涼子迷

mesh是指單位面積中有的孔數~我看到都是正數
今天有人問我什麼怎麼會有負數的~

例如-200mesh

這到底是什麼意思阿?????
mesh數越大不就代表孔目越小~
那負數是什麼意思?????

希望知道的大大幫我解答一下喔~
多謝了~

shengweb

會不會是200-mesh才對......

涼子迷

我不是很清楚耶~他只告訴我負的~
這是什麼意思阿?請賜教了~

dddd

http://en.wikipedia.org/wiki/Mesh_(scale)

Particle size distribution
Powders and granular materials are sometimes described as having a certain mesh size (e.g. 30 mesh sand). By itself, this type of description is somewhat ambiguous. More precise specifications will indicate that a material will pass through some specific mesh (that is, have a maximum size; larger pieces won't fit through this mesh) but will be retained by some specific tighter mesh (that is, a minimum size; pieces smaller than this will have passed through the mesh). This type of description establishes a range of particle sizes.

One notation for indicating particle size distribution using mesh size is to use + and - designations. A "+" before the sieve mesh indicates the particles are retained by the sieve, while a "-" before the sieve mesh indicates the particles pass through the sieve. This means that typically 90% or more of the particles will have mesh sizes between the two values.

For instance, if the particle size of a material is described as -80/+170 (or could also be written -80 +170), then 90% or more of the material will pass through an 80 mesh sieve and be retained by a 170 mesh sieve. Using the conversion chart below, the resulting particles will have a range of diameters between 0.089 and 0.178 mm (89 and 178 micrometers).

anotherlevel

連重點都幫忙畫出來了

謝謝校長啊

taten

200目=75um

這個是篩網篩孔的網目數，
數字越大，代表粒徑越小

2目=8000um
10目=1700um
100目=150um
300目=48um
1000目=13um
10000目=1.3um

感謝dddd大的資料提供，"-"代表通過篩網。

atie

阿逗仔字　偶都看不懂

偶還真速厲害啊