Aanderaa Recording Current Meter Model 9/11
The RCM 9/11 is a family of single-point Doppler recording current meters with different casing options to allow working at depths of up to 300 (RCM 9 LW), 2000 (RCM 9 IW) or 6000 (RCM 11) metres. The recording unit is 51.3 cm or 59.5 cm high (RCM 9 and RCM 11, respectively) with a diameter of 12.8 cm.
The RCM is most commonly deployed in an in-line mooring configuration. As it operates under a tilt up to 35° from vertical, it has a variety of in-line mooring applications by use of surface buoy or sub surface buoy. The instrument is installed in a mooring frame that allows easy installation and removal of the instrument without disassembly of the mooring line. The instrument can also be used for direct reading of the various parameters. This is conveniently done due to its compact design, low drag force and easy handling. Data can be stored internally and read after retrieval or be read in real time on deck by use of the profiling cable.
Meter comprises:
- A Vane Plate (3681) to stabilise the meter during profiling (stops spin).
- Stainless Steel Mooring Frame made to facilitate easy installation and removal of the instrument by use of two knobs.
- Doppler Current Sensor (Current speed sensor) - Range of speed recorded 0-300 cm s -1 with a 0.3 cm s -1 resolution.
- Hall Effect Compass - Direction recorded with 0.35 ° resolution, 5 ° for 0.15 ° tilt and 7.5 ° for 15-35 ° tilt.
- Thermistor (Temperature sensor) - With selectable wide, low, high and Arctic ranges. Standard range -2.70 to 21.77 °C, accuracy 0.05 °C, resolution 0.1% of selected range, 63% response time (12 sec).
- Inductive Cell Conductivity Sensor (optional) - Range 0 to 75 mS cm -1 , standard resolution 0.002 mS cm -1 .
- Pressure Sensor (optional) - Silicon piezoresistive bridge, standard range 0 to 3500 kPa, resolution 0.1% of range.
- Turbidity Sensor (optional) - Optical back-scatter sensor, resolution 0.1% of full scale, (RCM 11 depth capacity 2000 m).
- Oxygen Sensor (optional) - Oxygen optode, range 0 to 500 µM, resolution < 1µM, response time 60 sec, depth capacity 6000 m.
- Data storage units DSU 2990 and 2990E are standard data storage devices for Aanderaa data collecting instruments.
A built-in quartz clock allows the time of the first measurement to be recorded in the DSU. The measuring system is made up of a self-balancing bridge with sequential measurement of 10 channels and solid state memory. Channel 1 is a fixed reference reading for control purposes and data identification. Channels 2 and 3 represent measurement of current speed and direction. The direction is found by the use of measurements along two orthogonal axis and linking them to true north by use of an internal compass reading. The instrument can operate continuously or in eight intervals from 1 to 120 minutes. At 60-minute recording interval the operating time is more than two years. The current speed and direction are averaged over the measuring interval. Channels 4, 5 and 6 represent temperature, conductivity and pressure respectively.
Further information can be found in the manufacturer's instrument specification .
