“The ecological cooling system with vacuum control for laboratory
Rotary Evaporators

Strike/CryoChiller Evaporation System
One of the most common and frequent operations in a chemistry or biology laboratory is that of removing the solvent from reaction products. Generally this operation is done using a rotating evaporator together with a vacuum unit. Despite its simplicity, this system can be a source of risk for the operator, due to the rotating glass components under a vacuum and the electrically heated oil or water temperature bath.

These concerns for safety lead to the creation of the Strike, the Steroglass safe rotating evaporator that provides total protection for the operator. The transparent protective shield offers maximum protection against breakage and sprays for both the operator and the working environment, thanks also to the electronic safety device which prevents the flask from rotating when the shield is raised (in conformity with CE machine safety standards, which require that moving instruments be protected to avoid risks to the operator). The plasticized external glass components keep any fragments expelled inside the protective plastic in the event of a possible explosion. The thermostat-controlled temperature bath set in the steel chassis has a planar heating element at the bottom of the tank which eliminates any possibility of electrical shock to the operator.

Up to this point we have looked at physical hazards that can arise during the use of a rotating
evaporator; however, one must not overlook the harm caused by commonly used organic solvents, as concerns both the operator’s health as well as the impact on the environment. These substances, also known as volatile organic compounds (VOCs), have been receiving attention for some time, given their many noxious and toxic effects on people and the environment (see Appendix I): in recent years, a number of European directives have been issued in order to regulate the use and immissions of VOCs. Consequently, there is a definite need to succeed in optimizing the processes that lead to the vaporizing of organic substances so as to limit their immission into the surrounding environment.
The Strike rotating evaporator guarantees a perfect seal, thanks to its exclusive self-lubricating, anticorrosive mechanical seal system and the evaporation flask clamping system; all the same, to keep the releasing of VOCs to an absolute minimum, the evaporation processes must be carefully controlled by regulating the operating pressure and the cooling temperature.

This is possible with the use of the Steroglass CryoChiller, an ecological cooling system with a
controlled vacuum. Numerous laboratory tests (see Appendix II) show how the use of the
CryoChiller gives almost total recovery of the evaporated solvent (as opposed to what happens
when the vacuum and coolant temperature are not controlled). In most labs, the rotating evaporator is connected directly to a vacuum pump (water, oil, or diaphragm type…) in such a way that the working pressure cannot be controlled. The cooling liquid used is very often tap water, which can exceed a temperature of 20°C. In these conditions, depending on the volatility if the liquid being evaporated, a quantity of solvent of over 95% of that being evaporated will be released into the environment, an enormous percentage considering the toxicity of VOCs! By comparing Table 1 with Tables 2, 3, 4, and 5, you can see just how important it is to control the pressure in order to substantially limit contamination from VOCs. The temperature of the coolant also plays a fundamental role: it is not easy to condense organic solvent vapors and then to succeed in keeping them inside the collection flask of a rotating evaporator; the glycol mixture cooled to 5°C is a fully satisfactory means for achieving this. It is interesting to note how when working with medium vacuums, the use of coolant chilled by the CryoChiller gives a solvent condensation from 5 to 30% greater than tap water (compare Table 5 and Table 3). If this is not enough for totally knocking down the VOCs, the CryoChiller is also equipped with a pre-pump trap (capable of keeping any solvents derived from turbulent boiling from reaching the pump) and with a post-pump environment-saving trap (with coolant, essential for the condensation of any vapors drawn by the pump, to avoid their release into the environment).