Patent ID: 7445058

Claim:
A nozzle unit for generating an abrasive jet, which nozzle unit comprises: a first nozzle connected to a pressurized carrier fluid supply, which first nozzle in a section thereof with its highest restriction defines a first nozzle opening having a cross sectional area A 1 ; a mixing chamber in which the first nozzle discharges; a second nozzle connected to the mixing chamber, which second nozzle in a section thereof with its highest restriction defines a second nozzle opening having a cross sectional area A 2 ; and an abrasive particle inlet discharging in the mixing chamber; wherein the ratio A 1 /A 2 is greater than or equal to 0.50 and lower than 1, wherein the first nozzle has an inside wall aligned with an inside wall of the mixing chamber and also aligned with an inside wall of the second nozzle.