Transformer fire protection

Dryfoam protects oil-filled transformers at the source: a layer of engineered beads fills the catch basin, and any oil that leaks flows down through the beads to the bottom of the basin, contained beneath them and unable to ignite. It needs no water, piping, sensors, pumps or power, so once installed it protects the transformer continuously, on its own.

Why transformer fires matter now

In March 2025, a transformer fire at a UK National Grid substation caused an extended power outage at Heathrow Airport; International Airlines Group alone reported an estimated $56 million impact. The post-incident review pointed to inadequate fire suppression for oil-filled transformers. Replacing a transformer is slow, too: 2024 quotes for power transformers ranged from 1.5 to 4 years, according to the National Infrastructure Advisory Council. For substations, utilities and campuses running heavy AI loads, a transformer fire means a long, expensive outage.

How do you prevent a transformer fire without water or foam?

Flammable liquids don't burn; the vapors above them do. Dryfoam covers the oil's surface and suppresses those vapors, so leaked oil in the basin can't ignite. Each bead carries oil-phobic, water-phobic and intumescent coatings; if flame reaches the surface, the top beads form a sacrificial crust that protects the beads and oil beneath. Nothing needs to detect a leak or switch on.

Can it be installed on live transformers?

Yes. In a retrofit near Heathrow, Dryfoam was installed under live transformers in less than an hour per transformer, with zero downtime. Installation is usually as simple as opening bags and pouring; where equipment left little clearance, a thin layer of water was added to the basin so the beads flowed into place, then drained, leaving a clean, dry installation. Read the case study.

Dryfoam beads filling the containment around the base of an oil-filled transformer.

Does it reduce containment capacity?

In the Heathrow-region installation, Dryfoam conformed to the existing equipment and met the site's full containment needs: leaked oil collects beneath the beads, at the bottom of the basin.

Bulk or outdoor bags?

Both work in transformer catch basins. Bulk beads pour from a supersack (1 m³, or 35 ft³, each). Outdoor bags are UV-resistant polyester mesh bags of beads, placed by hand, for exterior basins; a single layer of bags suppresses fire on transformer oil (outdoor bags cut sheet). The Dryfoam coverage calculator sizes either for your basin.

What about codes and approvals?

Dryfoam's UL listing (category CPHW, file EX27169) covers full-surface fires in fixed flammable and combustible liquid tanks and repositories; it is not a transformer listing. The Heathrow-region installation met current fire safety recommendations for oil-filled transformer containment. Check your site's requirements with the Authority Having Jurisdiction. See specifications and testing for the details.