James Fisher Subsea designs and manufactures containerised nitrox blenders to support the reduction of operational costs and help ensure the quality of breathing mixture supplied to divers.
Supporting increased subsea performance, the nitrox blender system utilises a Bauer nitrox blender membrane production system, which enables longer operational dive time without increased risk to diver safety.
The nitrox blender system also helps to increase productivity with a potential reduction in the required number of divers, as well as the ability to lower operational downtime with the system's capability to blend gas and refill quads offshore.
- Cost-effective on-site blending capability enabling a reduction in operational downtime
- Safe and efficient operations that are IMCA compliant, giving enhanced operational dive time with no increased risk to diver safety
- Increased productivity with the reduction in the required number of trips into the field of operations
Nitrox blender system overview
The Bauer B-TROX membrane nitrox system is capable of producing any blend of nitrox (N202) from 21% through to 40% oxygen by denitrogenating, rather than enriching standard air with high-pressure oxygen. The denitrogenated air is produced by the low pressure module which in turn feeds a high pressure module, pumping nitrox directly into a bailout cylinder or banks.
Advantages of the Bauer Nitrox blender membrane production system:
- The Bauer B-TROX nitrox system is certified by the TÜV
- IMCA D023 compliant
- The system incorporates an optimised nitrox compressor which allows for high oxygen content and temperature monitoring, to cover all stages of personnel safety
- Percentage of mix is readable on real time on the LCD oxygen analyser
- Operator does not require gas blender certification
- Allows longer dive times compared to air
- Mix accurate to one tenth of 1%
- No need for time consuming and complicated blending calculations
- Produces from 21% to 40% oxygen with continuous production
- The HP compressor part of the system can be used to fill air or nitrox tanks with no adjustments
- This is much safer to operate, eliminating all the HAZARDS related to handling 100% oxygen
- Each system is supplied with a full certification and maintenance pack
Components of the TÜV certified Bauer B-TROX equipment
Low pressure module:
The low pressure module delivers an intake pressure of approximately 10bar, which is required to supply the oxygen membrane in the Ox module. The unit housing uses effective sound insulation to ensure quiet operation.
The purification module protects the oxygen membrane inside the Ox module, giving long term operation. Contamination in the form of dust is captured by a two-stage particle filter with a filter mesh measuring 0.1μm. During catalytic conversion, the unique ETC converter splits the oil into pure water and CO2. This system allows for particularly efficient operation as there is no need to regularly change the filters, which is typical of activated carbon filters. The residual oil content is reduced regardless of oil cargo, moisture and the temperature of the compressed air. The compressed air is oil-free in accordance with Class 0 (0.0025 mg/Nm³) as per ISO 8573-1.
The oxygen membrane separates N2 out of the breathing air, thereby increasing the oxygen content. The oxygen content in the breathing air can be freely regulated between 21% and 40% (lower and upper limit values). The efficiency of the membrane is determined by temperature Therefore, to maximise the efficiency of N2/O2 separation and for constant gas composition, the air compressed upstream is temperature-controlled to a constant 20°C in a refrigeration dryer before being fed into the membrane. This ensures that the set percentage O2 content of the nitrox mixture remains constant. This system enables oxygen in the breathing air to be enriched by a maximum of 40%. The oxygen content in the breathing air is maximised when the gas is able to flow freely and without restriction; as a result, the air quantity generated by the low pressure module is maximised at the same time.
High pressure module:
In the B-TROX unit, a 4-stage compressor block is installed inside the high pressure module. This ensures that the heat produced during the process of compression is distributed across all four stages, promoting effective cooling. The star-shaped arrangement of the compressor stages optimises smooth running and increases efficiency. The free-standing cylinders are easy to access and maintain. For increased safety, the temperature is monitored by temperature sensors located directly in the gas flow and at each compressor stage. If the maximum permissible temperature specified by the TÜV is exceeded, the unit shuts down automatically and the system is ventilated.
12' x 9' containerised Nitrox blender specifications
The containerised nitrox system can be supplied in various sizes, combinations, layouts and finishes to suit any application.
|Survey authority; Det Norske Veritas (DNV)|
|Design temperature; -20°C|
|Container tested in accordance to DNV 2.7-1 requirements|
|Supplied with lifting set in accordance with BS.EN.13414-1:2003|
|Sea state 2m significant wave|
|Paint to offshore specification|
|1 x personnel door|
|2 x single container doors giving access for maintenance|
|3 x stainless steel louvre vents supplied with removable internal covers|
|Incorporates Bauer B-TROX system|
|Air ventilation system|
|3 phase, 415v power supply entering container via application inlet plug|
|All mains power supplies run internally via trunking|
|High frequency strip light with maintained emergency backup facility|
|1 x 10kva transformer with rotary isolator and rotary voltage selector switch|
|2 x externally mounted earth bosses|