1. In case of power failure, the sample is still placed in the oven, and can be dried to constant weight after returning to normal. When the vibrating screen fails due to power failure, a manual screen can be used to replace the vibrating screen.

2, put 300 grams of sand into the volumetric flask, don't weigh immediately, should shake the volumetric flask, eliminate bubbles.

3, pay attention to all 300 grams of sand into the volumetric flask, don't throw or have surplus.