Powered Gate Myth Buster #4

Non-contact presence detection negates the need for testing

Non-contact presence detection systems are gaining popularity in the powered gate industry.  Whilst this technology can provide a considerable improvement in safety for vulnerable users and provide effective solutions for some of the more complex hazards, it also provides an opportunity for misunderstanding.  Some systems have been put into service using light grid or laser scanner technology that are clearly unsafe.

A system is not safe simply because a particular device has been used, it is only safe when that device has been proven to provide acceptable levels of safety, in short, testing is required.

Before we get on to testing the device as installed however, it is important in the first instance to ascertain that the device itself is in fact appropriate for use in this environment.  Devices for use on powered doors, gates and barriers must be supplied with a Declaration of Conformity with the Machinery Directive 2006/42/EC from the device manufacturer.  This point is critically important.  There are many devices that look to be appropriate or suitable but are not in fact rated as safety components in the meaning of the Machinery Directive.  Many activation devices or supplementary photo beams to be used with force limitation fall into this category.  Next, according to EN 12453 (2001 & 2017) the device must be in full conformity with EN 12978, sensitive safety devices for doors, gates and barriers.

Having obtained the correct specification device, and have installed it correctly, and have ensured that we have wired it up to a compatible test circuit such that it will achieve at least category 2 as installed (it is not enough that it is itself rated to at least category 2), we can consider the appropriate commissioning tests.

Testing of these devices is done with specific rigid material test pieces:

1. a rigid box measuring 700mm x 300mm x 200mm, pained with light reflecting finish on 3 surfaces and light absorbing finish on the other 3, and
2. a rigid material cylinder measuring 50mm diameter and 300mm long, finished half and half in light absorbing and reflective finishes.

The test pieces are used essentially as ‘crash test dummies’ or ‘disposable probes’ as, if during the tests the test piece is able to become crushed, sheared, drawn-in or impacted by the gate, the test has failed.  The overall premise for use of these devices, according to EN 12453, is to prevent all possible contact with hazardous movement.

Once testing is complete, the results of the tests should be recorded on a test report and retained in the appropriate technical (new systems) or maintenance (existing systems) file.

More detailed explanations of how to conduct the tests on various gate configurations can be found in DHF TS 013:2021.

Nick Perkins

dhf  Senior Training and Compliance Officer