The OBS-3A combines our OBS probe with pressure, temperature, and conductivity sensors in a battery-powered recording instrument. The monitor is operated with software running under Windows 98, 2000, and XP.

Features

• No cable required, runs 1,500-8,000 hours on 3 D-cells
  
• Measures sediment concentrations to 5,000 mg/ι & turbidity to 4,000 NTU with field-proven OBS technology (U.S. Patent No. 4,841,157)
  
• Logs depth, wave height, wave period, temperature, and salinity
  
• Records 200,000 lines of data in FLASH
  
• Compact package - 76 mm (3') by 362 mm (14.3')
  
• Program setpoints & sampling times

Applications

• Record turbidity at remote sites
  
• Monitor dredging & mining operations
  
• Wastewater effluent measurements
  
• Control water clarity in settling ponds
  
• Sediment transport research
  
• River and stream gauging
  
• Permit compliance

Specifications

• Ranges
  
  • Turbidity: 0-4,000 NTU
    
  • Concentration: Mud -5,000 mg/l; Sand 0-50 g/l (depends on sediment type)
    
  • Pressure: 0-200 dBar (200 m)
    
  • Temperature: 0-40° C
    
  • Conductivity: 0-65 mS/cm

• Accuracy
  
  • Turbidity: 0.5 NTU or 1% of reading 2
    
  • Concentration: Mud 1.0 mg/l or 1% of reading; Sand 0.5 g/l or 1% of reading (whichever is larger)
    
  • Pressure: 0.2% of f.s. (f.s. = 50, 100 or 200 dBar)
    
  • Temperature: 0.05° C
    
  • Conductivity: 0.1 mS/cm

• Other Data
  
  • PC interfaces: RS-232 / 115 kbps; RS-485 / 115 kbps; USB
    
  • Maximum data rate: 2 Hz
    
  • Infrared wavelength: 875 nm
    
  • Maximum depth: 300 m
    
  • Drift: < 2% / year
    
  • Day-light rejection: -28 dB (re: 48 mW cm-1)