Q. Reverse and direct circulation drill drilling in piling?

For reverse circulation drilling and direct circulation drilling, major difference in drilling method is connected to the direction of movement of drilling fluid. For direct circulation drilling, drilling fluid is circulated from the drill stem and then flows up annulus between the outside of drill stem and borehole wall. Drilling fluid which carries the drill cuttings flows to the surface and subsequent settlement pits. Pumps are used to lift the cuttings free fluid back to the drill stem. 

For reverse circulation drilling, direction of flow of drilling flow is opposite to that of direct circulation drilling. Drilling fluid flows from the annulus amid the drill stem and hole wall to the drill stem. Drilling fluid is pumped to nearby sump pits where cuttings aredropped and settled.