OBS-3A

Turbidity and Temperature Monitoring System
OBS-3A

OBS-3A

RetiredConfigurable

Turbidity and Temperature Monitoring System

Pricing

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Model:
OBS-3A
Item Number:
20921
Warranty:
1 year
Lead time:
14 days

Overview

OBS-3A Turbidity & Tempearture Monitor (Ships as 20921 & 21229)

The OBS-3A combines our OBS probe with pressure, temperature, and conductivity sensors in a battery-powered recording instrument. Batteries and electronics are contained in a housing capable of operating at depths of up to 300 meters—depending on the pressure sensor installed. (OBS® is a registered trademark of Campbell Scientific.)

Key Advantages

Accurate, Rugged
Several sensors in one probe

Technical Description

The heart of the OBS-3A monitoring system is an OBS sensor for measuring turbidity and suspended solids concentrations. This sensor detects near infrared (NIR) radiation scattered from suspended particles.

A fast-response, stainless steel-clad thermistor monitors temperature. Pressure is measured with a semiconductor piezoresistive strain gage, and conductivity is measured with a four-electrode conduction-type cell. Working depths of the pressure sensor are selected as an option. (See the Ordering Info.)

The monitor uses HydroSci software running under Windows XP, 7, and 8.

Benefits

  • Runs 1,500 to 8,000 hours on three D-cell batteries
  • Monitors sediment concentrations up to 5,000 mg/l and turbidity up to 4,000 NTUs
  • Uses the field-proven OBS® technology (U.S. Patent No. 4,841,157) to measure turbidity
  • Logs instrument depth, wave height, wave period, temperature, and salinity
  • Records 200,000 lines of data in flash memory
  • Programs set points and sampling times
  • Offers an optional 5-point sedimentation calibration

Specifications

Output
RS-232, RS-485
Maximum Submersion Depth
300 m

(984 ft)

Connector
MCBH-8-FS, wet-pluggable
Operating Temperature Range
0° to 35°C
Storage Temperature Range
-20° to +70°C
Drift over Time
< 2% per year
Drift over Temperature
0.05% per °C
Maximum Sample Size
2048
Sampling Rate
1 to 25 Hz

(when connected to a PC)

Maximum Data Rate
25 Hz

(connected to PC)

Maximum Data Rate
5 Hz

(used autonomously)

Data Capacity
8 MB
Maximum Number of Data Lines
200,000
Maximum Concentration Range
Concentration measurement range and accuracy depend on the sediment type.
Maximum Concentration Range
0.4 to 5,000 mg/L

(for mud)
Mud is defined as D50 = 20 μm.

Maximum Concentration Range
2 to 100,000 mg/L

(for sand)
Sand is defined as D50 = 250 μm.

PC Interfaces
RS-232/115 kbps, RS-485/115 kbps
Battery Capacity
18 Ahr
Maximum Battery Life
8,000 h
Infrared Wavelength
850 nm
Pressure Measurement Range
0 to 10, 20, 50, 100, or 200 m
Turbidity Measurement Range
0.4 to 4,000 NTU
Conductivity Measurement Range
0 to 65 mS/cm

(40 PSU, o/oo)

Concentration Accuracy
Concentration measurement range and accuracy depend on the sediment type.
Concentration Accuracy
2% of reading

(for mud)
Mud is defined as D50 = 20 μm.

Concentration Accuracy
3.5% of reading

(for sand)
Sand is defined as D50 = 250 μm.

Pressure Accuracy
±0.5% of f.s.

(where f.s. = 50, 100, or 200 dBar)

Turbidity Accuracy
< 2%
Temperature Accuracy
±0.5°C
Conductivity Accuracy
1%
Diameter
7.6 cm

(3.0 in.)

Height
36.2 cm

(14.3 in.)

Weight
1.5 kg

(3.4 lb) without batteries

Related Resources

Documents

Connect With Us

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Phone Numbers
General: (435) 227-9000
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Corporate Address
815 W 1800 N
Logan, UT 84321
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Email Address
sales@campbellsci.com

As a trusted leader in measurement systems for more than 50 years, our top priority at Campbell Scientific has always been to provide the most accurate, reliable data for research and industry.