Textile Dyeing
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WEKA Standard Series 20: Textile Dyeing Machines Typical application conditions Media Pressure 140°C, max. Density 1.0 (approx.) Type Application Several types of machines are used for the dyeing of textile material. This can be fabric in the form of long pieces or rolls, or thread and yarn in reels held in containers. In some types of dyeing machines, the material is submerged in dye liquor and then subjected to cycles of temperature and pressure ranging from vacuum to high pressure. Vacuum is used to fully remove air embedded in the material, while high pressure is used to ensure full penetration of the dye into the material. The way a dyeing machine functions, the number of cycles in a process batch, temperatures, pressures, etc. depends on the textile material and the technology of the machine manufacturer. 5 bar G, max. Temperature VLI Type 23614-K Dye liquor Type 23614-K Special Traditional instrumentation and associated problems Dye liquor absorption varies for different textile materials and for different process conditions. Therefore the quantity of water required for each process batch cannot be pre-calculated: it must be determined by controlling the level of dye liquor in the machine. Sight-glass type level gauges have been in the past for this application, along with various types of level detection devices (e.g., conductivity and magnetic float type level switches). A major disadvantage of sight-glass level indicators is that the dye gets deposited on the inside of the tube, so that in a relatively short time it becomes difficult or impossible to observe the level. Mechanical level detectors such as the magnetic float switch type do not work too well in this application because frequently occurring loose fibre builds up on the float arm, restricting its movement or jamming it. Conductivity type level switches are also affected by material deposited on the sensing electrodes. Conductivity type level switches are further affected by changes in conductivity of the dye liquor due to different types and concentrations of dyes and additives, and also due to temperature changes. WEKA advantages WEKA VLI Level Indicators always give a clear display of level irrespective of process condi- WEKA AG · Schürlistrasse 8 · CH-8344 Bäretswil · Phone ++41 (0)43 833 43 43 · Fax ++41 (0)43 833 43 29 · www.weka-ag.ch

tions because the indicator assembly is totally isolated from the media. For this application, the magnetic float is electro-polished to increase its immunity to deposits forming on its surface and to corrosion by the dye liquor. The top and bottom ends of the float chamber have threaded plugs for easy servicing and cleaning, whenever the need arises. The level detecting magnetic switches are also totally isolated from the media, and have a very long operating life expectancy. WEKA AG · Schürlistrasse 8 · CH-8344 Bäretswil · Phone ++41 (0)43 833 43 43 · Fax ++41 (0)43 833 43 29 ·...