University of Finland Study DFS – Dual Fluid Drilling System

Thompson, CT USA

Jyrki Kataja of Tempere University of Technology in Finland recently completed an in-depth analysis of drilled pile execution by dual fluid systems that focuses on Numa’s newly introduced Dual Fluid System. The study details drilling project information including site investigation tactics, pile drilling methods, drilling execution, and supervision and monitoring.

The DFS is a ground-breaking design that combines traditional rotary drilling with DTH drilling. The system consists of a special down hole hammer that uses fluid or slurry to clean the hole instead of air that is commonly used with down hole hammers. Fluid is pumped down a center tube and out the bottom of the drill bit. The pressure of the fluid being pumped down the drill string cleans the bit face and forces all the cuttings up the annulus and outside the casing. This acts to seal off the hole and to prevent any blowouts while drilling. The air that is used to operate the hammer is sent down an air inlet and goes through the hammer to cycle the piston. The air is then exhausted back up through the space located between the hammer and the inside of the casing. Since fluid is continuously pumped during drilling, the DFS has proven to increase penetration rates in clay formations which have traditionally been very difficult to conquer.

The DFS method offers many benefits including the ability to drill perfectly straight holes, faster penetration rates in rock formations, no building damage resulting from vibration, installation of longer drill pipes than with drifters in a confined area, immediate full bearing capacity and immediate grouting is possible. One of the greatest attributes of the Dual Fluid System is its ability to drill through clay and other soft or loose materials. For conventional down hole hammers this is often an impossible or extremely difficult task. The system has been well received in the construction industry because it provides the ability to continuously drill holes in close proximity to each other, which has never been possible with other drilling methods. With Numa’s Dual Fluid Drilling System, holes can be drilled side-by-side because there is virtually no risk of hole collapse and grouting can follow immediately behind to dramatically save time and money.

Mr. Kataja concluded in his study that Numa’s DFS is very reliable and should become widely used in many different applications throughout the drilling industry. He went on to discuss how the DFS is perfectly suited for bridge foundations, railway power poles and wherever top hammers are presently used. During the successful completion of various projects in scope and size, the Numa DFS exhibited the ability to install piles with limited deviation, prevent settlements in embankments and promote faster and more efficient drilling than any other method available.

To obtain a copy of the study, please contact your local Numa representative.

Numa is a major manufacturer of down hole hammers and bits for the international drilling industry. The company designs and builds down hole hammers and bits for drilling vertical and horizontal holes 3-1/2 to 48 inches (89 – 1219 mm) in diameter.

Read more about DFS at: Numa Introduces New Technology: DFS – Dual Fluid Drilling System.

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