DS EN 12050-4:2001 Wastewater Lifting Plants For Buildings And Sites - Principles Of Construction And Testing - Part 4: Non-Return Valves For Faecal-Free Wastewater And Wastewater Containing Faecal Matter Defines general requirements, basic construction and testing principles together with information on materials and conformity evaluation. Pertains to non-return valves used in conjunction with faecal