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ing a law or regulation that cannot be reasonably enforced, and the ability to conduct verificational analyses by officials is an essential requisite. Some relatively complex approaches have been suggested for determining the density of BOV formulas that contain small amounts of propellant or volatile solvent (from the density and the delivered weight the deliverable volume can be calculated). One would be to extrude or spray some portion of the BOV content into a slightly pressurized—15 psi-g (1.0 bar)—pre-weighed, pressure-resistant glass tube. After reweighing and marking the meniscus the tube would be emptied, rinsed and then filled to the same level with water. This would give weight and volume figures, and thus the density. The reason for pressurizing the glass tube is to prevent foaming of gel-type products. Tube pressurization would not be needed for products that only contained volatile solvents, but the tube would have to be sealed to prevent evaporation. While this and other methods might seem enticing, they have major detractions. Air bubbles and meniscal obscuration have been mentioned. The manipulation of glass tubes, even under low pressures, could pose unacceptable hazards to officials, and lastly, the time needed to make just one net volume check would seem exorbitant. Marketing Aspects The primary marketing incentive for converting some BOV aerosols from net weight to net volume (contents) labeling has been to transpose them into the same net volume declaration used by similar, non-aerosol products. These other products would often be directly competitive. If the BOVs were to be labeled volumetrically (net content), then the consumer would have a level playing field for selecting the one with the greatest presumed value. As a subsidiary issue, the delivered (weight) contents requirement for aerosols, imposed by the states, might vanish if BOVs could be re-classified as “non-aerosols” and labeled by volume. An element that does not seem to have been considered is that plastic, glass and aluminum dispensers of lotions and other non-aerosols are almost invariably filled to about 97% of container capacity. In contrast, BOVs are typically filled to only about 60% to 70% of the can volume. There are technical rationales for this, such as the avoidance of excessive initial pressures, avoidance of jetting, and so forth. If we consider a 65 volume-% fill, for example, the BOV dispenser would have to be roughly 50% more capacious than a kindred non-aerosol in order to hold the same net content. It might be disconcerting to some consumers that the much larger dispenser felt to be about the same weight as the smaller non-aerosol forms of the same type product. Conversely, if the BOV dispenser was manufactured to be the same size as competitive non-aerosols, filled cans would only weigh about 70% as much. In 1978, and for years afterward, buyers had this type of problem with anti-perspirants. The U.S.EPA/ FDA fiat banning aerosol uses of CFCs caused marketers to change their formulas from about 80% CFC- 11/12 to ones that contained about 65% propane/ iso-butane propellants. The density of the products dropped from about 1.3 g/mL to about 0.7 g/mL. The typical can of CFC formulas held 4.0 oz., but with the hydrocarbon formulas the net weight had to be reduced to about 2.5 oz. No more than this amount of the much lower density formula could be safely fitted into the aerosol can. The unavoidable change quickly led to a tsunami of consumer complaints about under-filled or leaky dispensers, followed by a huge reduction in sales volume. On balance, the disparity between net weight and net content labeling of BOV dispensers does not influence the BOV “big can–small weight (or volume)” detraction. It exists about equally for both designations. Most products sold in BOV forms have densities in the 0.92 to 1.00 g/mL range. Taking 0.96 g/mL as an example, a net weight of 10 oz. would have a volume of 295 mL, which equates to 9.98 fluid ounces. This means that the numerical label declaration will be very similar, using either the weight or volumetric system, for nearly all BOV products. The advantage of using one form of labeling over another becomes questionable, except that the diligent consumer will be able to compare the BOV quantity declaration with non-aerosol counterparts having the same volumetric units of measurement. The purchasing advantage of this equivalency is moot. Water Bath Aspects Virtually all aerosols are currently required to be heated to at least their equilibrium pressure at 130°F (54.5°C) and this is done by passing them through hot water baths of various designs. The actual temperature rise of the product itself is no longer considered in the U.S. Dept. of Transportation (DOT) regulations. With the BOV products, which almost always contain nitrogen or compressed air (CAIR) in the exo-space, the absolute pressure increase in going from 70°F to 130°F is a mere 11%. Actually, the dispensers could be placed in boiling water without any physical damage to the can. If any BOV products are ever classified as “non-aerosols,” then the hot water bath test would not be applicable, at least not until the regulations might be revised. Actually, these pressure-temperature effects can be almost perfectly duplicated with certain non-BOV aerosols, if they contain nitrogen (nitrosols) or compressed air and where the product is essentially non-volatile. This would include lotions, cheese spreads (in piston cans), some polishes and so forth. The propellant is virtually insoluble in these products and (like BOVs) it simply acts as a piston to expel the contents. Consequently, the pressure increase during hot water bathing again relates to Charles Law and would be about as indicated for the BOVs. As with the BOVs the products themselves would be warmed only slightly. In summary, the technical data indicates that BOVs are not unique, but different from certain aerosols when it comes to pressure testing. For more information on this issue, see Regulatory Issues, beginning on p. 8. SPRAY Two sun care products in the same range, launched the same year, are labeled differently: “Fluid Ounces” (Coppertone Sport, above) and “Net Weight” (Coppertone Water Babies, below). Herbal Armor Natural Insect Repellent is a BOV labeled in fluid ounces. Weight vs Volume, continued 22 Spray April 2013


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