ISO 20662:2020 Ships and marine technology — Hopper dredger supervisory and control systems.
e) Jet water system: the jet water system should involve the monitoring and control of the jet pump, hopper jet water valve, and draghead jet water valve. The jet water system includes the jet water pressure, jet water flow, jet PUMP speed, jet pump power, hopper jet water valve state, and draghead jet water valve state sensors.
f) Dredge valve system: dredge valve system construction of mixture channel for dredging operation. It should involve the monitoring and control of the dredge valve.
The HD-SCS should adopt a multi-layer network structure, including equipment layer, process
monitoring layer, and information management layer, as follows:
a) equ iprnent layer: field instrumentation/sensors;
b) process monitoring layer: PLC, signals collecting and processing units, communication network;
c) information management layer: central monitoring and control station.
5 General requirements
5.1 Operating position and control mode
5.1.1 Operating position
The I-ID-SCS should have local and remote operating positions.
5.1.2 Control mode
The l-ID-SCS should have the following control modes:
a) manual: manual operation by handle/button/knob and in graphical user interface;
b) emergency: direct operation through hardwire, only for dredging equipment that affects the safety of the ship.
5.2 External communication
The I-f D-SCS should have communication with a tide-system.
When the equipment start and stop control, operation position transfer, or control mode shift operation fails, the I-f D-SCS can provide diagnostic information to accommodate a safe dredging.
The STPM/STWC should have the following functions for the equipment operation:
a) hoisting/lowering of the trailing suction tube(s);
b) controlling of gantries;
c) adjusting of the visor angle;
d) stroke and pressure regulation of the swell compensator.
The STPM should display the following information:
a) top view, side view, and back view of the suction tube with relation to the dredgers position;
b) depth of draghead, and horizontal distance between draghead and hull;
c) status of the suction tube in seated position;
d) stroke of swell compensator;
e) position of the gantry.
The STPM should give the alarm under the following circumstances:
a) the draghead position is below the maximum depth setpoint;
b) the suction tube is too close to the hull;
c) the suction tube is too close under the ship;
d) the suction tube is at the highest or lowest position;
e) the pivot vertical and horizontal angles are greater than the pre-set values.
The depth of the draghead can be calibrated in the STPM.ISO 20662 pdf download.