Reverse Circulation
The Colcrete Eurodrill Reverse Circulation (RC) Drilling System has been designed to operate with DTH hammers, standard hammers with cross-over substitution and skirted RC rock bit assemblies as detailed below.
Upper swivel
Required where rotating power swivel contacts to the stationary return hose.
Lower side inlet swivel
Located below power swivel, allows air circulation to drill rod whilst allowing return cuttings to pass through swivel to upper swivel and return hose.
Saver substitute
Reduces wear on side inlet swivel threading, inner cross-over
also provided with substitute.
Drill rod
Double tube drill rod provided with inner tube and friction
welded and nitrided tool joints. Screwing rods together
automatically seals the inner tube without the need to provide further connection parts.
Cross-over substitute
Allows any standard hammer to be used, the transfer of cuttings to the inner return tube taking place through the cross-over substitute, screwed to standard DTH hammer.
Reverse circulation DTH hammer
It is necessary to have a cross-over substitute connecting RC drill rods to back connection on hammer. All RC DTH hammers can be accommodated to this system.
Skirted rock bit assembly
Assembly can be connected directly to RC drill rod. Operating as a standard
| Outside Diameter Outer Rod (mm) | Inside Diameter Inner Rod (mm) | Thread Type |
|---|---|---|
| 88.9 | 38.1 | Euro 90 |
| 95.3 | 38.1 | Euro 95 |
| 101.6 | 38.1 | Euro 100 |
| 114.3 | 50.8 | Euro 114 |
| 139.7 | 88.9 | Euro 140 |
| 168.3 | 101.6 | Euro 168 |
| Outside Diameter Outer Rod (in) | Inside Diameter Inner Rod (in) | Thread Type |
|---|---|---|
| 3.5 | 1.5 | Euro 90 |
| 3.75 | 1.5 | Euro 95 |
| 4 | 1.5 | Euro 100 |
| 4.5 | 2 | Euro 114 |
| 5.5 | 3.5 | Euro 140 |
| 6.63 | 4 | Euro 168 |
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