The intrinsic water efficiency of a machine is measured by the liquor ratio. This is the ratio of water to thread once the machine is filled, and typical older machines will operate at a ratio of 8:1 while more modern machines, can operate at 4.5:1. This is a 44% saving in water for the same output, and is largely achieved by improved design of pumps and pipework. However, while all our new machines are low liquor ratio designs, with almost 2000 dyeing machines in use, we have a lot of older machines that still have years of life in them.
Our team in Bangladesh have been challenging themselves to find ways to achieve lower liquor ratios on old machines without modifying the machines themselves. Through a combination of maximising the thread load, optimising the water level, rationalising flow direction and adjusting the pump speeds they have managed to reduce the liquor ratio from 8:1 to 6.5:1, a 19% reduction in water used. The water saving also impacts on energy use as a lower water volume takes less heat energy to raise it to operating temperatures.
We will be spreading this innovative approach across other dyehouses in 2020.