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FAQ with the Axelent Safety Group

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Machine safety is not always easy. That is why we have collected our most frequently asked questions that we receive from our customers. If you do not see your question below - send us an email in the form below and we will answer as soon as possible!

FAQ - general and simple



What is the minimum height of safety fences?

1400 mm, because then it is not possible to just jump across. 1000 mm is allowed, but only if there are additional safety measures (e. g. detection of person entering the hazard area by means of a light curtain or laser scanner), see EN ISO 13857.


What is the maximum gap allowed between the floor and the bottom edge of safety fences?

180 mm is given in EN ISO 13857. However, EN ISO 11161 for integrated manufacturing system allows 200 mm. It is safer to go for 180 mm or less (X-Guard standard 100 mm) to prevent persons from accidentally sliding into a hazard zone underneath a fence.


When do parts of a fence need so-called no-loss fasteners?

A no-loss fastener remains connected to either the panel removed or the post. No-loss fasteners are mandatory when the guard element must be removed for planned work, such as regular maintenance (EN ISO 14120). In such cases fasteners are removed routinely and could thus be lost. Axelent X-Guard features quick-release fasteners that require a tool to be used to open them (the X-Key). However, all parts of the quick-release fastener remain firmly connected to the fence parts.

When will a door in a safety fence need a monitoring switch?

Consider two questions, when deciding this (based on EN ISO 14120 section 6.4.4):

  • Why would people go in? If the reason for access is a standard operating procedure or remedy of frequent errors, then the door must be monitored. If the reason for access is maintenance, repair, or less frequent errors, then a monitoring switch will not be needed. However, if there is no switch, it must not be possible to open the door without using a tool or key.
  • How often will people go in? Even if access is only needed for maintenance, repair, or less frequent errors, but more than once a week, the door will need a monitoring switch.


Why is a safety distance between the inside of a fence and a hazard required?

A fence will prevent persons from entering the hazard zone. However, somebody could stick his fingers (accidentally or deliberately) through the openings in the fence. Fingers are about 120 mm long. Therefore, the minimum gap on the inside is 120 mm. If the mesh pitch allows a person to stick the index finger in together with the thumb, the distance will be 200 mm (compare EN ISO 13857).

Some door switches prevent the door from being opened (so-called “guard locking”). When are such switches needed?

When a door is opened during operation of the machine, it may take a while for the machine to stop completely. If that continued run or movement would allow persons to reach a hazardous moving part, the door needs to be locked. When guard locking switches are fitted, the operator will have to first “tell” the machine that he wants to enter (usually, he/she will press a button). Then the machine will stop and only then release the door lock. With this additional safety measure, people cannot reach moving parts after opening a door.

 

Is it required that access doors in safety fencing always open to the outside?

This is not required directly in generic safety standards or the Machinery Directive. However, EN 528 for rail dependent storage and retrieval equipment requires this. In building construction this also is a requirement; doors in escape routes must always open toward the safe area (generally that is the outside of a hazardous area or the outside of a building).

For machinery one should decide this as part of risk assessment. Consider the following:

  • Is it possible to walk into and inside the machine or system? If a person could stay inside the fenced-in area, he/she could be endangered in there.
  • Are there permanent hazards inside the fenced-in area or could a hazard come up while a person is inside? In many cases this cannot be completely excluded; even when machinery has been shut down, maintenance work may cause hazard, forcing a person to leave the fenced-in area quickly.
  • If the doors in a safety fence may thus be considered escape doors, they should open to the outside. And even more importantly: If the door is held closed by a guard lock that prevents opening, a so-called “escape release” must be fitted to allow opening the door from inside at any time.

But what to do, if there is no space to allow the door to open to the outside? Then there must be enough space inside the hazard zone to open the door safely and quickly toward the inside. Plan for an escape route width of at least 650 mm (better 800 to 1000 mm). If all of that is not possible for space constraints, you will need to install equipment allowing safe detection of persons inside the hazard zone. Such equipment must switch any hazard off when persons are detected inside (pressure-sensitive mats, laser scanners, etc.).


Must safety fencing be earthed or connected to the safety bonding circuit of the machinery?

Yes, in most cases that is required as of September 2021, since safety fences are considered “extraneous conductive parts” of the machinery (see EN 60204-1 section 8). Only if the fence is more than 2500 mm away from the power conducting parts inside the fenced area and if no electrical cables are laid on or along the fence, earthing may not be needed.

Q&A with the Safety Group

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