Vacuum system, operation safety

It is highly desirable that a portable safety screen suitably located should be provided between the operator and the distillation unit and vacuum system illustrated. 

The acetylene cylinder must be chained securely to the wall or laboratory bench. Work on a vacuum system requires a preliminary review of procedures and careful execution in order to avoid damage to the apparatus and possible injury from broken glass in addition, the liquid nitrogen used for cold traps must be handled properly (see Appendix C). Safety glasses must be worn. Acetylene is flammable no flames can be permitted in the synthesis area. Take great care not to allow oxygen condensation to occur in the presence of acetylene (potentially explosive). Carry out as many operations as possible in a fume hood. Dispose properly of excess CaC2. 

In general, most reactions involving hazardous or toxic vapor phase precursors are operated at reduced pressure from a safety perspective. Additionally, the enhancement of kinetic steps often occurs by operating at reduced pressure. As indicated in the individual chapters of this book, many reaction schemes involve operation at low pressure, and, therefore, care must be taken with the vacuum system, its maintenance, and the exhaust of a reaction co-product stream. For specific applications of low pressure operation, the reader should consult the appropriate chapter on the material of interest. 

A key danger in the retrospective approach is to fall into the trap of conveniently building the safety argument around selective evidence which happens to be at hand. To do so runs the risk of forcing the safety case to articulate an artificially rosy picture of the world. It can be easy to assume that a much-loved system that has been in operation for many years must be intrinsically safe. That is not to say that it is unsafe but one should actively question whether the data which happens to be available can truly and objectively substantiate the safety case s claims. In some circumstances it may be appropriate to undertake the hazard assessment in a virtual vacuum of operational knowledge perhaps involving personnel who are somewhat removed from its day-to-day business. In this way appropriate controls can be developed and more objectively be tested to determine whether they can be traly validated. 

For the user, this knowledge means that the desired operating pressures cannot be achieved with the selected vacuum technology or that the operational safety of the vacuum system may be impaired. 

Discuss the potential hazards associated with the operation of pressure and vacuum systems, and the special safety precautions required. 

The condensate demineralizer and condensate filter demineralizer clean the condensate system and feedwater system (called the main coolant system in safety design). The reactor is also cleaned with the reactor clean-up system. It should be mentioned that the reactor cleanup system is used for only the startup, and the coolant is purified in the condensate system during the once-through operation as done in FPPs. Also, as in BWRs, the condenser is vacuumized in order to prepare it for start up. 

The TGA apparatus becomes very hot and caution should be exercised while using it. In order to safely handle volatile materials or polymer decomposition products which may be irritating and harmful, it is suggested that a gas bubbler be constructed to scrub the gaseous effluent from the instrument (Fig. 15.5). Care must be taken to prevent excessive gas pressure from building up if the system is being operated under vacuum or with gases, both inert and flammable. Consult the instrument operations manual for any special safety instructions. 

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