Q: Why do you claim that FR3 fluid is so much safer than mineral oil?
It can still burn, can’t it?
A: Simply put, mineral oil transformer fires are a daily occurrence. Even a single incident can cost property owners tens of millions of dollars. Cooper Power Systems has never received a report of an oil fire involving any of our fire-resistant fluids.
While the energy from electrical arcing often ignites mineral oil, (fire point approx. 160° C), numerous tests by FM Global® show that the same arc energy is not sufficient to ignite dielectric coolants with fire points at or above 300° C.
With the highest flash and fire points of any dielectric coolant, (330° and 360° C, respectively) FM considers it extremely unlikely for a pool fire to develop for FR3 fluid. They’re so confident that they have reduced recommended minimum clearances to as low as 3 feet.
Q: What other independent agencies have verified the fire safety of FR3 fluid?
A: Test results from FM Global, Underwriters Laboratories®, Doble Engineering and the US EPA have also verified the key fire safety properties of FR3 fluid. It is an FM Approved, UL® Classified fluid for indoor and outdoor installations per NEC® 450-23 and meets the criteria as a “high fire point fluid” per NESC.
Q: But aren’t dry types safer?
A: Not according to fire incident reports. Dry types, including cast resins, can and have failed catastrophically due to flammable vapors produced by the vaporization of metal. Furthermore, dry types do not have the preventive maintenance tool of DGA (Dissolved Gas Analysis) to predict unseen problems. As mentioned above, there have been no reported oil fires involving any Cooper Power Systems fire-resistant fluid in its quarter century of experience. And units that meet the UL and FM listed transformer requirements help prevent tank rupture from internal arcing as well.
Q: Does FR3 fluid auto-ignite if it reaches its 360° C fire point?
A: No, even at 360° C it will not ignite without an external ignition source. It is extremely unlikely for the dielectric coolant in a severely overloaded transformer to exceed 130° C, so the margin of safety is very high.
Q: After retrofilling a transformer, what fire safety concerns should remain due to residual mineral oil?
A: As incredible as it seems, even with a contamination of up to 7.5% mineral oil, FR3 fluid key properties remain unaffected and maintains a fire point of over 350° C, including maintaining a fire point rating of over 350°C (Proper retrofilling should result in less than 5% residual mineral oil).
Q: Does the use of FR3 fluid eliminate the need for fire safeguards that are required when using mineral oil?
A: Typically yes, and the savings can be very substantial. This includes protective barriers like safety walls, as well as deluge systems and other fire suppression equipment. It also includes significantly reducing the minimum clearance distance between transformers and buildings.
