Valeport MIDAS - Model WLR -Water Level Recorder and Seabed Tide Gauge

Sensors
The MIDAS WLR comes with a choice of pressure sensor ranges to suit the depth requirement of the operator. The sensor used is a revolutionary piezo-resistive cell with internal temperature compensation, giving the accuracy and resolution levels normally associated with a resonant quartz sensor, but with increased durability, stability and recalibration intervals.

Pressure

• Type: Temperature compensated piezo-resistive cell
• Ranges: 100, 200, 300, 500, 1000, 3000 or 6000 dBar
• Precision: ±0.01%FS
• Resolution: 0.001%FS

Temperature

• Type: Titanium housed PRT
• Range: -5°C to +35°C
• Accuracy: ±0.01°C

Data Acquisition
In line with other Valeport “MIDAS” series instrumentation, the MIDAS WLR samples data points at up to 8Hz, and has a variety of operating modes including continuous data output, triggered sampling, and data bursting. The typical configuration for this instrument is to sample data in a burst mode for a user defined integration period, selectable from a single sample up to 600 seconds. This data burst may then be repeated at a suitable regular interval, from once per minute to once per day.

Sampled data may either be recorded in its entirety, or simply averaged and recorded along with standard deviation data. It is usually recommended that data is averaged over an integration period of 40 seconds to filter the effects of any wave activity.

Note that Valeport’s distributed processing concept allows the pressure data to be automatically converted into the user’s choice of units, including Metres or Feet of water.

Memory
Standard memory is 16Mbyte FLASH, which is capable of storing approximately 2.7 million records. The memory is non-volatile, so data and configuration are retained in the event of power failure.

Communications

• RS232 Up to 200m cable, direct to serial port via USB adaptor
• RS485 Up to 1000m cable, addressable half duplex comms
• Baud Rate: 2400 - 115200 (FSK fixed at 19200, USB 460800)
• Protocol: 8 data bits, 1 stop bit, No parity, No flow control   

Electrical

• Internal: 8 x C cells, 1.5v alkaline or 3.6v lithium
• External: 9 - 30vDC
• Power: 0.3W (sampling), <1mW (sleeping)
• Battery Life: 90 days operation (alkaline) or 215 days (lithium) based on a 40 second burst sample every 10 minutes
• Connector: Subconn MCBH10F

Software
System is supplied with DataLog Express Windows based PC software, for instrument setup, data extraction and display. DataLog Express is license free.

Physical

• Instrument: 88mmØ x 550mm, 7kg (acetal), 11kg (titanium)
• Cage: 750mm x 140mm x 120mm
• Depth Rating: 500m (acetal), 6000m (titanium), Sensor range permitting.
• Shipping: 100 x 18 x 49cm, 20kg (acetal), 24kg (titanium)