Waterway Configurations for Surface-Set Core Bits
With the exception of some thin-kerf surface-set core bits, most sizes are offered in three different waterway configurations. These various waterway configurations have distinct ranges of application and have the function of controlling the bit hydraulics.
Regular Configuration (Style ‘W’)
Unless otherwise specified, this is the standard waterway configuration used on all mineral exploration of surface-set core bits manufactured by Dimatec. This design uses canal type waterways that are approximately 0.12 inch (3 mm) wide. These waterway canals pass the circulating fluid from inside diameter of the bit crown, across the face and eject the fluid and cuttings at the outside diameter of the bit crown.
The Style ‘W’ waterway configuration is available for all sizes of surface-set diamond core bits produced by Dimatec.
The Dimatec code for this waterway configuration style is ‘W’. (Example: A Dimatec core bit with the descriptor ‘6W’ in its designation would indicate that the bit is supplied with 6 internal discharge canal type waterways).
Other customer specified waterway canal widths are available on request. In addition to the rectangular shaped waterway canals shown above, thick-kerf, large diameter surface-set diamond core bits are often supplied with trapezoidal waterway canals to aid in the ejection of cuttings from the bit face.
Face-Discharge Configuration (Style ‘FD’)
This waterway configuration is recommended for use when drilling in relatively soft, unconsolidated formations and/or when using triple-tube wireline core barrel systems. Unlike core bits that are manufactured with conventional canal type waterways that eject the circulating fluid through ports on the inside diameter of the bit crown, the Face-Discharge (Style ‘FD’) configuration ejects the fluid through ports moulded into the face of the bit. The re-direction of the circulating fluid results in minimum core wash and reduces the potential for subsequent core erosion.
In most cases, waterway element typically has a canal width and flushing port diameter of 0.25 inch (6.3 mm).
The Style ‘FD’ waterway configuration is available on all wireline core bits as well as on core bits with kerf widths greater than 0.39 inch (10 mm) that are used with conventional (non-wireline) core barrel systems.
The Dimatec code for this waterway configuration style is ‘FD’. (Example: A Dimatec core bit with the descriptor ‘6FD’ in its designation would indicate that the bit is supplied with 6 face-discharge type waterways).
Slot Face-Discharge Configuration (Style ‘SFD’)
This waterway configuration is a modification of the Face-Discharge (Style ‘FD’) waterway configuration and has the same basic range of application. This style of core bit is manufactured with wide waterway canals that include slot shaped face-discharge ports. This configuration is recommended for use where:
- The bit cuttings are large and high flushing volumes are required to clear them.
- The standard cylindrical shaped face-discharge ports (Style ‘FD’) become easily blocked by silt.
- High viscosity circulating fluids such as foam are in use.
- Compressed air is used as the flushing media.
The Slot Face-Discharge (Style ‘SFD’) waterway configuration is only available on core bits with outside set diameters of 2.95 inch (75 mm) or greater and with kerf widths of 0.50 inch (12.7 mm) or greater.
The Style ‘SFD’ waterway configuration develops fluid pressures across the bit face that are even lower than that of the similar Style ‘FD’ configuration. This results in minimal bit face fluid turbulence during operation.
The Dimatec code for this waterway configuration style is ‘SFD’. (Example: A Dimatec core bit with the descriptor ‘5SFD’ in its designation would indicate that the bit is supplied with 5 slot face-discharge type waterways).