Determining trash content in cotton

Shirley trash analyzer is used
100 g cotton sample is processed & fibrous portion collected in ‘trash tray’ is processed again through trash analyzer
Collected trash (after second passage) is weighed & expressed as % of weight of cotton
It is trash % of cotton & invisible loss is ignored
Non-lint content = 100- lint% is not used (as it includes invisible loss)

Obtained trash content gives good correlation with B/R droppings, & can be used to predict process waste in B/R

If cotton consists of seeds...

Test 100g fresh sample (without seed) for trash %
Estimate % of seed weight by manually separating

seeds from 1 kg of cotton
This weight % of seeds should be added to trash % of

cotton to obtain total trash content

E.g. Trash content in cotton is 5.5% and weight of seeds is 20 g in 1 kg, then total trash content is,

Total trash content = 5.5 + (20 × 100)%1000 = 7.5%

➢Due to use of hybrid cottons, proportion of seed coats has increased

➢These seed coats have fibres attached to it, and are difficult to remove

➢Causes thick places, neps, & short length slub-like faults in yarn

➢Therefore, % of seed coat type trash in mixing must be determined

➢Can be measured by sieving trash obtained in above procedure through a mesh-10

➢Matter that remains above is called as seed coats

Cleaning Efficiency

Trash content of cotton fed to machine & cotton delivered from it can be used to calculate cleaning efficiency
Cleaning efficiency of machine = [Trash in feed(%)- Trash in Delivery(%)]/Trash in feed(%) * 100
Cleaning efficiency of sequence of machines is not equal to sum total of cleaning efficiencies of individual machines in sequence