SAFETY VALVE Russian patent published in 2006 - IPC E21D23/16 E21D15/51 F16K17/02 

FIELD: mining, particularly slide safety valves adapted to protect interiors of hydraulic prop and hydraulic cylinders in powered roof supports when static loads are applied from enclosing rock side.

SUBSTANCE: valve comprises body having axial borings for filter, washer, seat, piston, thrust, spring, adjusting screw and lock-nut receiving. The washer retains piston sealing pack. The seat is supported by filter body. The piston has blind axial orifice and number of radial orifices and is installed in the axial seat boring. The thrust rests upon piston through ball. Washer is installed between the thrust and the spring. The thrust is provided with channels. The washer and the thrust divide body interior defined by end seat surface and adjusting screw into two chambers, which are communicated with each other by thrust channels. The adjusting screw is provided with axial orifice having area exceeding summary thrust channel throat area.

EFFECT: increased throughput and reduced pressure drop during valve opening or closing.

1 dwg