Apparatus - Hydrothermal Technology - page 130

[138] . Several authors have discussed, in detail, major hazards with hydrothermal
autoclaves [37,139] .
Overheating of the furnace resulting from the malfunction of the control system
is a common reason for vessel failure. Hence, furnaces should be properly shielded.
Burns from hot vessels represent another major hazard with cold-seal laboratories.
If it is necessary to handle a hot vessel, it should be done by grasping the relatively
cool closure assembly wearing special insulated gloves.
Note that any vessel to be heated must never be filled completely with an
aqueous solution. Fluids expand on heating and are capable of generating extreme
pressures when further heated beyond the PT limits of the autoclave. It is criti-
cally important to calculate the thermal expansion of the aqueous phase and to
allow at least 20% of the total volume of the vessel for uncertainty or temperature
overturn. An apprenticeship in an operating hydrothermal laboratory is strongly
recommended to learn, to anticipate, and to cope with the dangers of such experi-
ments. For those planning to set up a hydrothermal laboratory, it is advisable to
visit other existing laboratories to review safety procedures as well as designs.
Therefore, autoclave maintenance and safety make hydrothermal experiments
quite expensive.

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