Standards for guards and protective devices

In accordance with the Machinery Directive, guards/protective devices must be provided when hazards associated with machinery cannot be minimised sufficiently or excluded all together.
 

A guard/protective device can be defined as a safeguard positioned between the danger zone and the user. A rough distinction is made between guards and protective devices.
 

A guard is part of a machine that guarantees protection by means of a physical barrier. The guard may consist of a casing, cover, gate, enclosure or similar.
 

A distinction is then made between the type of guard, whether fixed or movable.

• Standards for fixed guards
• Standards for movable guards

 

In contrast, protective devices do not present a physical barrier to prevent direct access to the danger zone.

• Standards for protective devices

 

Adjustable guards are used when access to the danger zones cannot be completely prohibited. This is the case on the bit for a drilling machine or on a circular saw blade, for example.

• Standards for adjustable guards restricting access

 

The effectiveness of particular types of guards and protective devices depends in part on the correct positioning of the relevant parts in relation to the danger zone. When deciding on these positions, a number of aspects need to be taken into account, such as:

• Type of devices to be used;
• Response times of the protective devices used;
• Time it takes to guarantee that the machine has reached a safe condition after the protective device has been operated, e.g. machine stopping time;
• Bio-mechanical and anthropometric data of parts of the body;
• Path taken by a body part when moving from the sensing or actuating element towards the danger zone;
• The possible presence of a person between the device and the danger zone;
• The possibility of undetected access to the danger zone.

 

The manufacturer must select a protective device appropriate for the hazard (sensing devices, two-hand circuits etc.). Naturally, the protective device that's selected must neither increase the hazard nor make working impossible. All this must be assessed in full when selecting the device.
 

The manufacturer must ensure that protective devices or equipment cannot cause additional hazards (e.g. by blocking the machine, which could prompt operating staff to remove the block under hazardous conditions, etc.).
 

It's in the manufacturer's interests, therefore, to provide precise justification for any decision not to equip moving parts with protective devices.