The background

Southern Rail needed to improve its Controlled Emission Toilets’ (CETs) pump out systems, which are now the rail industry standard expected by operators and train users alike.

Trains store effluent in large, secure tanks under the carriage instead of depositing it directly onto the tracks.

A CET pump out system is then required to suck the effluents out and discharge to the main sewage system.

The challenge

Southern Rail was having problems at five of its depots across its network. With the existing system, the pumps were prone to blocking and ragging up.

Selwood was called in to suggest solutions to the problem and soon realised that the existing pumps had close tolerance impellers and were not designed for large solids or stringy substances like rag.

The solution

Selwood suggested a complete replacement of the existing pumps with its S100 pump, that is designed to take solids up to 75mm. Some S100s had previously been installed at South Eastern depots in Kent and East Sussex so they had already proven their success.

After careful consideration, Southern Rail agreed to full replacements rather than just pump ends to ensure that efficiency was not compromised.

The result

In agreeing a completely new installation, Southern Rail then placed an order for 19 S100 7.5kw electric motored units to be installed at its Brighton, Bognor Regis, Littlehampton, Selhurst and Streatham Hill depots. Selwood was also asked to overhaul two existing S100 units in the Gatwick Express depot at Battersea.

All the units were installed within 15 days in accordance with the contracted time schedule. We were then asked to provide a one year maintenance schedule so that all servicing was carried out to the manufacturers’ warranty guidelines.

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