Operational Loads on Furniture During Their Usage

Studying furniture in validation stations is to simulate the forces causing damage to the furniture piece or its components, the loss of balance or deterioration of durability and safety, which may occur during normal use and during improper use, which can be expected with great probability. Before commencing any type of study, the furniture piece must be appropriately seasoned, ensuring it with complete strength.

By studying the components of furniture for storage, the capacity of extended elements is assumed as the product of the surfaces of the bottom of the extended element and the height of the span. All parts intended for storage should be loaded equally, in accordance with the values provided in Table 7.1, unless the design of the manufacturer says otherwise.

Drawers and other moving elements should be extended up to the blocking stops. If the element is not equipped with opening stops and is intended to be removable, then it is opened until the point in which one-third of the internal length remains inside the furniture piece. Then, a vertical force of 250 N must be applied, equal to the total mass of the extended element, in accordance with the scheme provided in Fig. 7.1.

Table 7.1 Load of part for storage

Door with a vertical rotational axis should be loaded by a force of 300 N placed at a distance of 100 mm from their outer edge. Then, the door needs to be moved, performing 10 full cycles from the position of 45° to the position of 10°, measured from the position of a complete opening, but to a maximum of 135° (Fig. 7.2a). Loading the door with horizontal force takes place using a load with a value of 80 N applied perpendicular to the plane of the door on its horizontal central line, 100 mm from the outer edge, in the direction of opening (Fig. 7.2b).

The durability of a hinged door and revolving door is tested by loading the edges with vertical force with a value of 20 N on the central line (Fig. 7.3). The quality of

suspension is assessed by examining the appearance and functioning of an unloaded door after the applied force subsides.

Testing the durability of sliding doors and horizontal louvered fronts consists in performing 40,000 cycles of opening and closing the door, and in the case of louvered doors, 20,000 cycles (Fig. 7.4). Before and after the test, the appearance and functioning of sliding doors or louvered fronts should be checked, and if necessary, also the force of opening and closing.

Sliding doors are also tested in terms of resistance to dynamic closing and opening, by suspending on a block a force with a value of 40 N, along with mass W (Fig. 7.5).

A component element of a furniture piece that causes many problems to con­structors is the flap of a bar, buffet or dresser. Therefore, in validation stations of furniture, there are tests that are to assess the durability of this element. For this purpose, at flaps that are positioned in full opening/closing, a static force with a value of 250 N must be applied (Fig. 7.6). Before commencing tests and after their completion, the appearance and functioning of the flaps, hinges, etc., need to be checked and then adjusted again, paying attention to whether the friction strut will allow the flap to open only under its own weight.

Within the framework of general safety requirements of office furniture, it is recommended that the edges and corners were without burrs and rounded or chamfered, not to leave open ends of tubes, all the moving parts, available during normal use, should be—during movement in any position—at a safe distance

<8 mm or >25 mm. This applies to any two elements moving relative to each other, with the exception of doors (including the hinges), flaps (including the hinges) and extended elements (including the runners). Safe distances should be maintained also between handles and other parts. Adjustable parts need to be constructed in such a way, as to prevent unintended operation or release. No louvered doors sliding vertically should close on their own from a height of more than 200 mm from the

closed position, as this may cause injury. Extended elements should have effective opening stops, which endure pulling out the case with a horizontal force of at least 200 N, exerted on the handle of the loaded pulled out element.

Safety tests provided in Table 7.2 must be carried out in accordance with PN-EN 14073-3:2006 and PN-EN 14074:2006. However, it is accepted that safety tests according to EN 14073-3 and EN 14074 constitute a part of a series of tests, when all essential tests are carried out according to EN 14073-3 and EN 14074.

For furniture hanging on a partition or wall, the order of their tests has been listed in Table 7.3.

Movable furniture should be tested in accordance with PN-EN 14074:2006. If the manufacturer did not establish otherwise, all parts of the furniture intended for storage, according to Table 7.1, must be subjected to load. Close the extended elements, flaps, louvered fronts and doors and apply a static horizontal force of 350 N at point A (Fig. 7.7), located on the vertical central line of the furniture’s construction, 50 mm below the highest point of this line, but not higher than at a distance of 1600 mm from the floor. If the furniture piece has a tendency to fall in one direction, then the point of applying force is lowered to a height at which tilting only in that direction is prevented.

An important test, from the operational point of view, is the assessment of strengths of shelf supports. If the shelves and their supports are identical, it is enough to examine only one shelf. If the shelves and their supports are not identical, then each combination thereof needs to be examined. During the test, the weight should be evenly distributed on the shelf, outside the section—with a length of about 220 mm, counting from one support—on which a blow bar should be knocked over 10 times at a point that lies as close as possible to this support (Fig. 7.8).

Table 7.2 The order of tests of furniture standing on the floor—free-standing or mounted to the building

Test no.

Test

Reference

1

Removing shelves

PN-EN 14073-3:2006

2

Strength of shelf supports

PN-EN 14073-3:2006

3

Strength of the top surface

PN-EN 14073-3:2006

4

Strength of extended elements

PN-EN 14074:2006

5

Dynamic opening of extended elements

PN-EN 14074:2006

6

Examination of stops blocking the opening

PN-EN 14074:2006

7

Vertical load on revolving doors

PN-EN 14074:2006

8

Dynamic closing/opening of sliding doors and horizontal louvered fronts

PN-EN 14074:2006

9

Strength of flaps

PN-EN 14074:2006

10

Furniture standing on the floor mounted to the wall of the building

PN-EN 14073-3:2006

11

Stabilitya

PN-EN 14073-3:2006

aIn the case of furniture which might not meet stability requirements, appropriate stability tests can be performed before commencing a sequence of tests listed in the table

Test no.

Test

Reference

1

Detachment of furniture mounted on a partition or wall

PN-EN 14073-3:2006

2

Removing shelves

PN-EN 14073-3:2006

3

Strength of shelf supports

PN-EN 14073-3:2006

4

Strength of the top surface

PN-EN 14073-3:2006

5

Strength of extended elements

PN-EN 14074:2006

6

Dynamic opening of extended elements

PN-EN 14074:2006

7

Examining the opening stop

PN-EN 14074:2006

8

Vertical load on revolving doors

PN-EN 14074:2006

9

Dynamic closing/opening of sliding doors and horizontal louvered fronts

PN-EN 14074:2006

10

Strength of flaps

PN-EN 14074:2006

11

Strength of partition and mounting elements

PN-EN 14073-3:2006

Fig. 7.7 Scheme of testing the strength of a furniture piece (mm)