boss 50 connected to cover 43 and in which is also provided a seal 51 for sealing the gap between supply pipe 41 and a bore 52 in boss 50 a not shown sealing means is also provided between cover connection 45 and cover 43 on its bottom the air container 40 has mounted to it an output guide section with a conical portion 53 which passes into a cylindrical guide portion 54 having a smaller diameter than air container 40 at the free end of guide portion 54 is provided an inwardly projecting shoulder 56 while on the outer periphery of the output is arranged a mounting flange 57 with which feed unit 12 on cover 2 e g on its top 8 is fixed to a mounting flange 35 by means of screws and suitable sealing means if feed unit 12 with guide connection 54 is fitted into cover 2 mounting flanges 36 37 can be provided for this purpose at the transition between air container 40 and conical connection 53 in this case the fluid stream in conduit 14 also flows round the lower part of feed unit 12 comprising connections 53 54 an output restricting nozzle 60 which passes into an outlet connection 61 is supported on shoulder 56 the output nozzle 60 has radially directed webs 62 carrying a boss 63 in whose bore 64 supply pipe 41 with spraying nozzle 42 is secured by means of a setscrew 65 above boss 63 supply pipe 41 carries a further boss 68 provided with a setscrew 67 and to which is fixed a vortex member or body 70 the vortex body.