Apparatus and method for coating substrates with washcoats

A substrate coating apparatus comprising:

• a source of a washcoat;
• a washcoat showerhead for discharging the washcoat towards an upper surface of a substrate;
• a headset for engaging the substrate to locate the upper surface of the substrate below the washcoat showerhead;
• and
• a vacuum generator for drawing the washcoat discharged from the washcoat showerhead through the substrate;
• the substrate coating apparatus further comprising a valve assembly for controlling flow of washcoat into the washcoat showerhead, the valve assembly comprising:
• an inlet for receiving the washcoat supplied from the source of washcoat;
• an outlet for supplying the washcoat to the showerhead;
• and
• an outlet valve movable between a closed state and an open state to control flow of washcoat out of the outlet;
• wherein the valve assembly is configured to create a pressure drop within an interior of the washcoat showerhead when the outlet valve moves from its open state to its closed state.

A valve assembly for a substrate coating apparatus comprising:

• a valve chamber;
• an inlet for receiving washcoat;
• an outlet for supplying the washcoat to a showerhead;
• and
• an outlet valve movable between a closed state and an open state to control flow of washcoat out of the outlet;
• wherein the valve assembly is configured to create a pressure drop within the valve chamber when the outlet valve moves from its open state to its closed state.