The History of Furniture Construction

Requirements Concerning Safety of Use

Specific quality characteristics attributed to this group of furniture, which distin­guish them from other types, are conditioned by the nature of use and certain external factors, which in the practice of approval tests is called exposures and operational loads of the furniture. In considering the movable element, e. g. a drawer of an office container, we shall notice what requirements it must meet. These include the following: capacity adapted to the overall dimensions of the folder or binder, the presence of staples for documents or dividers, the amplitude of

extension much larger than the dimension of its depth, which is connected with the necessity of installing special types of runners with a large vertical load indicator and multiple extension range, an auto-lock system of the extension of other drawers in order to preserve the stability of the furniture piece and the installation of a handle with an internal lock. Among furniture of case construction of a significant height, with a large number of drawers, there could be a risk of the loss of stability after extending all the weight-bearing drawers, as a result of overload. Because such a danger must be absolutely excluded, especially in this group of furniture, the construction of cupboards and file cabinets should have a system of fittings that limit the user’s ability to open all of the drawers simultaneously. In turn, double-blind doors are mounted together with a special block system with a tie.

Modern office furniture has a very complex design and is equipped with elec­tromechanical devices that facilitate the use of the furniture and optimal use of office space. Mobility, that is a group of construction characteristics conducive to easy movement, is currently the key advantage of office furniture. Their different character is also shown by the modern architectural concept of the office’s interior. In accordance with this concept, the floor of office space consists of a so-called technical floor, between its layers the complete cabling of office equipment, having output sockets, is mounted. Then, office equipment, such as computers, telephones or lighting, is connected to appropriate sockets in the floor, through special chan­nels. Currently, a wide variety of cabling solutions can be encountered from the worktop of tables and desks to complex sockets in the floor. An interesting prop­osition in this regard is sleeves of a spinal construction. Such solutions are used also in work tables with regulated height. The system of hidden cabling ensures an aesthetic look of the office, because it eliminates the possibility of being caught up in loose cables. In addition to compliance with stiffness and strength standards, an office piece of furniture must also meet additional conditions related to use (Beszterda 2001; Dzi^gielewski and Smardzewski 1995; Smardzewski 2004b, c; Smardzewski and Beszterda 2001; Smardzewski and Rogozinski 2001a, b). The construction of this furniture with internal channels must be completely safe to use. For this reason, some elements of the furniture piece should be made from appropriate insulators, ensuring electrostatic not allowing for electrical arching within the structure of the elements.

The emerging new aspects of functionality of a furniture piece, and therefore, new structural solutions, must, regardless of the complexity of the structure, meet the standardised safety rules of use, strength and stiffness. The methods of calcu­lating stiffness, stability and strength of the construction of office furniture have been presented in the works of Dzi^gielewski and Smardzewski (1995), Smardzewski and Rogozinski (2001a, b). In Poland, mandatory requirements relating to the quality of office furniture are determined by the norms: PN-EN 1335-1:2004, PN-EN 1335-2:2009, PN-EN 1335-3:2009, PN-EN 527-3:2004 and PN-EN 16139:2013-07 according to them:

• stability under vertical load aims to demonstrate adequate resistance to the construction falling over due to people using its worktops,

• stability with extended drawers aims to demonstrate adequate resistance to the construction falling over with drawers of a maximum load and completely extended,

• a strength test of vertical force with a value of 1000 N aims to test the strength of the worktop and construction of a desk/table affected by occasional, short-lasting loads,

• the test of resistance to horizontal force with a value of 450 N aims to test the strength of the construction of a desk/table affected by forces exerted by the user when moving the furniture piece,

• testing fatigue as the result of horizontal force with a value from 0 to 300 N aims to test the strength of the construction of a desk/table affected by small forces exerted cyclically, as well as the opening and closing of drawers and cautious moving, in order to ensure that during use, the construction can endure moving without any apparent deformations of its worktop.

• testing fatigue as a result of vertical force with a value of 400 N aims to verify the strength of the construction of a desk/table affected by forces directed downwards,

• test of falling aims to test the ability of tables to counteract falling over,

• testing the stiffness of the construction aims to determine the stiffness indicator of the construction of a desk/table determining its resistance to unacceptable deformations of the frame caused by horizontal force with a value of 200 N.

In addition, safety requirements have been defined in the scope of

• the shape and dimensions of corners, edges, in order to avoid slamming, pinching, cutting, physical injury or damage to the things of the person using it,

• the shape and dimensions of movable and regulated parts, in order to be able to avoid injuries and unintentional launching,

• the quality of joints exposing to excessive damage or loosening,

• protection against contaminating the body or clothing of the user,

• stability during stresses on the front edge of the seat, tilting of the user to the sides, resting on backrest or sitting on the front edge of the seat,

• resistance to rolling an unladen chair,

• the strength and durability in order to avoid injury by the user of the chair: sitting both in the middle and outside the centre of the seat, while moving forward and to the sides when sitting, along with leaning over the armrests, at pressing on the armrests when standing up from the chair.

It is worth noting that by acceding to designing office furniture and office space, one should be aware that individual elements of the equipment of a workstation should provide the possibility of free and easy arrangement of office space, so that the office does not limit employees and the company in realising business tasks (Smardzewski and Rogozinski 2001a, b).