Abstract: A valve apparatus for controlling the discharge of material pumped by a material pump through a discharge hose, wherein the valve apparatus includes a substantially sealed flexible bladder in a casing to be located about a discharge hose, and a source of compressed air. Material flow through the discharge hose is prevented by introducing compressed into the flexible bladder, causing the bladder to expand and constrict the discharge hose, and the flow of material is resumed by deflating the bladder. Simultaneous control of the material pump and the valve apparatus is also achieved by the present invention.