Application Advice

ASA undergoes the normal reactions of acid anhydrides. Of particular interest in conjunction with sizing is the reaction with alcoholic hydroxy groups to yield an ester, and the hydrolysis with water. Both reactions occur in the papermaking system. ASA is highly reactive, and the reactions proceed rapidly and irreversibly. Although this would provide satisfactory development of sizing on a paper machine, the hydrolysis of ASA is undesirable. The hydrolysis accelerates with pH, time, and temperature and leads to deposits and runnabiHty problems on the paper machine. In order to Hmit the hydrolysis of ASA emulsions, the pH can be lowered immediately after the emulsification by addition of aluminum sulfate. 

High solids retention is extremely important in ASA sizing. If this is guaranteed and ASA is applied correctly, a relatively small dosage of 0.1-0.2% based on solid furnish is required to produce the desired degree of sizing. Careful selection of retention aid is therefore an important part of the ASA sizing process. 

The great advantage in favor of ASA is the high rate of cure in comparison with AKD size. The reaction with cellulose hydroxy groups takes place rapidly in the dryer section of the paper machine at less than 5 % web humidity. More than 90% of the attainable sizing potential is, in most cases, achieved before the size press unit. The reaction rate is influenced by the same parameters as the hydrolysis, that is primarily by pH, previous residence time, and stock temperature. 

The best conditions obviously depend upon the balance between the reaction rates with cellulose hydroxy groups and hydrolysis of ASA, and optimum sizing can be achieved at neutral rather than at higher pH, depending on the fuU set of system conditions. 

PSA For internal sizing (wet-end addition) quantities of 0.5 to 1 % (soHd product on dry paper stock) are required to obtain a hard sized sheet, depending on the nature of the stock. The product is best metered continuously to the stock suspension before the pressure screens. The polymer must be prediluted with an in-line mixer to a concentration of 1-5 %. A cationic retention aid, e. g. modified polyethylenimine, cationic polyacrylamide or polyvinylamine improves the fixa-tion/retention and therefore gives a better sizing effect 

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Locks There is a wide variety of locks and security fittings, many with special applications. Advice from locksmiths or other security experts should be taken before deciding upon a type of lock, but, wherever practicable, only those locks that require a key to lock and unlock them should be chosen. BS 3621 establishes a useful minimum standard but is not applicable to all lock types ... 

The mechanical properties reported in the literature for molybdenum and its alloys are frequently at variance. That this should be so is not surprising as the properties of molybdenum and its alloys are greatly affected by the prior history of the material, both thermal and mechanical. Far too often values are used without reference to the sources of the material, various states of heat treatment, etc. When mechanical properties are an important feature of the design application, advice should always be sought on the suitability as only the manufacturer has the complete data on the history of his own product. Physical and some typical mechanical properties given for general guidance are shown in Tables 5.2 and 5.3. 

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Practical resistance occurred very early in the history of fungicides, but since the 1980s advisors from universities, regulatory authorities, farmers and farmers advisors and the agrochemical industry have learnt to deal with and to recommend practical application advice, alternating spraying recommendations and application methods and mixtures of fungicides to prevent yield losses caused by resistance development. 

If the above guidelines are followed, it is possible to ensure the safe use of adhesives and protect the health of those employed in their manufacture and application. Advice on storage and handling of adhesives is available from the manufacturers or general texts. ... 

Traditional PAHs separations by reverse phase (RP)-HPLC is conducted using gradient elution, mainly with acetonitrile water mixtures and sometimes with methanokwater mixtnres. RP-HPLC on chemically bonded Cig phases has been widely used in the environmental analysis of PAHs. Up to date, a wide variety of brands of HPLC columns is available for PAHs determination. Packed columns are rarely used in contemporary GC methods for PAHs, being practically 100% of applications carried out with capillary columns. Many commercial brands of GC and HPLC include in their web pages information related to best columns to work with in a specific application, advices to optimize the best gradient elution, and even suggestions for troubleshooting. 

Tank/soil potential measurements cannot be made on objects to be protected with very high coating resistances which are found in rare cases of defect-free coating, and particularly with resin coatings. Off potentials change relatively quickly with time, similar to the discharge of a capacitor, and show erroneous values that are too positive [8]. This is the case with coating resistances of 10 Q m. If there are defects, the resistance is clearly much lower. The advice in Section 3.3.2.2 is then applicable for potential measurement. 

Advice should be sought from the supplier as to the best type of control to suit a particular application. 

Unless a thermostatic expansion valve is very tightly rated, the system will operate satisfactorily at a lower condensing condition in cool weather, with a gain in compressor duty and lower power input. A growing awareness of energy economy is leading to more careful application of this component. Suppliers are ready to help with advice and optimum selections. 

The application area is so large that no cookbook advice would be useful. Each type of application must have the potential failure evaluated, the economics calculated, the degree of assurance of performance set, the extent of required testing determined, and the product designed and evaluated to meet the criteria established. There are sources of data available on which to base the approaches to the requirements, but the final combination of factors must be determined by the designer. 

Thus, a good source of potential revenue for products and services exists in the multitude of smaller boiler-houses to be found operating around the globe. It is here that practical advice is most often needed concerning the suitability and correct application of chemical treatments, the regular interpretation of analytical results obtained, and the strategies to be employed to maximize efficiency and reduce costs. 

The results of environmental monitoring exercises will be influenced by a variety of variables including the objectives of the study, the sampling regime, the technical methods adopted, the calibre of staff involved, etc. Detailed advice about sampling protocols (e.g. where and when to sample, the volume and number of samples to collect, the use of replicates, controls, statistical interpretation of data, etc.) and of individual analytical techniques are beyond the scope of this book. Some basic considerations include the following, with examples of application for employee exposure and incident investigation. 

All the countries use external experts or committees to help with the assessment of applications. However, their number and area of expertise differ from country to country. In most countries, the experts merely provide advice, while in some they also have a decision-making role. From the point of view of management, it would be... 

In Estonia, however, as many as 17% of the applications are withdrawn Ifom the process. Rejection rates are highest in Venezuela and Malaysia (30% and 29%, respectively). In both countries, withdrawal rates are small (0% and 3%, respectively). In Australia in particular, the number of applications withdrawn before a final decision has increased significantly in the past four years. This increase in withdrawals is probably a result of the way in which the registration system now operates, with a proposed decision to reject being made by the Delegate, prior to obtaining formal advice from the Australian Dmg Evaluation Committee. 

The AIChE method was developed from measurements on binary systems. The AIChE manual should be consulted for advice on its application to multicomponent systems. 

Frequently the physician is called upon to render professional advice or service on health problems involving these toxicants, only to find that there is little or no information upon which to base a rational conclusion. In other instances, he must piece together facts from a variety of widely scattered sources. Too often this information is of a limited nature and not applicable to the situation at hand or is so controversial and inconclusive in character as to render a reliable judgment impossible. As a consequence, the physician must resort to symptomatic measures which are often unsatisfactory because of the difficulty of relating symptoms to causative agent. At the same time, he is... 

There is general advice that the manufacturing process should be described but not so comprehensively as to necessitate frequent variation application for relatively minor changes. The details submitted in the application are binding and will need formal approval before they can be changed. Manufacturers are expected to have an appropriate change control system to ensure that this is undertaken appropriately. 

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