by making use of hydraulic or pneumatic pressure in a borehole

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Other methods or devices for dislodging with or without loading (breaking-down by means inserted in slits E21C27/14) > by making use of hydraulic or pneumatic pressure in a borehole

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• E21C 37/08 Devices with pistons, plungers, or the like, pressed locally against the wall of the borehole
• E21C 37/10 Devices with expanding elastic casings
• E21C 37/12 by injecting into the borehole a liquid, either initially at high pressure or subsequently subjected to high pressure, e.g. by pulses, by explosive cartridges acting on the liquid (slitting by jets of water E21C25/60; blasting by explosives F42D)
• E21C 37/14 by compressed air; by gas blast; by gasifying liquids