Particle Mesh Size units

[simonsb]

Much soil sampling and geochemistry data uses particle mesh sieves to sort the sample and catagorises the fraction by the "mesh size" (see eg http://en.wikipedia.org/wiki/Mesh_(scale), http://www.azom.com/details.asp?ArticleID=1417. The UCUM standards at http://aurora.regenstrief.org/~ucum/ucum.html specify a "mesh" value "mesh lineic number [mesh_i][MESH_I][in_i]" but this does not appear to be related.

Is there an appropriate "mesh" unit available in UCUM?

[gschadow]

This is similar to Gauge scales. Please provide a conversion function and a proposal for a unit symbol, then we could add this. If it's just some ordinal scale, then it would not need a unit.

[simonsb]

Table showing various mesh sizes

[simonsb]

Replying to gschadow:

This is similar to Gauge scales. Please provide a conversion function and a proposal for a unit symbol, then we could add this. If it's just some ordinal scale, then it would not need a unit.

The only UCUM reference I can find is to gauge of catheters: Charrière, french gauge of catheters Ch [Ch] [CH] no 1 mm/[pi]

I understand from the attached table that the Mesh Size is a different unit of measure.

[SimonCox]

On further investigation, I believe that Lineic number is correct. It is defined as inverse length - i.e. number per unit length. I think all mesh numbers are a scaled inverse-length, so are a lineic number. It just requires the scale factor to be determined.

[gschadow]

Could be inverse length or inverse circumference or even more complicated. I have once tried to understand needle gauge numbers but had to give up because I could not find a clear definition. This will go into UCUM almost automatically as soon as someone can research a formula -- however complicated -- that relates these gauges or mesh sizes to a standard unit in some way.

[SimonCox]

Spreadsheet of seive openings mapped to various seive number designations (taken from the other attachment)

[SimonCox]

The attached spreadsheet shows that the seive designations are not a strict Unit of Measure, as the relationship between numbers and opening size cannot be expressed as a formula. The British scale is close - (British seive number) = 15300/opening(expressed in um)

but in general seive numbers are an ordered-nominal scale, nit a unit-of-measure.