Control Fluid Circuit
In addition to the control fluid circuits used to operate stack functions such as ram or annular preventers, the control system must also perform other functions such as control of subsea regulators, provide readback pressures, latch/unlatch the subsea control pods and charge the subsea accumulators.
Fig 9.4 shows a typical control fluid circuit. The hydraulic fluid is mixed, pressurised and stored in accumulator bottles by the hydraulic power unit. A pilot operated accumulator isolator valve is provided to allow the pumps to charge the subsea accumulators. When control fluid is used, it passes through a totalising flow meter in the hydraulic control manifold and then through the pod selector valve which directs it to the chosen subsea pod.
After passing through the jumper hose and the subsea hose bundle to the control pod, the fluid supplies the hydraulically operated subsea regulators. These reduce the fluids pressure to that required to operate the particular BOP function desired. The fluid is also routed to a SPM valve in the pod which is controlled by the accumulator isolator valve on the hydraulic control manifold. In the open position this SPM valve allows the control fluid to charge the stack mounted accumulator bottles. Shuttle valves allow the bottles to be charged from either pod.
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SECTION 9 : SUBSEA BOP CONTROL SYSTEMS & MARINE RISER SYSTEMS
Figure 9.4 Subsea Bop Control Systems Well Control" href="/well-control/subsea-bop-control-systems.html">SUBSEA CONTROL SYSTEM - HYDRAULIC SCHEMATIC
Figure 9.4 SUBSEA CONTROL SYSTEM - HYDRAULIC SCHEMATIC
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