How to measure correct LOI of Hot meal Sample,precisely saying Hot Meal is highly Hydroscopic material

1.After Taking sample from sampler Point it has to be kept in desicator for cooling then weigh or by kept in oven for 10 min then in disicator & then weigh it.What is correct step for it.

2.If Kiln is disturbed for dustyness from Quality point of view what we have to check like Raw Mix , Coal Ash,Precalciner Temp is correct or not i.e Hot meal DOC

3.How to measure effiiciency of PreHeater