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The Model 8050 pCO2 Measuring System is an autonomous analytical system for measuring carbon dioxide in oceanic surface water.
The system is modeled after instruments previously built by Craig Neill/University of Bergen.
The system may be used on a ship underway or, on a variety of at-sea platforms.
The present pCO2 system operates fully automatically and consists of:
- An equilibrator that balances the CO2 in seawater with a headspace gas that is analyzed
- An infrared analyzer (User Supplied) to quantify the CO2 concentration in the equilibrator headspace and marine air
- A network of valves and pumps that select, control, and monitor flows of seawater, equilibrator headspace, marine air, and CO2 gas standards
- An on deck enclosure that provides a GPS signal, atmospheric pressure measurement and satellite data transfer.
- An integrated notebook computer, computer interface, and software to control valves and pumps and to log data (pressures, temperatures flows, analyzer response, date, time and position).
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| Dry Box |
Wet Box |
Satellite Deck Box |
Schematic of main system components
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Overview
The system consists of three enclosures: the dry box, the wet box, and the satellite deck box.
The dry box contains a Licor CO2 analyzer (user supplied), electrically actuated valves to control the gas flow through the analyzer, a gas flow sensor, computer and interface with solid-state relays. There are inlets for up to eight gases. Each inlet has a needle valve for adjusting the flow rate. A three-way solenoid valve directs the gas exiting the analyzer towards a vent or towards the equilibrator (when analyzing the equilibrator headspace). The dry box utilizes an RS485 module and cables to communicate with the other two boxes.
The wet box contains main and vent equilibrating chambers, electrically-actuated valves, pressure gauge and regulating valve, reusable water filter, water flow sensor, barometer, temperature probe, condenser unit , two Naphion drying tubes, and three air pumps. After entering the wet box, seawater passes through the reusable filter, which can be automatically back-flushed with fresh water. An adjustable regulating valve after the filter sets the water pressure that is delivered to the equilibrators. The vent equilibrator keeps the CO2 concentration in gas that exchanges with the vent on the main equilibrator close to the concentration in the main headspace. The barometer and temperature probe are attached to the main equilibrator. Seawater drains by gravity out of the wet box.
One of the air pumps in the wet box pulls the headspace gas from the main equilibrator and pushes it through the condenser, a Naphion drying tube and then the CO2 analyzer. Another pump pulls air from an exterior inlet provided and located by the user and pushes the air through a condenser. After the condenser, this gas stream is split towards a vented chamber and towards a drying tube and then the CO2 analyzer. The reduced-humidity air in the vented chamber is pulled through the drying tubes as counter-flow gas by the third air pump.
The weather resistant satellite deck box contains the modem for Iridium satellite communication, a high-precision barometer, a power supply, and data communication modules. A GPS transducer is attached to deck box and data modules. A ten-conductor cable connects the deck box to the dry box (a 25 meter cable is provided; a cable can be up to 1000 meters long, an extra connector is provided for making a cable for a permanent installation). There is a bulkhead tube fitting for connecting a Gill pressure port to the barometer (pressure port not provided).
Options
The following options are available for the 8050 pCO2 Measuring System.
Model I8050-7
Idronaut 7 Parameter Sensor Module
The Model I8050-7 Idronaut 7 Parameter Sensor Module is a high quality fast response in line water flow marine instrument, designed to be integrated in the wet box of the pCO2 system. The instrument offers a combination of 16 bit high resolution data accuracy with long term sensor stability. The instrument can accommodate up to 7 of the sensors found below.
Pump Option
General Oceanics is able to recommend or supply the proper seawater intake pump that best suits your needs. Please contact us for further information.
Through Hull Water Intake Plumbing Option
This package is a Lloyd’s approved below water line module, self contained with all exposed parts either stainless steel or plastic. The unit includes a guillotine shut off valve in case of catastrophic failure. The unit collects water a few inches from the hull through the intake pod assembly. Options include an external sea surface temperature sensor, and a chlorine gas generator to eliminate growth of any microorganisms.
Specifications
Model 8050:
Wet Box: Length 24 inch (61 cm) Width 24 inch (61 cm) Depth 10 inch (25.4 cm)
Dry Box: Length 24 inch (61 cm) Width 24 inch (61 cm) Depth 10 inch (25.4 cm)
Satellite Box: Length 14 inch (35.6cm) Width 10.5 inch (26.7cm) Depth 8 inch (20.4cm)
Note: The User must supply the following items:
1) Main water intake pump and plumbing (interfaces to the wet box), see pump and through hull intake plumbing option above.
2) Calibration gases and connecting lines.
3) Co2 analyzer (Licor 6262 or 7000 recommended)
