Alstom Chester

  • Company: Alstom Chester
  • Industry: Rail
  • Services: Oil Analysis, Advanced Investigation, Cloud-based Reporting
  • Location: United Kingdom
  • Cost-Saving: Avoided Critical Downtime

The Overview

A rail client identified a solid deposit on the fire switch of a 175 engine. The mechanical switch was providing false pressure readings due to the button sticking. Further investigation discovered that the liquid inside a fire bottle was leaching through into the switch, causing metallic components of the switch (i.e. copper and zinc) to corrode and fuse with other components of the switch.

The Situation

A renowned company operating in the rail industry approached us regarding their oil analysis service after identifying a serious issue across their entire fleet of trains.

The Challenges

A solid deposit was discovered on a fire switch which was mounted to the cooler raft of a 175 engine on the operator’s diesel multiple unit passenger trains.

The mechanical switch was providing false pressure readings due to the button sticking; a potentially critical fault that required urgent investigation.

The Solution

After undertaking routine oil analysis on the black deposits, the results appeared inconclusive. It was recommended that a more advanced analysis technique, SEM-EDX (Scanning Electron Microscopy Energy Dispersive X-ray), to determine the source of the black residue.

The Results

The SEM topography outlined the elemental composition of the black deposit to be mainly organic matter (carbon and oxygen) and brass (copper and zinc).

Upon further investigation, the contents of the fire bottle were determined to be TRIDOL S 6% AFFF, which contains diethylene glycol monobutyl ether. This is thought to be the likely source of the carbon and oxygen.

The liquid inside the fire bottle was believed to be leaching through into the switch, which when interacting with moisture in the air caused the metallic components of the switch (i.e. copper and zinc) to corrode and fuse with other components of the switch.

The rail transport company worked with the supplier of the fire bottles to identify a switch to eradicate the issue and installed the new switch on every engine across their fleet.

The operator is now one of our largest customers and has implemented a managed oil analysis programme as part of their maintenance strategy.