Procedure and device for preventing contamination of the nozzles of a spray dampening unit

A spray dampening unit, comprising:

• at least one protective cap surrounding at least one spray nozzle,
• a spray jet aperture in each protective cap, each spray jet aperture structured such that a spray jet produced by the respective spray nozzle is sprayable through the respective spray jet aperture,
• the at least one protective cap overlying and covering the at least one spray nozzle in the direction of a centerline of the spray jet produced by the at least one spray nozzle except for the spray jet aperture,
• the protective cap including an interior space in flow connection with an unpressurized air reservoir, and
• the spray nozzle and the respective spray jet aperture are structured and arranged relative to each other such that a jet pump is formed which discharges and propels air from the unpressurized pure-air reservoir supplied to the interior space, through the spray jet aperture with the spray jet.

A method for preventing contamination of spray nozzles of a spray dampening unit, comprising the steps of:

• separating at least one spray nozzle of a spray dampening unit from surrounding air with a protective cap that overlays and covers the at least one spray nozzle in the direction of a centerline of a spray jet produced by the at least one spray nozzle except for a spray jet aperture thereof;
• supplying an interior space of the protective cap with uncompressed pure air from a pure-air reservoir that contains uncompressed pure air that is separated from surrounding air;
• adapting aperture geometry of a spray jet aperture in the protective cap in relation to a spray jet geometry of a respective spray jet produced by each spray nozzle such that a jet pump is formed and, because of a flow speed of the spray jet, low pressure is produced in the spray jet aperture which results in an additional flow of pure air from the pure-air reservoir to an inside of the protective cap;
• and
• spraying the spray jet through the spray jet aperture in the protective cap such that the jet pump discharges and propels uncompressed pure air from the pure-air reservoir supplied to the interior space, through the spray jet aperture with the spray jet.

A spray dampening unit of a printing press, comprising:

• a spray nozzle;
• a protective cap positioned around the spray nozzle, and having a spray jet aperture, which is structured such that a spray jet produced by the spray nozzle is sprayable through the spray jet aperture, the protective cap overlaying and covering the spray nozzle in the direction of a centerline of the spray jet produced by the spray nozzle except for the spray jet aperture;
• and
• the spray jet aperture having an aperture geometry that is adapted in relation to a geometry of the spray jet such that a jet pump is formed by the protective cap at the spray nozzle through which a flow of unpressurized air is producible in the spray jet aperture when the spray dampening unit is in operation, the unpressurized air flowing from an interior space of the protective cap into a spray chamber outside of the protective cap, such that the jet pump discharges and propels the unpressurized air from the interior space, through the spray jet aperture with the spray jet.

A spray dampening unit, comprising:

• a spray nozzle;
• a protective cap positioned around the spray nozzle, and having a spray jet aperture, which is structured such that a spray jet produced by the spray nozzle is sprayable through the spray jet aperture, the protective cap overlaying and covering the spray nozzle in the direction of a centerline of the spray jet produced by the spray nozzle except for the spray jet aperture;
• and
• the spray jet aperture having an aperture geometry that is adapted in relation to a geometry of the spray jet such that a jet pump is formed by the protective cap at the spray nozzle through which a flow of unpressurized air is producible in the spray jet aperture when the spray dampening unit is in operation, the unpressurized air flowing from an interior space of the protective cap into a spray chamber outside of the protective cap, such that the jet pump discharges and propels the unpressurized air from the interior space, through the spray jet aperture with the spray jet.