Dissolved gas flotation pressure reduction nozzle

1. A dissolved gas flotation pressure reduction nozzle ( 60 ) comprising:

an integrally moulded plastics component ( 61 ) comprising a discharge spout ( 62 ), an impingement plate ( 64 ) and one or more fins ( 66 ) extending from the impingement plate ( 64 ) in the radially outwards and downstream directions; and

a control plate ( 75 ) upstream of the impingement plate ( 64 ).

2. A nozzle ( 60 ) as claimed in claim 1 , wherein at least one fin ( 66 ) or a part ( 190 ) thereof lying radially outwards of the impingement plate ( 64 ) has non-parallel faces ( 70 , 74 ; 170 , 174 ) diverging in the upstream to downstream direction.

3. A nozzle ( 60 ) as claimed in claim 1 , wherein at least one fin ( 66 ) or a part ( 190 ) thereof lying radially outwards of the impingement plate ( 64 ) has one face ( 70 ) substantially parallel to the discharge spout axis ( 72 ) and one face ( 74 ) at an angle of 0.5° to 90° to the discharge spout axis ( 72 ), or has two faces ( 170 , 174 ) each at an angle of 0.5° to 90° to the discharge spout axis ( 72 ).

4. A nozzle ( 60 ) as claimed in claim 1 , further comprising a baffle ( 180 ) downstream of the one or more fins ( 166 ).

5. A nozzle ( 6 ) as claimed in claim 4 , wherein the baffle ( 180 ) has non-parallel faces ( 182 , 184 ) converging in the upstream to downstream direction.

6. A nozzle ( 60 ) as claimed in claim 1 , wherein the integrally moulded plastics component ( 61 ) further comprises a connector portion ( 63 ) for connection to a socket.

7. A nozzle ( 60 ) as claimed in claim 1 , wherein the discharge spout ( 62 ) comprises grips ( 65 ).

8. A nozzle ( 60 ) as claimed in claim 1 , wherein the plastics is acrylonitrile butadiene styrene (ABS).

9. A nozzle ( 60 ) as claimed in claim 1 , wherein the control plate ( 64 ) is formed of stainless steel or of plastics.

10. An assembly comprising a nozzle ( 60 ) as claimed in claim 1 and a socket.

11. A dissolved gas flotation apparatus comprising at least one assembly as claimed in claim 10 .

12. A dissolved gas flotation apparatus as claimed in claim 11 , wherein at least one nozzle ( 60 ) is arranged such that the axis of the discharge spout is within 15° of vertical.

13. A method of manufacturing a nozzle ( 60 ) as claimed in claim 1 , wherein the integrally moulded plastics component ( 61 ) is moulded using two internal tooling elements which operate together to form the impingement plate ( 64 ) and to form the fins ( 66 ).

14. A method as claimed in claim 13 , wherein the control plate ( 75 ) is placed in position after moulding and before cooling of the integrally moulded plastics component ( 61 ) and is held in place by the plastics component ( 61 ) after cooling.

15. A dissolved gas flotation process using an apparatus as claimed in claim 11 .

16. A dissolved gas flotation process as claimed in claim 15 , wherein the process is carried out on salt water.

17. A salt water desalination process comprising an initial dissolved gas flotation process as claimed in claim 16 .