ISO 1973-2021 pdf download.Textile fibres – Determination of linear density – Gravimetric method and vibroscope method.
4 Principle
4.1 General
U ini’(hoil for detur tilining linear density are described
4.2 Gravimetric method, for bundles of (lb res
Specimens of a given length are weighed on a balance. This method is applicable to bundles of Iibres
4.3 Vlbroscope method. for Individual flbres
individual fibres of a given length and under specified tensioning force are subjected to vibration at resonance frequency. The linear density is determined from the conditions of the resonance state. i.e. the resonance frequency, the vibrating length 0$ the fibre and the tensioning force. The linear density Is read directly on the scale or a display of the vibroscope apparatus respectively reported by a connected computer system, This method assumes that the linear density of the tested length of the fibre Is constant.
Under certain cIrcumstances (e.g. a short vibrating length, a low tensioning force. high-modulus fibres) the vibroscope method results are falsified by 11w bending stillness of the Fibre, As a compensating countermeasure, a correction factor can be applied (refer to 8.2.1). ii agreed on by the interested parties.
S Apparatus
5.1 Gravimetric method apparatus
5.1.1 Balance. suitable for weighing the bundles of fibres to an accuracy of at least ± 1 %.
5.1.2 Device for cutting, the bundles under tension to a lt,ngth known within an accuracy of ±1 %and allowing an adjutiiient of the tension of the bundles to be cut.
For example, two razor blades set parallel in a suitable holder may be used
5.1.3 Comb sorter, for preliminary alignment of fibres.
5.1.4 Textile support fabric. ola colour contrasting with that of the fibres to be tested.
5.1.5 C.ljs plate. mea%ui-Ing approxImately 200mm • 200 mm. with one polished edge.
5.2 Vlbroscope method apparatus
5.2.1 Vlbroscope’). having the following accuracy
a) the applied tensioning force shall be within the range of ±0.5% of the specihed value;
b) the error in the vibroscope reading of resonance frequency mea’ciired or applied shall not exceed ±0,5 %:
c) the error in the vibroscope reading of vibration length of the fibre shall not exceed ti %.ISO 1973 pdf download.