23rd October, 2015
by Ergonomics Department
This article examines BS EN 1335-1:2000 Dimensions, determination of dimensions. With the publication of the European standard, BS 5940 Part 1 will no longer be applicable to office work chairs which are height adjustable. Hence from now on, all office chairs have to comply with the dimensional requirements of BS EN 1335 Part 1.
The dimensions in BS EN1335-1 are similar to those in BS 5940-1:1980 (withdrawn)
However, the European standard has two new dimensional requirements for the star base; one is anti-stumbling and the other is the stability dimension. These should not cause any problems for chairs already on the market as they are likely to be within the specified dimensions. Unfortunately, this does not mean complying with the standard is all plain sailing.
As work on the standard has been going over a long period, it is already behind the state of the art office chairs. Methods of measuring dimensions are not new and have the same problems we encountered with BS 5940. Hence the measurement techniques are still complicated and sometimes do not simulate real use of office chairs
There is an even bigger problem than the measurement techniques. The table containing dimensional requirements is unnecessarily complicated and difficult to understand. The matter is made worse by including requirements for three types of chair without any descriptions or guidelines.
The problem is deciding which type of office work chair is being tested. The fact that there are three types also create confusion on the suitability of any of these chairs for use at display screen equipment (also referred to as VDU or computer) workstations.
There have already been rumours that only one type of chair specified in the standard will be acceptable for use at VDU workstations, which clearly is not the case. This European standard specifies three types of office chair but does not state which types of chair will comply with the European display screen equipment directive’.
As it is very difficult to give precise descriptions of each type of chair, this information annex will include broad descriptions of each type of chair and the main differences between them. These broad descriptions are summarised below.
The type A chair is essentially the same as the type B chair with the following additional requirements:
This is the most common office chair. Type B chairs can have independent backrest adjustments in relation to the seat surface, but it is not compulsory.
Dimensionally, they are the same as type A chairs except for the minimum seat height, which is 420mm and the minimum seat height adjustment range, which is 100mm.
The type C chairs are dimensionally similar to the type A chairs, but can have:
As can be seen from the guidelines above, Type A chairs have many more adjustments and must have adjustable seat depths and angles. Type B, are those most commonly used in UK offices. Both types are likely to comply with DSE regulations. Type C are the very large chairs with bulky upholstery and limited adjustability.
These chairs may or may not satisfy the minimum requirements of the DSE regulations.
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