Pressure Compensated vs Load Sensing Pumps

A non-compensated flow control simply restricts flow without accounting for pressure variations, meaning actual flow changes as system pressure fluctuates. A compensated flow control maintains consistent flow regardless of upstream or downstream pressure changes by using a pressure-reducing element. For subsea actuators, oil compensation specifically maintains a fixed positive pressure differential over ambient seawater pressure.

A load sensing pump continuously monitors the pressure demand at the actuator and adjusts its output to deliver only the pressure and flow required by the load — plus a small margin. This reduces energy waste and heat generation. In contrast, pressure-compensated systems like NV Mechanics Design's underwater actuators maintain a set internal oil pressure to counteract external hydrostatic pressure at depth.

NV Mechanics Design Ltd. offers actuators rated to 3,000 msw (meters of sea water) for the self-compensated linear and rotary models, and up to 6,000m depth for the heavy-duty linear actuator series. The 260cc Oil Compensator accessory is also rated to 6,000m, supporting a wide range of subsea deployment scenarios.

The 260cc Oil Compensator maintains a positive internal pressure of 0.7 to 1 bar above ambient seawater pressure using a rolling diaphragm and SST or Inconel spring. This differential ensures that if any seal imperfection exists, oil exits rather than seawater enters — protecting internal electronics and mechanical components from corrosive marine water.

Both the linear and rotary self-compensated actuators support RS422 (RS485 full duplex on 4 wires) and RS232 serial communication at 19200 baud. All configurable parameters — including status broadcast frequency, virtual limit switch positions, and encoder settings — are stored in internal EEPROM, enabling standalone deployment without an external controller.

Yes. The self-compensated linear and rotary actuators from NV Mechanics Design Ltd. use a 30-bit absolute encoder (14-bit single-turn resolution plus a 16-bit turns counter) mounted directly on the output shaft. Position data is retained in the encoder between power cycles, allowing the actuator to resume from its last known position without re-homing after restoration of power.