Sharon Spielman gives us more on thermal fluid
As I discussed in last month's column, changing the fluid in your hot oil system can be dangerous. David Dowlen, assistant service manager at Heatec Inc., Chattanooga, Tenn.; Doug Irvine, engineering manager, thermal fluids, at Petro-Canada Lubricants, Mississauga, Ontario; and Jim Oetinger, sales director and chief chemical engineer at Paratherm Corp., Conshohocken, Pa., talked with me about specifics actions that can be followed while performing this task to ensure the safest change.
In this month's column, I continue this series with specifics about the vapor pressure curve, a nitrogen purge system and draining the system. In addition to MSDSs (discussed in last month's column), a copy of the vapor pressure curve for the fluid being used also should be available, according to Dowlen. “When dealing with high temperature [typically above 375oF (191oC)], it is necessary to apply an inert gas such as nitrogen to the expansion tank. The higher the operating temperature, the higher the nitrogen pressure will be needed to keep the fluid in a liquid state rather than flashing into a vapor,” he says.