BS EN ISO 12951-2015 pdf download.Textile floor coverings 一 Determination of mass loss, fibre bind and stair nosing appearance change using the Lisson Tretrad machine.
5.12 lIed plait
The bed plate faces are parallel to tIre track travelled by the Tretrad feet and the (rant edge of the plate is rounded with a 10mm radius to simuLate a stair nosing.
The test surface is formed by the width of the Tretrad feet and the length of the track over which the tretrad runs. The track length shall be determined (or each machine by measunng the distance between the front edge of the base plate arid the perpendicular projection of the Ttetrad axis at its furthermost point of reversal. The length oltrack shall be (800 *20) mm.
Two clamps mounted ateach end ot the bed plate are used to hold each specimen under tension. The tensrnn is applied by means of a weighted third clamp, each specimen being subiected to a force of (20*2) kg.
5.1.3 Tre’trad assemblies
The Lisson Tretrad apparatus has two Tretrad assemblies, each of which comprises a Tretrad mounted In a frame that Is free to rotate around an axis that is 135 mm to 140mm above the upper surface of the bed plate.
Each TI-etrad comprises four equally-spaced legs with rigidly attached feet platforms.
The surface of the foot platform has a radius of curvature 01(112.5 a 1) mm. a circumferential length of (100,0 * 1,0) mm, and a width of (55.0 *0.5) mm. The ends of the contact surfaces of the platforms are rounded with a radius of (4.0±0.5) mm
The vertical force applied by the Tretrad feet. in the stationary state, shall be (15,0 a 2.0) kg measured without the soles in position (see FIgure 2).
The linear speed of the ‘rretrad is (0.28 * 0.02) rn/s and the peripheral speed of the Tretrad with sole coverings Is (20.0 t 2.0) % greater than the linear speed. This causes slippage of the feet on the test spec mien in addition to the compressive action,
At the front edge cr1 the bed plate, the Tretrad runs beyond the bed and is held horizontally by a height admustable stopper, in such a way that the lower edge of the foot (without sole material) can be adfusted between 5mm below and S mm above the level of the surlace of the bed ilace (see F,gwe2)
At the points of reversal, the Tretrad remaIns stationary for approximately I g during this stoppage at the forward point of reversal, the Ttetrad is rotated through an angle (but not a right angle) to ensure that the feet walk evenly over the length of the test area.
5.1.4 Vacuum cleaning system
Suction nozzles follow the horizontal movement of the Ttetrad assemblies, The nozzles are flexibly mounted and are equipped on their undersides with slides that rest on the edges of the test specimens. thereby not linposuig any wear on the specimens.
Each nozzle has the dimensinns shown in Figurel and is connected to the vacuum cleaner to extract the abraded fibre.BS EN ISO 12951 pdf download.