Tube for the electrostatic coating of workpieces

• US 6,986,366 B2
• Filed: 08/27/2003
• Issued: 01/17/2006
• Est. Priority Date: 08/28/2002
• Status: Expired due to Term

• Current Assignee: Durr Systems Incorporated (Durr AG)
• Original Assignee: Durr Systems Incorporated (Durr AG)
• Inventors: Martin, Herbert, Stiegler, Martin
• Primary Examiner(s): HOOK, JAMES F
• Application Number:
  US10/649,182
• Publication Number:
  US 20050098223A1
• Time in Patent Office: 874 Days
• Field of Search: 138/137, 138/97, 138/98, 138/146, 428/36.91
• US Class Current: 138/98
• CPC Class Codes: B05B 12/14 for supplying a selected one of a plurality of liquids or other fluent materials or several in selected proportions to a spray apparatus, e.g. to a single spray outlet
• CPC Class Codes: B05B 12/1481 comprising pigs, i.e. movable elements sealingly received in supply pipes, for separating different fluids, e.g. liquid coating materials from solvent or air cleaning pipes with pigs B08B9/0557, pigs per se F16L55/26
• CPC Class Codes: B05B 5/1608 the liquid or other fluent material being electrically conductive
• CPC Class Codes: B05B 5/1616 and the arrangement comprising means for insulating a grounded material source from high voltage applied to the material
• CPC Class Codes: F16L 11/12 with arrangements for particular purposes, e.g. specially profiled, with protecting layer, heated, electrically conducting F16L11/11 takes precedence
• CPC Class Codes: Y10T 428/1393 Multilayer [continuous layer]

Abstract

For the pig delivery of the coating material at high voltage in a system for electrostatic mass-production coating of workpieces in the vicinity of grounded parts of the system, a multi-layer tube is provided, whose innermost layer forms the piggable inner wall, while a second layer consists of a high-voltage-resistant isolation material and is surrounded by a protective outer layer.

Claims

1. A tube for the transport of a flowable material, comprising:

a first layer having an inner wall with piggable properties for facilitating the transfer of a pig through said tube thereby moving the flowable material through said tube, wherein said first layer comprises perfluoroalkoxy polymers; and

a second layer providing at least one of isolation material for high-voltage resistance and material providing additional functionality to said tube, wherein said second layer is formed from low-density polyethylene encircling said perfluoroalkoxy polymers of said first layer, wherein said second layer is surrounded by a protective layer positioned adjacent said second layer thereby protecting said second layer from damage, wherein said protective layer comprises perfluoroalkoxy polymers.

2. The tube according to claim 1, wherein said second layer comprises two sub-layers of low-density polyethylene.

3. The tube according to claim 1, wherein said second layer provides electrical resistance of at least about 30 kV/mm.