The application of waterjets for cleaning
Abstract
The last 25 years has seen a dramatic growth in the use of high pressure waterjets for cleaning purposes. Throughout recorded history and no doubt for a long time before that, the dual role of water as both a solvent and a lubricant has been one of the major ways of washing surfaces down regardless of what the surface was. Also, the power built into a waterjet stream has allowed it to be used in moving material. In ancient Egypt rivers were commonly diverted to erode valuable mineral deposits and it was not until 1852 that the modern innovation of hydraulic mining got its start in the hills around Sacramento. The power of the waterjets used in those mining operations were such that most of the gold in California and later in Idaho and many of the other western states was mined hydraulically. Subsequently, the technology has advanced considerably by the use of increasingly high pressures and smaller jets to the point where today abrasive laden waterjets at pressures above 35,000 psi are becoming the tool of choice for cutting glass, titanium, and composite materials. Applications of high pressure waterjets to cutting are usually however, governed by a different set of requirements to those of the cleaning operation. Specifically, while in a cutting or mining operation one is seeking to remove the most volume of material with the least amount of energy looking for deep cuts and applying a highly focused jet energy to the surface. Frequent cleaning requires the ability to remove only one or two surface coatings which may be very shallow. It is generally important that the underlying material or substrate is not damaged by the cleaning process, and thus, the energy of the jet must often be more diffuse. In contrast also with conventional cutting where the depth of the cut has great importance in cleaning it is the area which can be covered in a given time which better optimizes the process. An example of the types of requirement needed can be illustrated by the failure of paint. Where an overcoat of paint fails, that layer must be removed from the surface before a fresh protective coating can be applied. By the early 1980's the cost of this operation in the UK alone exceeded 600 million dollars.
- Publication:
-
Environmentally Benign Cleaning and Degreasing Technology: JANNAF Safety and Protection Subcommittee and Propellant Development and Characterization Subcommittee Joint Workshop
- Pub Date:
- June 1994
- Bibcode:
- 1994ebcd.work..269S
- Keywords:
-
- Cleaning;
- Cutting;
- High Pressure;
- Hydraulic Jets;
- Jet Control;
- Jet Flow;
- Nozzle Design;
- Solvents;
- Technology Assessment;
- Washing;
- Water Treatment;
- Abrasives;
- Cost Analysis;
- Depth Measurement;
- Failure Analysis;
- Lubricants;
- Operating Costs;
- Paints;
- Protective Coatings;
- Substrates;
- Fluid Mechanics and Heat Transfer