The Feritech piston corer combines operational safety with survey efficiency and reliability it is a standard and very popular tool within marine survey. The improved recovery and less disturbed sediment sample yields a higher quality result compared to that of a standard gravity corer. The piston reduces internal friction between the sediment and the liner, this helps to prevent samples plugging the liner and reducing the sample return.
The FT510 standard piston corer pack and the FT511 automatic drop piston corer pack upgrade our FT520 gravity corer to operate as a piston corer.
Both Feritech piston corer triggers have a long proven safety record with features including our unique hydrostatic safety arming mechanism that activates the trigger at a preset depth keeping the user safe and guarding against accidental triggering during deployment.
The FT511 automatic drop trigger system has been developed to aid recovery.
Once the trigger weight or small gravity corer on the messenger wire touches the seabed and releases the piston corer from the trigger mechanism, it slackens its grip and drops down to the end of lift wire. This simplifies recovery as there is no gap between the trigger and the corer.
Hydrostatic safety arming mechanism (HSAM)
Feritech has developed a hydrostatic safety arming mechanism which is installed on all our piston and jumbo piston corers. This addition makes the piston corer safer.
The user sets the HSAM to arm the trigger at the required depth. In water less than the specified depth the trigger mechanism is deactivated meaning that if it gets knocked during deployment it will remain safe and not release the corer prematurely.
Launch and recovery system
The piston corer has an optional, over-the-side, launch and recovery system (LARS). This greatly improves deployment and recovery efficiency, it also makes the changing of barrels much simpler and safer.
The LARS improves safety for the engineers working with the equipment ensuring the corer is securely held on deck and can be handled securely.
How does a piston corer work?
Both piston coring and jumbo piston coring work in much the same way. A jumbo piston corer has a wider diameter barrel and can be as much as 30m long where as a standard piston corer is typically up to 9m long. The trigger mechanism is based around the Kullenberg design.
On the way down through the water column the Feritech hydrostatic safety release arms at the set depth, this allows the piston corer to release when it reaches the sea floor.
The piston corer is released when a weight (or small gravity corer) on the end of a messenger wire touches the seabed and allows the tripping arm to open.
Once released the main piston corer free falls into the sea floor under its own mass (anywhere between 200kg to 1000kg for our standard piston corer and 500kg to 4000kg for the jumbo piston corer)
As the piston corer penetrate the seafloor, the piston inside stops at the sea floor. As the corer penetrates the action of the piston creates a pressure differential at the top of the sediment column that encourages marine soil to enter the core liner in an undisturbed state.
At the same time the Feritech trigger arm and mechanism slackens its hold on the lifting wire and drops down to be on top of the corer once again ready for simple recovery.
After a few seconds the coring process is complete and the system is recovered back on to the vessel so that the core can be processed.