By Montfort A. Johnsen, Ph.D. Technical Ed itor April 2015 Spray 25 While acetone is a non-VOC, its volatility and extreme flammability are of concern. Some contract fillers decline to use it in formulation work, citing personnel and plant safety reasons. The branched heptanes also have Tagliabue closed cup tester (TCC) flashpoints well below room temperature. Air Conditioner Refills There has always been some definitional controversy surrounding air conditioner (A/C) refill products, with some people claiming they are not aerosols, since they have no valves and do not produce sprays, foams, gels or other visible emissions. Instead, they all have valve cups with a threaded pedestal, designed to enable their connection to the low pressure inlet of A/C units to add HFC-134a coolant if needed. Since the HFC-134a (plus trapped air) pressure is always slightly over 200 psi-g. at 130°F (13.8 bars at 54.4°C) all of these products exceed the U.S. Dept. of Transportation (DOT) pressure limit of 180 psi-g. at 130°F (12.4 bars at 54.4°C) for DOT 2Q containers. Consequently, they must be marketed in containers designed to safely release any excess pressure—thus preventing any distortion or bursting. A special DOT permit is required, e.g., DOT E 10232, and this must be inscribed on the can label. Many of the cans now marketed are of two-piece tinplate or steel construction and their curls (beads) are not quite as smooth as those of the three-piece tinplate cans. Consequently, to ensure against possible leakage the valve cups are fitted with lathe-cut Buna-N gaskets with a typical thickness of about 0.040" (1mm). Many marketers offer HFC-134a A/C refill units. Interdynamics offers R-134a in an ITW Sexton A57 tinplate 300x315 (76x121mm) two-piece container filled to 12oz. The pressure relief vent operates at 380 psi-g. (26.2bars) minimum. Capacity is 405mL. The formulation contains a trace of fluorescent dye that glows under UV light to pinpoint the smallest leak in the A/C system. IDQ Holdings markets 134a Leak Sealer in the same can size and fill weight. The HFC-134a coolant contains a “system-safe” leak sealant that also protects against wear and extends system life. Lastly, it claims to increase A/C cooling. IDQ Holdings also markets the 134a+ Giant Size Ultra Synthetic NASA Arctic Freeze, using a 211-diameter DS Container of about 800mL capacity. The fill is 22oz. Label claims include the leak sealant, along with a promise to produce cold air up to 50% faster. Uniquely, the container is taped to a testing device that consists of an adapter, generous length of pressure-resistant plastic tubing and a 1.5” diameter pressure gauge. The face of the gauge divides the scale into green (normal), yellow (caution) and red (danger) sectors. Automotive Enamels A special area of the large aerosol paints and coatings category is separated out for automotive products. The Rust-Oleum Corp. offers several of these products under their “Custom Shop” labels. One is an enamel able to withstand “high heat to 2000°F" (1093°C). The 12oz. product is packaged in a 211x713 (65x198mm) tinplate can with small black overcap and a plastic finished paper label. A very similarly packaged product provides a matte finish that stops rusting. Still another is Caliper Paint that is satisfactory up to 900°F (482°C). It stops rust and is brake dust resistant. The 12oz. container carries a full diameter plastic cap with squeeze panels on opposite sides for easy removal by adults. Rust-Oleum also markets the 11oz. Engine Enamel in a 211x713 (65x198mm) tinplate can with stir pellet. It resists temperatures to 500°F (260°C) and is gasoline- and oil-resistant. The line is available in several colors. The firm’s Automotive Enamel is marketed in 12oz. (211x713) and 15oz. (211x908) packaging with the full diameter plastic squeeze cap. The Dupli-Color Products Co. markets its Shield automotive product line, which includes road…
Spray April 2015
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