A company working on state of the art technologies in the rail sector have developed a new prototype that provides on-board toilet waste recycling.

Providing highly specialised rail depot equipment, the original equipment manufacturer were looking for a suitable valve for train toilet waste to install onto their prototype to direct the liquid flow in the filtration process, through the correct systems. The valves were going to be installed onto rolling stock, and the company were working with a University to develop the product.

The OEM were committed to test the first prototype on a rail vehicle, and then build three further prototypes over the next 12 months for testing.

Due to limited space, weight constraints, and needing a minimum maintenance, non-fouling valve solution, the company opted for Pinch Valves from AKO UK which ticked all of the above boxes. They needed 2 normally closed valves and 2 normally open – 4 valves in total per prototype, plus some spares. They wanted to use sanitary hygienic stainless steel pipe work for the liquids sub-system where the valves would be used with tri-clamp fittings.

valve for train toilet waste

Black Water Application

The toilet waste liquid that is controlled by the Pinch Valves is classed as black water that has been filtered to remove all solids. The black water could have cleaning products in it, as well as fecal solids and paper up to 2mm in size.

The liquid flow rate of the application was less than 5.0lpm at a flow pressure of 3 BAR max. When closed, the valves for train toilet waste were required to prevent flow with a pressure of 6 BAR in the liquid line.

Pinch Valve used within this application – VMC10.04HTECK.50T.50, also DN15, DN20 & DN25

VMC model, air operated, stainless steel body, stainless steel tri-clamp ends, EPDM rubber sleeve.

Valves for Train Toilet Waste: Operating the Valves Correctly

The human waste liquid passing through the Pinch Valves is 10 to 20 degrees Celcius, and is being conveyed at a pressure of between 0.1 – 3 BAR

The VMC Pinch Valves for train toilet waste offered by AKO UK are all rated to 6 BAR line pressure and require 2 BAR above the line pressure to 100% close. (For example, if a process line pressure is 4 BAR then you would need 6 BAR to close). AKO UK recommended to keep to the 2 BAR as a maximum, since over pressuring the Sleeves can cause Sleeve deformities. Using the correct control pressure for the valves is important.
In this application, the Pinch Valves direct the liquid flow in the filtration process, through to the correct systems.
valve for train toilet waste recycling
valve for train toilet waste recycling

Customer Feedback & Market Potential

The OEM have successfully trialed Pinch Valves for train toilet waste from AKO UK and have since placed further orders for further manufacturing. They have currently been using Pinch Valves within their builds for one year, and consider the AKO Pinch Valve to be the best design of valve to prevent fouling. They are satisfied with the valve as a product, and have not yet needed to replace any of the rubber sleeves, which are the only wearable part.

From the reaction of the railway market thus far, the OEM are expecting to get annual sales of circa 1000 units over the next 3 to 5 years. Spare parts will also be ordered when required.

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