘Castell Locks.’


Castell's oldest recorded order

Castell’s oldest recorded order placed by leading UK engineering and heavy industrial company


James Harry Castell

James Harry Castell patents ‘Castell’ figure interlocking system to protect people during the electrification period in London.


Serv Trayvou Gold Award at 1900 World Exposition in Paris

At the 1900 World Exposition in Paris, Mr Bouré triumphed with a gold award for his invention.


Trayvou manufacturers interlocking devices

In 1895, Trayvou manufacturers interlocking devices for the manufacturing industry and the railway industry.


STI a first for interlocking

For the first time in the world, an interlocking system was designed in 1894.


Creation of the engagement lock by Trayvou

In 1893, Paul Bouré creates engagement lock devices to ensure train traffic safety.