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Solenoid valves used in trains

Danfoss valves keep Czech train toilets flushing despite the cold

28 June 2010
In autumn 2004, České Dráhy (Czech Railways) signed a contract with fellow Czech company, Pars Nova, for the supply of 130 railcars. Operating on regional routes, the railcars have a preassembled vacuum toilet module, with a built-in pressurised water system – and Danfoss solenoid valves were chosen to control the water system. Designed specifically for use in closed circuits with low differential pressure, the EV250B empties the railcars’ water tanks and makes sure the toilets will keep flushing for years to come, even in freezing conditions.

Protection from drops in pressure and temperature

Each toilet module has a self-supporting framework, with a built-in, electronically-controlled water supply system. And three Danfoss EV250B solenoid valves help control the water in the system. Selected for their quality, reliability and durability, the valves keep the system working during rail journeys. But, just as importantly, they also help empty the system of water 30 minutes after the carriages have completed their journey.

A vacuum toilet relies on pressure to control flushing and water flow in the pipe system. If the pressure drops below 450 kPa, a solenoid valve stops the water flowing into the toilet – and the control unit drains the water to prevent frost damage to the system when the train is not in use.

It can get very cold in the Czech Republic during winter, with temperatures in some areas falling as low as -17°C. To prevent the water system freezing when the railcars are at the depot, the toilets have a safety thermostat in the drain pipe.
Solenoid valve EV250B
If the temperature falls below 5°C, it sends a signal to the second solenoid valve. The valve then drains the tank and pipe system through an overflow pipe, to prevent the water freezing and destroying the pipes.

To help passengers stay fresh and clean, a third solenoid valve controls the flow of hot water from the boiler to the hand basin at the push of a button. Again, if the water temperature in the boiler circuit falls below 5°C, the solenoid valve drains the water from the system.

Czech Railways are very pleased with the new vacuum toilets and has signed a contract for a further 70 railcars to be delivered, complete with vacuum toilets, between 2010 and 2014. If you’d like to learn how Danfoss can help you, please contact your nearest Danfoss dealer.


By Pavel Pecina, Sales Engineer
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