For extremely thick fluids or solid particles, a specialist valve often known as a knife gate valve is used to cut through the liquid/solids. On opening the gate valve, the flow path is enlarged in a highly nonlinear manner for per cent of opening. This means that the flow rate does not change evenly with stem travel
The special shut-off technique makes it suitable for both fluids and dry media such as pulp, sludge, biomass, powder and different kinds of waste.