Question

The CV % of mass irregularity of yarn generally equals U % multiplied by

• A. 1.00
• B. 1.25
• C. 1.44
• D. 1.82

Hint:

CV% is typically about 1.25 times U%. This is a standard approximation used in yarn testing.

Answer 1

The Correct Option is B

Step 1: Understanding Yarn Irregularity Measures: U% (Uster Percentage): A measure of yarn evenness, representing the mean deviation of the yarn's linear density. Lower U% means a more even yarn. CV% (Coefficient of Variation Percentage): Another measure of yarn evenness, representing the standard deviation of the yarn's linear density, expressed as a percentage of the mean linear density. Lower CV% means a more even yarn. 
Step 2: Relationship between U% and CV% The relationship between U% and CV% isn't perfectly linear, but for most practical purposes, especially for cotton yarns, the following approximation is widely used: \[ \text{CV\%} \approx 1.25 \times \text{U\%} \] This relationship arises because U% uses the mean deviation and the distribution of yarn mass is not perfectly normal, there will be this constant factor of 1.25.