(19)
(11) EP 0 325 021 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.03.1990 Bulletin 1990/12

(43) Date of publication A2:
26.07.1989 Bulletin 1989/30

(21) Application number: 88307801.6

(22) Date of filing: 23.08.1988
(51) International Patent Classification (IPC)4: B41F 7/24
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 12.01.1988 US 142993

(71) Applicant: BALDWIN TECHNOLOGY CORPORATION
Stamford Connecticut 06902 (US)

(72) Inventor:
  • MacDonald, Robert W.
    Ridgefield Connecticut 06877 (US)

(74) Representative: Warren, Anthony Robert et al
BARON & WARREN, 18 South End, Kensington
London W8 5BU
London W8 5BU (GB)


(56) References cited: : 
   
       


    (54) Circulation system and method for reducing foaming in the dampening system of a printing press


    (57) A circulation system for reducing foaming of the water or water and isopropanol wetting fluid circu­lating in a printing press, comprises a fountain pan (20) which drains into a vented return conduit (26). The vent exhausts air drawn into the circulation system to minimize foaming. A sump (36) is provided at a low point in the circulation system to prevent air entrainment in the system during start up. Wetting fluid is drawn from the sump (36) by a venturi tube (38) calibrated to provide a sufficient amount of suction that will drain the sump (36) but which will not draw air into the circulation system from the fountain pan (20). The venturi tube (38) has at least one, and preferably two orifices (52, 54) therein. The circulation system allows increased wetting fluid flow rates while reducing foaming, reducing the tempera­ture increase across the fountain pan inlet and outlet by one-half of that of prior art devices.







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