Control of VOCs: following Ohio's lead; the experiences of Ohio metalcasters in revising state VOC control rules for chemically bonded core- and moldmaking processes can serve as a lesson for the industry to follow.

In 1995, some Ohio metalcasters were being scrutinized by the Ohio EPA for potential air quality issues resulting from the emission of volatile organic compounds (VOCs) from core- and moldmaking operations. Related to an Ohio air pollution control requirement known as the "8 and 40" rule, the potential application of this rule threatened to impose an unnecessary economic burden on foundries in the state.

In response, the Ohio foundries banded together under the auspices of the Ohio Cast Metals Assn. (OGMA) and formed a committee to work with the Ohio EPA to exempt these foundry processes from the requirements of the rule. After the committee initiated negotiations with Ohio EPA, it commissioned a study to evaluate the technical and economic feasibility of applying VOG controls on these processes.

Since accurate emission factors were not available, the study included the development of new emission factors for phenolic urethane coldbox (PUCB) and phenolic urethane nobake (PUNB) core- and moldmaking processes. These emission factors have since been sought after and used by many foundries across the country.

This article examines the situation that threatened Ohio metalcasters and how it was solved. While this effort was Ohio-specific, it serves as a model for similar analyses that are required in air permitting processes in other states. Both the technical and economic feasibility analysis in the study can provide guidelines for others, regardless of jurisdiction.

Discerning the Problem

After several meetings, the Ohio foundry committee and Ohio EPA concluded that certain core- and moldmaking operations were subject to an Ohio air pollution control requirement, the "8 and 40" rule for emissions, that applies to operations using liquid photochemically-reactive organic materials. The rule requires 85% control of organic materials from any operation if it emits more than 8 lb/hr or 40 lb/day of organic materials.

Both Ohio metalcasters and Ohio EPA agreed that a literal application of the "8 and 40" rule to Ohio foundries had the potential to cause an excessive economic burden, adversely affecting the foundry's ability to compete. Following months of discussion, Ohio metalcasters and Ohio EPA signed a Memorandum of Understanding. The main elements of the memorandum were:

* Resin suppliers would develop more reliable emission factors based on limited laboratory testing of the most common or representative binder systems affected by the "8 and 40" rule;

* OCMA would conduct a study to determine the cost effectiveness of controlling VOC emissions in accordance with the rule for "typical" core- and moldmaking operations;

* While the above studies are in progress, Ohio EPA would process permits using a U.S. EPA published emission factor and exercise enforcement discretion with respect to the "8 and 40" rule;

* After completion of the study, Ohio EPA would determine if a rule change, company-by-company relief, or variances were warranted based on the results of the study.

Suppliers in Action

The three major resin suppliers to Ohio at that time, Ashland Chemical Company, Borden NAR and Delta H-A, formed a subcommittee to complete the following three tasks:

1. Identify binder systems that may be "photochemically-reactive" and subject to the "8 and 40" rule.

2. Develop a protocol to determine emissions of those binder systems that are photochemically-reactive.

3. Conduct testing, following the developed protocol, to estimate emissions for the identified binder systems.

Using the developed protocol, the resin suppliers evaluated the VOC emissions from Ohio foundries' most commonly used PUCB and PUNB binder systems. The protocol called for a round robin double-blind laboratory study using "weight loss" as the method for evaluating VOC emissions.

A report was provided to the Ohio EPA outlining the results of the emission testing program and recommended the following emission factors: 0.65 lb of VOC/ton of sand for PUCB binder systems and 1.17 lb of VOC/ton of sand for PUNB binder systems.

Several important aspects regarding the above emissions data must be noted, First, because of Ohio EPA requirements, the above data includes emissions that occurred during 12 hr of storage (following manufacturing). Second, the PUCB emission factor does not include emissions from the catalyst (the emissions from the catalyst are included in the cost-benefit analysis). For both PUCB and PUNB, the Part land Part II of the binder were added at a rate of 1% of sand (and split 55/45% between Part I and Part II, respectively). For PUNB, the catalyst was added at a rate of 0.5 g per 16.5 g of Part I.

In March 1997, Ohio EPA responded to the recommendations, agreeing to the proposed emission factors. The next step was to determine what might constitute "typical" core- and moldmaking operations. More than 50 Ohio foundries were contacted by members of the committee, The five scenarios shown in Table 1 were chosen.

Technical Feasibility

The amount of exhaust air required for each of the five scenarios was an important parameter for both the technical and economic feasibility analysis. The amount of exhaust air was established through discussions with core machine vendors, making engineering estimates and to a lesser extent using engineering judgement.

To provide for total capture of the VOCs, the PUNB production scenarios and all storage areas were designed following the criteria established for permanent total enclosures. In these scenarios, a dilution ventilation system comprised of roof exhausts and fresh make-up air units was installed. Exhaust and make-up airflow rates were calculated using the dilution ventilation equations listed in the American Conference of Governmental Industrial Hygienists Industrial Ventilation Manual and the American Industrial Hygiene Assn. Engineering Field Reference Manual.

The following technologies were considered for the control of organic emissions: thermal oxidation, catalytic oxidation, carbon adsorption, concentrators, biofiltration, condensers and scrubbers. Following a review of the exhaust flow rate, the VOC concentrations and other factors, three emission control technologies were selected for each production and storage scenario.

For PUCB production, recuperative thermal oxidizers, recuperative catalytic oxidizers and carbon adsorption were the chosen technologies and for all other production and storage area concentrators, regenerative thermal oxidizers and biofiltration were chosen as the best methods of control.

Economic Feasibility

Following Ohio EPA's concurrence on the selected emission control alternatives, a detailed cost-benefit analysis was performed for each scenario in accordance with EPA guidelines. Capital costs for emission control equipment used in the analysis were based upon actual quotes obtained from equipment vendors. Capital costs associated with constructing the enclosure and ventilation sys tem for each scenario were based upon a combination of vendor quotes and engineering estimates.

To develop final costs, key assumptions were made regarding the facility layout and costs associated with energy, installation of control equipment and labor. Table 2 provides a summery of the cost-effectiveness analysis results.

Ohio EPA Exemption

Following a review of the cost-effectiveness study report, Ohio EPA agreed that the cost effectiveness numbers of VOC controls on core- and moldmaking operations using PUCB and PUNB binders greatly exceeded the acceptable range. Based on this, Ohio EPA concluded that VOC controls for these processes were not economically feasible. Ohio EPA promulgated a rule that exempted new core- and moldmaking operations in Ohio foundries that use either PUCB or PUNB binder systems from the VOC control requirements of the "8 and 40" rule provided certain conditions were met.

For More Information

This result was a major victory for Ohio foundries, as it removed an unnecessary regulatory and economic burden. In addition, the process of obtaining the exemption was accomplished in close cooperation with Ohio EPA, paving the way for future cooperative efforts.

Visit www.moderncasting.com to view "VOC Issues for Foundries," A. Franks, 8th AFS Environmental Health and Safety Conference, 1996, p.363-368.

"Modeling Foundry Air Emissions," P. Kauffmann and R. Voigt, MODERN CASTING, May 1997, p.53-55.

Table 1

Scenarios for Cost-Effective Analysis


Scenario #1  PUCB core production and storage
             Production rate of 7.35 tons/hr for 8 hr/day
             VOC emission rate of 40 lb/day
             Core storage for 12 hr after production

Scenario #2  PUNB core production and storage
             Production rate of 4.28 tons/hr for 8 hr/day
             VOC emissions rate of 40 lb/day
             Core storage for 12 hr after production

Scenario #3  PUNB mold production and storage
             Production rate of 11.97 tons/hr for 16 hr/day
             Mold storage for 12 hr after production

Scenario #4  PUCB core production and storage
             Production rate of 7.35 tons/hr for 16 hr/day
             Core storage for 12 hr after production

Scenario #5  PUNB mold production and storage
             Production rate of 18 tons/hr for 16 hr/day
             Mold storage for 12 hr after production

Table 2

Summary of Cost-Effectiveness Analysis

Operating Scenario                   Range of Cost
                                 Effectiveness ($/ton)

                    Scenario #1
Core Production                      37,000-82,500
Core Storage                        95,500-103,500
                    Scenario #2
Core Production                     159,500-178,500
Core Storage                        86,000-106,500
                    Scenario #3
Mold Production                      56,000-76,500
Mold Storage                         53,000-72,000
                    Scenario #4
Core Production                      24,500-85,000
Core Storage                         58,000-65,500
                    Scenario #5
Mold Production                      43,500-59,500
Mold Storage                         39,000-54,000

About the Authors

Kim Meyers is the vice president of the OCMA. Jeet Radia is the senior vice presdient at Keramida Environmental, Inc.. Columbus, and has over 25 yr experience in industrial hygiene. Craig Schmeisser is a senior client service manager at RMT, Inc., Columbus. Russ Murray has served as the executive director of the OCMA since 1992.