Discoveries during Development of the next generation Ultrahigh Pressure Water Jetting Machines
Author : Tron-Halvard Fladby, M.Sc. Mech. Eng.
Managing Director, Speeder AS
In todays society we often take it for granted that the technique have come so far in development that there are only room for marginal improvements within 2-10 %. You will therefore, I expect, also be quite surprized when you see what can be discovered even within relatively common technique where so may have worked with in years. That we have found new improvements that can contribute to a increase in efficiency of fabulous 300 til 500 %. Yes, you read right. This incredible but still true perspective one should perhaps also keep an open mind for elsewhere.
The incredible importance of the water jet motion pattern
In connection with development of Speeders new compact ultrahigh water jetting machine we made two epoch-making discoveries. In order to make optimum lances and nozzles we made close studies of the jet movements. It may immediately seem a little unnecessary to evaluate this more closely because it is easy to take for granted that some of all the others that have worked with ultrahigh pressure water jetting had analysed this carefully to get the outmost out of the equipment. But it is impossible that anyone of them can have done so when you see what we have discovered. The discoveries are very important because all the equipment in use when water jetting have only one purpose; To see that the water jet hits the surface just at the spot where you want it, with sufficient power and quite correct angle all the time. Then maybe it isn't so unnecessary to study it thoroughly after all. It is the only thing that matters. When ultrahigh pressure cleaning we must use nozzles with motion because the jet is like a sharp awl and if we should use a motionless nozzle, it would be like colouring a piece of paper with a ball-point pen. It would be difficult and work demanding to get an adequate and even surface treatment. Until now the normal solution has been to use a rotating nozzle. That is a nozzle placed with an angle in the front of a pipe that rotates by means of a motor, normally hydraulic or air driven. With this nozzle the jet gets a track that can be described as a hollow cone that hits the surface in a circle. By moving the lance, the jet covers an area that corresponds to the diameter of the circle. Speeder AS has developed a new linear solution, where the nozzle is moving back and forth by means of a little air driven linear motor that pushes directly on the nozzle. A very simple, efficient, reliable and reasonable priced solution. You will get a quite efficient treatment right from the start of the working area. It will be easy to limit the field you want to clean from rust to where there actually is rust. Furthermore you can incline the jet with a certain optimised angle on the surface and in that way strip the surface much more efficiently from rust and old coating. The Speedclean jet works in the most efficient way with rust removal absolutely all the time because it "skips" the wasted time and energy that will be thrown away when the jet passes the circle side in the circle and return over the cleaned area in the back of the circle. The drawing 1 in this article shows the difference between using a Speedclean linear moving nozzle and all other types of normal rotating nozzles in use today in a very revealing way. Notice that the thickness of the illustrated jets are shown equal for both nozzles.
The motion pattern with the new Speedclean nozzle with linear motion compared with rotating nozzle. As you can see the figure shows that it is 3.14 times more efficient to move the jet linear in stead of in circular movements because the jet then always works on new areas and not over and over again along the circle sides and returning over finish cleaned area.
Over 3 times more effective
From the illustration in this article you can see that a ultrahigh pressure cleaner with 3 litre per minute capacity and Speeder linear nozzle solution has a working capacity equivalent to all the others with more than 9 l/min and rotating nozzle. Because of the possibility of using the right angle all the time on the jet in under rust and old paint, the enormous speed pressure in the water will peel of or shatter away everything that shall be removed in a very efficient way. The efficiency will thus be increased several times by using Speeders nozzle with linear motion in stead of circular motion.
Rotation destroys the water jet
By the way, have you ever noticed that rotating jets always seems to be foggy? There is of course a very natural explanation for this. When the water moves towards the nozzle opening inside the rotating tube it rotates with the same number of revolutions as the nozzle but at a much larger diameter. When the water is forced in to the opening itself as you can see in drawing number 2, the rotation speed of the water will increase many times compared to the original speed.
This shows how the water jet with Speedclean linear nozzle without rotation keeps gathered and thus gives full force for cleansing the surface. With rotating nozzle the water jet will be blown apart of the centrifugal force due to the rotation and the rotation acceleration through the nozzle orifice when the water leaves the nozzle.
For instance, if the number of revolutions on the nozzle for instance is 1000 revolutions per minute, the rotation speed in the smallest opening can reach as high as 5000. Because of this rotation in the water jet the centrifugal forces will burst the jet and the droplets in it will be blown apart immediately after the jet has left the nozzle. The water doesn't continue as a solid massive jet until it hits the surface and unnecessary much of the effect in the jet will get lost. You will not have these problems with a nozzle with linear movement, because the water in this solution will not be put into rotation.
An ultrahigh pressure cleaner with linear stripping nozzle therefore replaces a much larger machine with rotating nozzle. All rust, water, old paint and gush flies in addition to a direction that you can decide yourself, away from the operator. The covering can thus be limited and the working environment for the operator will be much better. You can start quite at the edge without getting the splash on the wrong side and you can work quite into a corner without that the jet needs to touch another material. That can of course be a material that can't stand the ultrahigh pressure water jet. The recoiling will be reduced to 1/3 or equal to that of an efficient normal high-pressure cleaner. It will thus be much better to work with. In addition we achieve that the lance has lower weight and is easier to keep and of course produce less noise. All together this means a lot for the operator who shall work efficient with this equipment over time. And last but not least, the most important as always; the work can be done better, faster, with less effort, power and resource consumption and to a fraction of the investment cost and a much lower operating cost.
Can be used for cutting steel
By maintenance, removing of cracks in steel and rebuildings etc. you must often have the possibility to cut in steel plates and other metals. Many times you have to do this without heat because of fire or explosion hazard. It may also be of great importance not to get changes in the steel structure because it can weaken the material. Therefore ultrahigh pressure water with added garnet abrasives in the water jet will be the best solution. The so called abrasive watercutting. Because Speedclean ultrahigh pressure cleaners have the same capacities as professionell water cutting machines, we will develop additional equipment for abrasive water cutting i.e nozzles, feeders and containers for cutting of everything from steel to concrete. Thus, people who need fire- and explosion proof equipment which can be used everywhere in all directions without doing any harm to the material can get what they need.
It will revolutionize the spreading of water jetting
We therefore think that this will revolutionize the spreading and the use of ultrahigh pressure cleaning. Other techniques like sand blasting are already before this in full retreat compared with water jetting. When the efficiency increases with more than 3-5 times compared with others, the investment costs are reduced to a fraction and the running costs are heavily reduced, the use of ultrahigh pressure cleaning will really take off and oust out other old techniques. It may be needless to write, but Speeder has of course patented their linear solution.
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Revised: Thursday, 08-Oct-2015 11:52:17 AEDT