Also online at: www.dijonline.co.uk 93 Automated Gates & Barriers THE door industry journal winter 2022 methods of providing the required safety, providing they are tested accurately and maintained in a safe condition”, says Nick. Force limitation must be tested using an annually calibrated force test meter that conforms to EN 12453 to ensure both force and reduction time are accurately measured to accurately verify that safety and compliance are achieved. Nick goes on to explain: “It is not possible to test all the areas of a gate system that rely on limited force for safety; some areas must be verified by analysis of the readings taken at the main edge”. DHF TS 013 on-site guide explains how to do this in sections 6.5.3 & 6.5.4. EN 12453 requires that, where automatic gates are protected by force limitation, they must also be equipped with ‘supplementary’ beams to reduce the probability that a person will be contacted by a force-limited gate. Nick explains that: “Although the beams are a mandatory requirement to limit the probability of contact, the primary requirement is to limit force wherever contact with a person is possible. Supplementary beams cannot provide the degree of safety necessary for primary safety; it is too easy to inadvertently avoid them in normal use.” For further information, see section 7 of DHF TS 0131:2021 Part 1: On-site guide. Nick’s sixth deadly sin is an excessive crushing force at a hinged gate’s lower edges. A lot of focus is rightly placed on main closing edge safety, but this is the area where a hinged gate exerts the least force when closing. “The much wider swept arc described by the lower edges during opening and closing will exert much higher force”, explains Nick. “The gate will generate dramatically increasing levels of force along the lower edges towards the hinge; body parts can more easily be injured in these areas as the gate opens or closes.” “The limits on an acceptable force are straightforward”, explains Nick. “Where body parts can be crushed, it is 400N or, where there is no crush potential, but a person may be impacted, it is 1400N. According to EN 12453, areas, where a body part could be crushed, must be assessed against the safety distances specified in the machine guarding standard EN 349.” Nick continues: “Feet and ankles are at greatest risk but the effect of the moving gate on hands, arms and other body parts of a fallen person must also be protected. Where there is a constant gap of up to 8mm or 120mm or more, the hazard is classed as impact only, but where the gap is between 8mm and 120mm, or where the gap changes due to slopes or kerbs etc during movement, there is a crush potential. For the vast majority of gates, there is a crush hazard along the lower edges and hence the maximum allowable force is usually 400N. “Safe edges are ideal for protection because they rely on the overtravel of the gate (stopping distance) being less than the compression available in the safe edge to achieve safe results. As the hinged gate overtravel reduces towards the hinge, any safe edge that can produce a safe force at the main closing edge end will also provide safe force at the hinge end. Inherent force limitation provided by sensitive drive units has the inverse effect, however; it is very sensitive at the main edge end of a hinged gate, but sensitivity reduces dramatically towards the hinge end. So, if there are crush hazards under the gate towards the hinge end, safe edges will be required on the lower edges to achieve the required safe force in these hazard areas.” For further information, see section 4.3 of DHF TS 0131:2021 Part 1: On-site guide. The final deadly sin is an uncontrolled closing force on traffic barriers. As traffic barriers are covered by EN 12453, the same safety rules apply. Despite rising arm barriers being primarily intended to control traffic, the previously mentioned machinery safety law requirement to cater for normal use and foreseeable misuse, all traffic barriers must also be safe for people. Nick explains: “Too many traffic barriers do not have the required protection on their closing edges. Many rely on magnetic vehicle detectors (useless for people) or rely solely on beams intended to supplement force limitation (see sin # 5) but without the required force limitation.” For further information, see section 6 of DHF TS 0131:2021 Part 1: On-site guide. Nick concludes: “As a federation, dhf is totally committed to raising standards, educating the public and increasing awareness across the industry. There is no place in our sector for illegal products and unsafe installations. Thankfully, the message is continuing to get out there as a result of our comprehensive training programmes, technical specifications, and collaborative working.” Door & Hardware Federation 01827 52337 www.dhfonline.org.uk Graph representing maximum force and time Examples of reducing gaps under hinged gates
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