Case study: fire protection of oil-filled substation transformers
| Client | Confidential UK client |
|---|---|
| Location | Heathrow region, United Kingdom |
| Sector | Electrical infrastructure and critical power |
| Result | Live transformers protected with Dryfoam in under an hour each, with zero downtime |
Challenge
In March 2025, a transformer fire at a UK National Grid substation caused an extended power outage at Heathrow Airport. International Airlines Group, the parent company of British Airways, alone reported an estimated $56 million impact on its operating profits.
The post-incident review identified a long-standing vulnerability: inadequate fire suppression for oil-filled transformers. The event prompted reviews of the UK's critical infrastructure, particularly data centers and electrical networks, and underscored the need for a fail-safe way to prevent transformer fires as replacement lead times grow: 2024 quotes ranged from 1.5 to 4 years (National Infrastructure Advisory Council, Addressing the Critical Shortage of Power Transformers to Ensure Reliability of the U.S. Grid, draft report, June 2024).
The client wanted to protect live transformers from fire risk caused by oil leaks or damage, without costly shutdowns or heavy equipment. Once installed, the protection had to be passive and continuous, working on its own in the event of a leak.
Key requirements
- Eliminate ignition risk from leaked transformer oil
- Avoid complex piping, sensors or power systems
- Install quickly under operational conditions
- Maintain full spill containment capacity
Installation
Installation is usually simple: open a bag of Dryfoam and pour. This project added a challenge. Because it was a retrofit with a zero-downtime requirement, some areas needing coverage were hard to reach. To cover them without removing equipment, the team introduced a thin layer of water into the catch basin so the Dryfoam beads would flow into low-clearance areas. Once the beads were in place, the water was drained, leaving a clean, dry installation. (Photography was prohibited on site.)
Results
| Requirement | Outcome |
|---|---|
| Eliminate ignition risk from leaked transformer oil | Any oil leak now flows through the Dryfoam blanket to the bottom of the catch basin, passively contained and unable to ignite. |
| Avoid complex piping, sensors or power systems | A passive system, installed by hand with water and bags of product. |
| Install quickly under operational conditions | Installation took less than an hour per transformer, using a new technique for retrofits. |
| Maintain full spill containment capacity | Dryfoam conformed to the existing equipment and met full containment needs. |
Lessons learned
- A thin water float is a workable way to install Dryfoam when retrofitting or covering hard-to-reach areas.
- The installation met current fire safety recommendations for oil-filled transformer containment, a new application for Dryfoam.
- Fast installation with zero downtime is possible while the equipment stays in operation.
More
Case study (PDF), transformer fire protection, Dryfoam specifications and testing, and the coverage calculator for sizing a catch basin. For a technical conversation, email contact@dry-foam.com.