BS EN ISO 13857:2008 free download.Safety of machinery — Safety distances to prevent hazard zones being reached by upper and lower limbs.
This document is a type B standard as stated in ISO 12100-1.
The provisions of this document can be supplemented or modified by a type C standard.
For machines which are covered by the scope of a type C standard and which have been designed and built according to the provisions of that standard, the provisions of that type C standard take precedence over the provisions of this type B standard.
One method of eliminating or reducing risks caused by machinery is to make use of safety distances preventing hazard zones from being reached by the upper and lower limbs.
ISO 13857:2007 establishes values for safety distances in both industrial and non-industrial environments to prevent machinery hazard zones being reached. The safety distances are appropriate for protective structures. It also gives information about distances to impede free access by the lower limbs.
4 Safety distances to prevent access by upper and lower limbs
4.1 General
4.1.1 Assumptions
The safety distances in this International Standard have been derived by making the following assumptions:
the protective structures and any openings in them retain their shape and position;
safety distances are measured from the surface restricting the body or the relevant part of the body; persons may force parts of the body over protective structures or through openings in an attempt to reach the hazard zone;
the reference plane is a level at which persons would normally stand, but is not necessarily the floor (e.g. a working platform could be the reference plane);
— there is some contact with the reference plane while wearing shoes (use of high-soled shoes, climbing and jumping are not included);
4.1.2 Risk assessment
Before determining the safety distance that prevents people from reaching hazard zones it is necessary to decide whether to use values for high or low risk. Thus a risk assessment (see ISO 12100-1 and ISO 14121-1) shall be conducted. The risk assessment shall be based on the probability of occurrence of an injury and the foreseeable severity of that injury. An analysis of the technical and human elements on which the risk assessment is dependent is essential to achieving the appropriate selection of data from this International Standard. The risk assessment shall take into account all accesses. Where several tables are used, the most restricting values shall be taken (see examples in Annex A).
NOTE 1 Aspects of frequency, duration, energy, speed and shape of contact surface need to be taken into account when establishing the risk of injury (see ISO 14121-1).
Where there is a low risk, at least the values in Table 1 shall be used (see 4.2.2.1.1). Where the risk is not low, Table 2, the high risk table, shall be used (see 4.2.2.1.2).