Particulates not otherwise classified

Mg(OH)2 powder is classified by OSHA as a nuisance dust. ACGIH categorizes the powder form as particulates not otherwise classified. Exposure limits are as follows (108) ACGIH 10 mg/m , OSHA 5 mg/m (respirable), and 15 mg/m (total). Magnesium hydroxide is reported in the EPA TSCA inventory (109). 

Nuisance particulates, see Particulates not otherwise classified (PNOC) Dusts... 

ACGIH Particulates not otherwise classified (PNOC). Documentation of TLVs and BEIs, 6th ed, p 1166-67. Cincinnati, OH, American Conference of Governmental Industrial Hygienists (ACGIH), 1991... 

EXPOSURE GUIDELINES ACGIH TLV 10 mg/m (total dust containing no asbestos and 1% crystalline silica for Particulates Not Otherwise Classified (PNOC)) OSH A PEL 15 mg/m (total dust), 5 mg/m (respirable fraction) NIOSH REL not established IDLH not determined. 

KEY REFERENCES 4 15 (note information concerning exposure guidelines for particulates not otherwise classified was obtained form the NIOSH Manual of Analytical Methods (NMAM), Fourth Edition). 

ACGIH. 1996. Particulates (insoluble) Not Otherwise Classified. In Documentation of the threshold limit values and biological exposure indices. Supplement. American Conference of Governmental Industrial Hygienists. Cinciimati, OH. 

The disperse phase is constituted by discrete elements. One of the main assumptions of our analysis is that the characteristic length scales of the elements are smaller than the characteristic length scale of the variation of properties of interest (i.e. chemical species concentration, temperature, continuous phase velocities). If this hypothesis holds, the particulate system can be described by a continuum or mean-field theory. Each element of the disperse phase is generally identified by a number of properties known as coordinates. Two elements are identical if they have identical values for their coordinates, otherwise elements are indistinguishable. Usually coordinates are classified as internal and external. External coordinates are spatial coordinates in fact, the position of the elements in physical space is not an internal property of the elements. Internal coordinates refer to more intimate properties of the elements such as their momenta (or velocities), their enthalpy... 

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