Alternative Controls

EPA has established a procedure to allow use of alternative control measures instead of some of the control measures specified in SNURS. This was necessary because in some instances a SNUR s reliance on respirators may conflict with the Occupational Safety and Health Administration s preference for engineering controls, which would be an alternative control measure. If these alternative control measures are implemented the use will not be a significant new use. EPA will entertain applications from manufacturers, importers or processors who propose alternatives to measures to control worker exposure or environmental releases.Applicants must submit a request to EPA for a determination of equivalency to  

The request for a determination of equivalency must include the submitter s name, the chemical identity of the SNUR substance, a citation to the SNUR in the Code of federal Regulations, a detailed description of the planned use, specifications of the alternative worker exposure or environmental release control measure, an analysis justifying why the alternative provides substantially the same degree of protection as the control measure specified in the SNUR, and all previously unsubmitted test data on the SNUR 

EPA has proposed electronic filing regulations and if these go into effect then requests for determinations of equivalency filed after the effective date must be made using the ePMN software, and may be filed on paper, through CD, DVD, or EPA s Central Data Exchange (CDX) for one year after the effective date of the new rules, and thereafter must be submitted via CD, DVD, or CDX for the next year, and then only through CDX.  

The regulations require EPA to review requests for determinations of equivalency within forty five days, and mail determinations back to the submitter. The submitter can only begin to manufacture, import or process for a use involving the alternative control measures if the EPA determines that the alternative control measures provide substantially the same degree of protection as the SNUR controls. Any deviation from the terms of the EPA s approval will be a significant new use. 

Several of the standardized significant new uses expressly contemplate alternative control measures, subject to approval by the EPA. For example, if a mixture has two or more SNUR substances in it, the label must include the most protective measures, but the label may include alternative control measures if the EPA has provided a determination of equivalency.  

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Alternative Control Techniques Document Nitric and Adipic Acid Manufacturing Plants, EPA-450/3-91-026, EPA, Research Triangle Park, N.C., Dec. 1991. 

The main shortcomings of the pneumatic controller is its lack of flexibility when compared to modern electronic controller designs. Increased range of adjustability, choice of alternate control algorithms, the communication link to the control system, and other features and services provided by the electronic controller make it a superior choice in most of todays applications. 

It will be the responsibihty of industry to suggest alternative control approaches and demonstrate satisfactorily that the proposal is equivalent in pollution reduction, enforceabihty, and environmental impact to existing individual process standards. 

EPA is required to identify alternative control technologies for all categories of stationary sources of VOC or NOj that have the potential to emit 25 tons per year or more of either pollutant. 

Increasing steric bulk at one of the NHC side groups will cause interference with the active site of the complex and generate an amplifying effect on alternation control. A methyl substituted one-carbon spacer like in l-mesityl-3-((rR)-l-phenylethyl)-4,5-dihydroimidazol-2-yhdene is enough to dramatically improve the alternation rate [129]. In Fig. 3.31 the steric impact on monomer coordination for different situations is rationahsed. 

As indicated above, there is a relationship between particle concentration, equilibrium factor and the amount of highly mobile radioactive particles. Removal of the accumulation mode particles may decrease the decay product exposure, but increase the dose because of the high effectiveness of the "unattached activity in dose deposition. Thus, air cleaning may not succeed in lower risk unless both factors are taken into account. Jonassen explores electrostatic filtration in this context. Finally, design considerations are presented for a possible alternative control system using activated carbon in an alternating bed system. 

A particularly serious environmental problem facing densely populated areas of the world is that of air pollution. The problem is both pervasive and difficult to control. An important element of a rational approach to improve the situation is a reliable means for evaluating the air quality impact of alternative control measures. 

There are several alternative controller design methods that make more explicit use of a process model. We will discuss two of these below. 

All information has been supplied by the vendor and has not been independently verified. Biotiltration systems are relatively large when compared to alternative control technologies. PPC Biotilter reports that the removal efficiencies vary for each application depending upon the chemical composition and mass loading. 

System designs vary from application to application. However, when biofiltration is economically competitive to alternate control technologies, the delivered and installed capital cost falls within the range of 12 to 40/cfm design flow. This estimate is for a turnkey system that includes engineering, fabrication, installation, and startup (personal communication S. Standefer, PPC Biotilter, 10/97). 

Fig. 7.77. Alternative control loop configurations for a system with two inputs and...

There are two general principles regarding chemical migration, the purity of the foodstuff and the inertness of the material. The first principle, the purity of the foodstuff, is the raison d etre for the control of specific substances on the basis of known or suspected toxicity. Control can take the form of limitations on the quantity of substance permitted to migrate to foods or food simulants. Alternatively, control can be indirectly via a limit on the quantity of the substance permitted to be present in the finished material or article. These are termed migration limits and compositional limits respectively. 

Gasquez, J. (1988). Herbicide resistance in France. In Herbicide-Resistant Weeds and Alternative Control Methods. Commission of the European Communities. Proceedings of a Meeting of the EC Experts Group. Tollose, Denmark. 

Watson, A.K. (1992). Biological and other alternative control measures. Proceedings of 1st International Weed Control Congress. pp. 64-73. 

If operated on clean, dry plant air, pneumatic controllers offer good performance and are extremely reliable. In many cases, however, plant air is neither clean nor dry. A poor-quality air supply will cause unreliable performance of pneumatic controllers, pneumatic field measurement devices, and final control elements. The main shortcoming of the pneumatic controller is its lack of flexibility when compared to modem electronic controller designs. Increased range of adjustability, choice of alternative control algorithms, the communication link to the control system, and other features and services provided by the electronic controller make it a superior choice in most of todays applications. Controller performance is also affected by the time delay induced by pneumatic tubing mns. For example, a 100-m run of 6.35-mm ( -in) tubing will typically cause 5 s of apparent process dead time, which will limit the control performance of fast processes such as flows and pressures. 

Plantwide Control Structure There are several alternative control structures for this process, and there is no claim that the one developed is the best from whatever perspective you consider. What is claimed is that it provides effective base-level regulatory control of this process. 

An alternative control would be direct interaction between the electron carrier protein and the protein exchanger, but it is not clear that there is sufficient oxidase available to interact by direct conformational change with the exchanger molecules. 

An alternative control strategy fixes the reactor-inlet toluene flow rate [16]. Fresh toluene is fed into the condenser drum of the last distillation column, on level control. Production-rate changes can be achieved by changing the setpoint of the toluene reactor-inlet flow, or the setpoint of the reactor-inlet temperature controller. When this control structure is used, the whole range of conversion becomes stable. Drawing of this control structure is left as an exercise to the reader. 

Alternate Control Centers. Recognizing the unpredictable nature of a developing emergency, it is advisable to select at least one alternate on-site main control center. Both the MECC and the alternate on-site center should have backup power supplies. 

We now explore two alternative control structures for this process. 

Variable reactor holdup structure. An alternative control structure is shown in Figure 2.7. This strategy differs from the previous one in two simple but important ways. 

Several economic factors affect commercialization of mycoherbicides (54. 64). the ultimate consideration being the projected economic returns from the mycoherbicide. A pathogen that is prone to be unprofitable or unpredictable in this respect, whether due to small market size, cost of production and marketing, competition from other alternative controls, or efficacy, is unlikely to be developed or offered for sale by commercial enterprises. 

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