Every  core barrel manufactured by Polmak Machinery Manufacturing Co. is backed by more than 30 years of our world wide experience in drilling. The problems encountered in going through every type of formation under innumerable conceivable operating conditions have brought about constant improvements in the designs in our present day core barrels. The improvement is continual. We are constantly striving to give our customers the very latest “tried and tested” modifications or improvements as they are developed.

Along with the special type of core barrels presented at soil sampling equipment section , Polmak manufactures DCDMA , Metric and Wireline  series core barrels for various sizes. In the following pages of this section  the principal types of core barrels that are commonly used are shown. In the event that a customer encounters unusual conditions , modifications of existing equipment can be made to meet their specific requirements. POLMAK will be happy to help you in making a selection of the proper type of core barrel to meet your individual needs.

All the core barrels are manufactured from cold drawn seamless steel tubing, which meet or exceed BSI material specifications.

DESCRIPTION

SINGLE TUBE CORE BARRELS

Hard, blocky or compact formations are ideal for the use of single tube core barrels. The single tube core barrels are the cheapest type of core barrels.The simple yet rugged construction allows the driller to use maximum bit pressure thus obtaining a rapid rate of penetration. Single tube core barrels are not recommended for drilling friable or easily eroded formations. When starting a hole directly in rock a short single tube core barrel is used to drill the first four or five meters or until the hole is deep enough to use a longer double tube core barrel. This is necessary since under a normal drilling set up there may not be sufficient space under the chuck to accommodate the longer double tube core barrel.

DOUBLE  TUBE CORE BARRELS

While coring with single tube core barrels circulating fluid is in constant touch with all the cut core. Such continuous contact would cause the disintegration of the core in soft and loosely banded formations. To achieve better core recovery in such friable formations , double tube core barrels were invented where the core is in touch with the circulating fluid only as it is entering the core barrel. As the circulating fluid flows between the inner and the outer tubes , there is no possibility for erosion of the core once it gets into the core barrel.