Industry expects modified Rule 66 Los Angeles County's solvent emission rule in present form would raise costs for solvents users Last week, scientists working with an air irradiation analysis chamber in Los Angeles completed a series of tests that could have repercussions for paint makers and other solvent users from California to Maine. The tests, a cooperative effort of the California Manufacturers Association and the Los Angeles County Air Pollution Control District, are on vapor emissions from The results will organic solvents. help in preparing a modified version of Rule 66—APCD's highly controversial proposal to control the amount of organic solvents emitted into the air. Rule 66 was first aired in detail last November at a seminar sponsored jointly by CM A and APCD (C&EN, Nov. 15, 1965, page 2 7 ) . In brief, it proposes a limit on the amount of solvent which can be emitted per day by a facility. By specifying what solvents can and cannot be used, it rules out many of those commonly used in paint and other industries. Compliance costly. Industry has labeled the rule as impractical and too costly to comply with, and APCD authorities agreed to study their data further. The National Paint, Varnish and Lacquer Association sponsored the study. CMA and APCD reviewed and analyzed the original data compiled by APCD and conducted addi-
Solvent users will have to install equipment to control emissions
en' w Los Angeles smog
38 C&EN APRIL 18, 1966
tional tests on some solvents. A revised rule that may be more palatable to industry will be drawn up next month. No matter what shape it finally takes, Rule 66 will have widespread impact. In all likelihood it will serve as a pattern for similar rules in other areas of the country. APCD, however, recommends that other communities not adopt Rule 66 because it is based on, among other things, Los Angeles County's unusual location and climate. Nevertheless, APCD has been receiving inquiries from industries and communities about the solvent standard, and the San Francisco area is likely to be the second region to adopt such controls. Faced with Rule 66, industrial paint makers may have to reformulate many of their products. Paint users may have to install equipment to control their solvent emissions. Others affected include industrial users of degreasing solvents; plastics, rubber, and adhesive makers and users; printing ink firms; and dry cleaners. Organic solvents are the second largest contributor to emission of organic materials in Los Angeles County. According to APCD, in January 1965 they accounted for about 550 tons per day of such emissions out
of a total of 2755 tons from all sources. Motor vehicles are the major culprits, contributing 1930 tons per day. Rule 66 as proposed last November would require any facility using organic solvents to cut emissions to 50 pounds per day, or to 10% of its actual weight of present emissions, whichever is greater. Excluded are the manufacture, transport, and storage of solvents. However, the rule covers in-plant use of solvents and use of products containing solvents. Exactly which solvents can and which can't be used and under what conditions gets complicated under the rule. A few are exempt on the basis of their low order of photochemical reactivity and can be used under any conditions. Many others are also exempt but only if used in a system below 125° F . A third group is nonexempt and can't be used at all except in small amounts in blends with exempt solvents. Some exemptions. Exempt under any conditions are carbon tetrachloride, perchloroethylene, and saturated fluorocarbons. Solvents which are exempt, but only if used below 125° F., include aliphatic, naphthenic, and aromatic hydrocarbons that have no branched structures or substituent groups other than halogens. Also in this group are alcohols, esters, and ethers. Nonexempt solvents include certain olefinic, certain aromatic, and branched aliphatic and naphthenic hydrocarbons. More than half of the solvents used in the Los Angeles area are aliphatic hydrocarbons, particularly hexane
"A person shall not use organic solvents, or any material containing organic solvents, in any article, machine, equipment, contrivance or facility unless the total emissions of organic materials into the atmosphere in any one day do not exceed SO pounds, or unless all such emissions are reduced either to not more than 50 pounds or to not more than onetenth the actual weight of such emissions . . . "
EXEMPT. Most solvents used by dry cleaners in equipment such as these technicians are checking would be exempt under Rule 66
(normal and iso-) and mineral spirits. Under the present proposed rule hexane is exempt below 125° F.; mineral spirits is nonexempt because it usually contains branched paraffins or aromatics in nonexempt concentrations. The next most widely used solvents are the aromatic hydrocarbons, xylene (mixed isomers) and toluene, both nonexempt. Third are the alcohols, which are exempt below 125° F. Also used in large amounts are the halogenated hydrocarbons trichloroethylene (nonexempt) and perchloroethylene (exempt at any temperature). Such ketones as acetone and methyl ethyl ketone are consumed in con siderable quantities and are exempt below 125° F. Industry sees many problems with Rule 66 in its original form. Replac ing nonexempt solvents with exempt ones will increase costs. For instance, aliphatic and aromatic hydrocarbons now widely used range from 18 to 30 cents per gallon. Costs of re placement solvents—ketones, esters, ethers—would be anywhere from two to five times higher. In the case of industrial paints, some base resins may have to be modified because for paints used over plastic, for example, replacement of xylene with an oxygenated solvent would not work. Most coated parts require an oven bake at temperatures above 125° F., at which point almost all sol vents become nonexempt. Also, it will take paint makers time to come up with suitable reformulations. For ex ample, replacing aromatics, such as xylene and toluene, with exempt sol
vents would be a big problem. Blends of η-paraffins and oxygenated solvents could be substituted but they would be costly. Limited uses. Some water-thinned industrial coatings are now available but their end uses are limited. Ex terior durability, gloss, wear and gloss retention, flexibility, and production line application properties of these systems still don't measure up to cur rently used industrial paints. And the raw materials costs of water-thinned paints are higher. The adhesive industry can use hexane as a resin carrier. Tire makers could go to 9 0 % - 1 0 % blends of hexane and aromatics in their rubber cements. Both are now using nonexempt hydrocarbons. Mineral spir its, used at room temperature in sol vent degreasing, can be replaced with η-paraffins to the extent that they are available. Now-exempt alcohols, gly cols, and glycol ethers could be em ployed as solvents in printing inks, but they would cost two to four times as much as the currently used aliphatic solvents. Equipment control. Under Rule 66 industries unable to switch solvents would have to use control equipment such as activated charcoal adsorbers or afterburners. The cost of operat ing adsorption equipment would be high, ranging from 1 to 5 cents per pound of solvent adsorbed, depending on the size of the system and other factors. And afterburners have an appreciable fuel cost. The after burner is simply an insulated chamber in which the solvent exhaust stream is
continuously heated, mixed, and re tained long enough for the combusti ble vapors to be oxidized and burned. This requires addition of heat by burning a fuel like natural gas. The CMA-APCD study was initi ated in late February. The plan was to review and analyze the data com piled by APCD and to conduct addi tional tests on some of the solvents affected by the rule. In its original smog chamber stud ies, APCD found that aromatics (ex cept benzene) and chlorinated hydro carbons (except perchloroethylene) contribute strongly to eye irritation and ozone formation. Except ben zene, perchloroethylene, and acetone, all of the solvents and solvent mix tures tested produced significant amounts of ozone by irradiation in the presence of oxides of nitrogen. The joint CMA-APCD study has in cluded chamber tests on a large num ber of solvents, including xylene, toluene, mineral spirits, normal and isoparaffins, isophorone, naphthenes, trichloroethylene, methyl isobutyl ke tone, and Stoddard solvent (a petro leum distillate). Based on the re sults of these tests, CMA has hopes of extending the amounts of nonexempt solvents which can be used in blends with the exempt solvents. Also, some of the nonexempt solvents may be moved to the exempt list, CMA says. Tests were also carried out on the 125° F. requirement to determine whether or not the temperature limit can be raised. Vapor emissions from bake ovens are being studied and it is very likely that a revised rule will cover effluent from ovens. A modified Rule 66 will probably be ready for review in May. The new rule must be submitted to the County Board of Supervisors who must give proper notice of a public hearing. Af ter the hearing, the board would vote on the proposed rule. Many feel that a modified rule will be adopted this year.
Supplies Tighten in Chlorinated Solvents
RECOVERY. Solvent recovery equipment, such as this vapor absorber made by VIC Manufacturing, would be needed to control solvent emission
The increased tempo of industrial ac tivity and the step-up in production of military equipment caused by the war in Vietnam have combined to create tight supplies and higher prices for chlorinated solvents. Methylene chlo ride and 1,1,1-trichloroethane are al ready in critical supply. Dow Chemi cal is selling both on allocation, and Diamond Alkali is meeting only con tract orders for methylene chloride. Trichloroethylene is also beginning to feel the pinch. Most other producers of methylene APRIL 18, 1966 C&EN 39
