9 Va. Admin. Code § 5-45-710
F. The composite vapor pressure of organic compounds in cleaning materials shall be determined by quantifying the amount of each compound in the blend using ASTM "Standard Practice for Packed Column Gas Chromatography" for organics and ASTM "Standard Test Method for Water Content of Coatings by Direct Injection Into a Gas Chromatograph" for water content (see 9VAC5-20-21), as applicable, and the following equation:

where:
Ppc = VOC composite partial pressure at 20ºC, in mm Hg.
Wi = Weight of the "i"th VOC compound, in grams, as determined by ASTM "Standard Practice for Packed Column Gas Chromatography" (see 9VAC5-20-21).
Ww = Weight of water, in grams as determined by ASTM "Standard Test Method for Water Content of Coatings by Direct Injection Into a Gas Chromatograph" (see 9VAC5-20-21).
We = Weight of the "i"th exempt compound, in grams, as determined by ASTM "Standard Practice for Packed Column Gas Chromatography" (see 9VAC5-20-21).
Mwi = Molecular weight of the "i"th VOC compound, in grams per g-mole, as given in chemical reference literature.
Mww = Molecular weight of water, 18 grams per g-mole.
Mwe = Molecular weight of the "i"th exempt compound, in grams per g-mole, as given in chemical reference literature.
Vpi = Vapor pressure of the "i"th VOC compound at 20ºC, in mm Hg, as determined by subsection G of this section.
H. If air pollution control equipment is used to meet the requirements of 9VAC5-45-650, the owner or operator shall make the following determinations:
J. For adhesives that do not contain reactive diluents, the VOC content of adhesive in grams per liter, less water and exempt compounds, shall be calculated according to the following equation:

where:
VOC = VOC content of adhesive, in grams per liter.
Ws = weight of volatile compounds, in grams.
Ww = weight of water, in grams.
We = weight of exempt compounds, in grams.
Vm = volume of material, in liters.
Vw = volume of water, in liters.
Ve = volume of exempt compounds, in liters.
K. For adhesives that contain reactive diluents, the VOC content of the adhesive is determined after curing. The VOC content of adhesive in grams per liter, less water and exempt compounds, shall be calculated according to the following equation:

where:
VOC = VOC content of adhesive, in grams per liter.
Wrs = weight of volatile compounds not consumed during curing, in grams.
Wrw = weight of water not consumed during curing, in grams.
Wre = weight of exempt compounds not consumed during curing, in grams.
Vrm = volume of material not consumed during curing, in liters.
Vrw = volume of water not consumed during curing, in liters.
Vre = volume of exempt compounds not consumed during curing, in liters.
L. The VOC content of materials, in grams per liter, shall be calculated according to the following equation:

where:
VOC = VOC content of materials, in grams per liter.
Ws = weight of volatile compounds, in grams.
Ww = weight of water, in grams.
We = weight of exempt compounds, in grams.
Vm = volume of material, in liters.
M. Percent VOC by weight shall be calculated according to the following equation:

where:
Wv = weight of VOC in grams.
W = weight of material in grams.
§ 10.1-1308 of the Code of Virginia.
Derived from Virginia Register Volume 26, Issue 12, eff. March 17, 2010.