I have been observing the responses, and want to add one precaution, and bit of advice.
PRECAUTION: When I used silicone oils (and visited labs in which they were used) despite considerable care to avoid dripping, the floor (typically in front of a fume hood) becomes VERY slippery, with no "sheen" that provides a warning. I don't recall any falls, but I had some near misses. Attempts to wipe away the thin layer of silicone material are typically not successful.
ADVICE: Mechanical (e.g., stirring) and electrical temperature-control systems fail. Failure in the "heat-on" mode can create nasty problems. For overnight or remote unattended heating of reaction/reflux vessels (heated via any of the means you folks have mentioned) it is a good practice to install an independent over-temperature sensor in the vessel. The over-temperature sensor will automatically open the circuit of the heating system if the temperature in the vessel exceeds a selected value. I am aware of a laboratory fire that started on an early Saturday morning because the "known to occasionally fail" thermostatic control device for heating an oil bath failed in the "on" mode. There was no independent over-temperature sensor.
In a domestic application of this principle, I installed an over-temperature device (fusible link in a circuit) that will automatically shut off my whole house fan (that exhausts to the attic and then to the outdoors) if the attic temperature exceeds a temperature indicative of a house fire.
Retired in Illinois
Thursday, January 31, 2013 12:20:04 PMSubject:
[DCHAS-L] oil baths use
I was wondering if I can tap on the group expertise and wisdom on the use of Oil baths. We have had a few small fires due to overheating or faulty thermostat. In your opinion, how often oil baths must be changed? What type of oil (not too expensive) is recommended? What do you suggest replacing them with ? I have heard: beads, sand etc.. Please share any experience you may have with oil baths substitutions. Do they work to heat up solvents evenly?
Again, thank you for all ideas or suggestions you may have. Keep up the great work you do.
Yung Morgan, MsPH
Industrial Hygiene Services
Environmental Health and Safety
117 Draper hall
UMASS,Amherst MA 01003
phone (413) 545-2682
Fax (413) 545-2600
email : pmorgan**At_Symbol_Here**ehs.umass.edu