a positive air system , for a fluid jetting device that jets a fluid in a fluid droplet path prevents the ingress of dust and debris to the fluid jetting device and further prevents the introduction of dust and debris into the fluid droplet path . the air system includes an enclosure having at least one wall defining a barrier and enclosing the fluid jetting device . the barrier defines a local environment . the at least one wall has a plurality of orifices formed therein that are configured to direct a stream of pressurized air therefrom in a direction that diverges from the fluid droplet path . the fluid droplet path and the pressurized air stream direction do not converge so that the pressurized air flowing from the orifices does not interfere with the fluid moving through the droplet path .