JOSKIN offers 3 main types of hydraulic valves: flat (standard), bell and slide valves. The advantage of the bell type is that its body has a larger diameter, so it is less likely to become clogged with fibres going up in the valve head. The slide valve is the only one that is really sharp: it gets rid of foreign bodies by cutting them. It therefore never gets clogged and is the only one of the three models that is really watertight. However, all three are slurry-tight.