ISO 7174-1:1988 pdf download – Furniture – Chairs – Determination of stability Part 1: Upright chairs and stools.
7 Test procedures
7.1 Caperirnetitel ittethod — Chairs
7.1.1 Forwards overbalancing and sideways overbalancing for chairs without ants
Position the cha with stops agetnet the front legs and against the legs on one side lea appropriate). Apply a force of 000 N vertically by means of the loacing pad so as to act at a point 50 mm from the edge of the seat at those poediorn along its exposed periphery must likely to result ii lrtstdMllty lususy teats on the contr*te arc sufficient). Apply a force, F, as specified in the annex or at reqitiremsit itonirnants tinrizontaly along a horizontal site extended forward from the point wtiere the base of the loading pad meets the upper surface of the seat Ieee figure 11 Record whether the chair overturns and the force used.
Chairs with adiustable backrests, and reclining and tilting chairs shell be tested with their back assemblies locked or set an as tn be wicsiiotj roerwartis frorii the vertical by 15 ± 5°. Free swivceing backrests shall be loodod on thoir area of rotation newt when thkt axis is ret? ar%tmtahle tn the shove requirement
7-12 ltearwsrds overbalancIng
Position the chal with the stops against the rest legs, Apply e vertIcal torte of 6(1) N to the seat by nisans of the baling — di a point 175 mm forward of the centre of the line of intersection of the soot end beck surfaces. Determine the distance, A, hetween the loaded seat height and the floor by meesunng the distance between the horizontal bar and the base of the pad, end subtracting it from the dfltsnce between the horizontal bar and the floor.
Apply a force, F, ae specified in the annex or in requirement documents horizontally to the back of the chair at s height of 300 mm above the unloaded seat or at the top edge of the backrest, whichever is the lower Isee figure 21 Record whether the chair overturns and the force used.
Adpacsteble angle bectrests shall be set at the reermoet point of the working adustment range. Free swivelling bactrests shall be loaded on their asic of rotation.
7-1.3 Sldewsys overbelencing f or chaIrs wIth arms
Position the chair with stops agaeist the legs of one side. Apply a vertical (cite uf 250 N et a point 100 twit to over side of the fore and alt centreline of the seat and botwoon 175 tern and 250 mm forward of the ran edge of itt seat Apply a vertical torte uf 350 N by means of the loading ped ats point 37,5 tree irerido the outrs edge of the arm at the most adverse position along its tangtft Apply. horizontal force es specified in the annex or It requirement documents outward at the upper surface ol the arm rest and in tine with the vertical arm force on the side with restrained feet (see figure 31- Record whether the chair overturns and the force used.
7.2 ExperImental method — Stools: all dIrectIons
Poeition the stool so that two leet sre resting against the stops Apply a vertical force of 500 N by mean of the loading pad at a pomt 50 mm from the .dg. of the seat nereat th. stopped feet. Apply a horizontal force as specified It (he annex or In requirement documents through the centre of the seat in a direction tovards the Biopped feet i.e figure 4). Record whether the stool oyerturrw and the force used.
7.3 Calculative method — Chairs
7.3.1 Genetal
Ifl the calculative method, the seat loedng pad is not used. Instead, [he reajetanue tu uvurturr.n (hit wuld hive been caused by such boding is token into coneiderstion in the calculetinn, which is based tin the mnrnerits shout the re sifaIted feet. For this caictianon cmstances a. b and It are measured:
– dIstance a Is the minimum horizontal distance from the hne of the stopped feet to the vertical proiectlon of the point of application of th, seat load, W, had auch been applied:
— distance b as the horizontal distance from the stopped feet to the arm load point;
7.3.2 Forward, overbalancing and sideways
Poeition the chair firstly with the stop. against the front legs and then with the stop. against the bags on one aide. Apply a graduvily incsaesirig force. F, acting ID till th utter uvut the roatroinod legs horizontally at the intorsocton of the soot and hark w1arsis Racnrd th, value of F0 when the tinreerrainvid legs lift ott the flOOr, Measure distances and a.
Calculat, the force F required to overturn th, chair hid it been loaded with a seat load, It, of 600 N from the following formula.