Alkali Dosing Profiles and Mass Transfer in Jet Dyeing
Controlled progressive alkali dosing matches jet fabric loop velocity to eliminate surface fixation spikes and secure level shade fixation on cellulosic cloth.
Liquor Turnover Frequency
Circulation Metric
The rate at which the entire volume of processing liquid in a dyeing machine passes through the textile package or fabric rope is measured in cycles per minute. This liquor turnover frequency determines the consistency of chemical concentration and temperature across the entire load of textiles. High turnover rates are critical in ensuring that every portion of the textile interacts with the dye liquor under identical conditions.
Hydraulic Mechanism
In modern jet and package dyeing machines, a high-capacity pump continuously recirculates the dye bath through the fabric or yarn packages. The liquor turnover frequency is calculated by dividing the pump’s flow rate by the total volume of the liquor in the machine. Increasing this frequency reduces the contact time interval between successive exposures of the fabric to fresh dye solution.
This rapid replenishment ensures that any local depletion of dye or chemical additives is immediately corrected, promoting level dyeing across the fabric length.
Dyeing Performance
High turnover frequencies are particularly beneficial when using highly reactive dyes that fix rapidly to the fiber surface. In these rapid dyeing cycles, a high turnover rate prevents shade variation from the end to the start of the fabric rope. It also improves the efficiency of washing and rinsing steps by rapidly carrying away unfixed dye.
Operational Boundary
Process limits are imposed by the physical strength of the textile and the risk of yarn distortion or fabric pilling. Excessive liquor velocity generated by very high pump speeds can cause structural damage to delicate fabrics or dislodge yarns in package dyeing. The frequency must therefore be optimized according to the density and sensitivity of the textile substrate.