Accordingly, the invention provides a spray valve comprising: (a) an upper valve body including a hydraulic chamber for receiving an incompressible hydraulic fluid through a piston port and a piston slidable within said hydraulic chamber; (b) a lower valve body including a fluid conduit for receiving fluid into the spray valve, a lower valve seating surface, an annular fluid chamber around the lower valve seating surface and a fluid outlet; and (c) a seating member between the upper valve body and lower valve body including: (i) an upper seat for the piston within the hydraulic chamber of the upper valve body; (ii) a diaphragm of resilient material extending between the upper valve body and lower valve body; and (iii) a valve seat for bearing against the lower valve seating surface and closing the fluid conduit when pressurised incompressible hydraulic fluid is received through the piston port and displacing the piston within the hydraulic chamber.
