BAUER Junior II-B (petrol) Breathing Air Quality: EN 12021, CGA Grade E and NFPA Testing Guide
Air quality is the reason a breathing-air compressor exists. This guide explains how to build a defensible testing programme around a BAUER Junior II-B (petrol): which standards apply, what each parameter's failure tells you about the machine, how often to sample, and how to document it.
1. Equipment overview
The BAUER Junior II-B (petrol) delivers about 100 L/min (3.5 cfm) at up to up to 330 bar, driven by petrol engine (Honda-type industrial engine), and is typically used for mobile refill vehicles, remote dive sites, emergency response without mains power. It is a petrol-driven field unit, engine speed directly influences output, which influences how often the filtration system needs attention.
| Parameter | Typical specification |
|---|---|
| Free air delivery | about 100 L/min (3.5 cfm) |
| Maximum working pressure | up to 330 bar |
| Drive | petrol engine (Honda-type industrial engine) |
| Filtration | P21 filter cartridge system |
| Typical applications | mobile refill vehicles, remote dive sites, emergency response without mains power |
These values are typical market configurations. Confirm every value against the data plate and the manual of the individual unit before ordering parts or planning service.
2. The standards that matter
- EN 12021 - the European reference for breathing air, covering CO, CO2, oil, water and odour;
- CGA Grade E - the common North American specification for compressed air for breathing;
- NFPA 1989 - referenced by many fire-service programmes for breathing air quality and filling operations;
- Local occupational or diving authority requirements, which may be stricter than any of the above.
Always test against the edition and standard that applies at your site, and confirm the limits with your testing laboratory rather than with any secondary source.
3. Parameter limits and what a failure means
Breathing air is a life-safety product. In the EU the reference standard is EN 12021 (current edition), and in North America diving applications commonly reference CGA Grade E, while fire-service programmes often reference NFPA 1989 for breathing-air quality and filling operations. Limits differ between standards and editions, so always test against the edition in force at your site.
| Parameter | Indicative limit / requirement | What a failure usually points to |
|---|---|---|
| Carbon monoxide (CO) | Typical EN 12021 limit: max 5 ml/m3 (5 ppm) | Rising CO usually indicates intake contamination or overheated lubricant - check intake siting and stage temperatures |
| Carbon dioxide (CO2) | Typical EN 12021 limit: max 500 ml/m3 (500 ppm) | Elevated CO2 often traces to intake air drawn from a confined, occupied or engine-exhaust-affected area |
| Oil (lubricant mist) | Typical EN 12021 limit: max 0.5 mg/m3 | Oil carry-over points to separator, drain routine or a saturated cartridge |
| Water / humidity | Pressure dew point requirement to keep cylinders free of liquid water | Verify dryer performance, drain routine and cartridge condition |
| Odour and taste | No objectionable odour | Any detectable odour means stop using the gas and re-test before release |
A practical programme is: test every production batch or at the interval required by your authority, keep a written record of results, replace the filter cartridge by hours and by test result (whichever comes first), and re-test after any intervention on the filtration system. A BAUER Junior II-B (petrol) that passes its air test but shows a rising trend is telling you the cartridge or the intake environment needs attention before it fails a limit.
4. Faults that degrade air quality on this machine
| Symptom | Likely cause | How to confirm | Corrective action |
|---|---|---|---|
| Delivery falls short even though engine sounds normal | Engine speed below governed RPM or slipping drive belt | Measure engine RPM under load and check belt tension | Restore governor setting, replace or tension belt |
| Engine stalls when the compressor loads | Load applied before warm-up or carburettor mixture issue | Warm up and observe load behaviour | Service carburettor, adjust idle, verify load sequence |
| Exhaust smell traced to the inlet | Intake scoop positioned downwind of the engine exhaust | Observe inlet placement relative to exhaust | Relocate intake to clean upwind position, re-test air |
| Hard starting after storage | Stale fuel or fouled spark plug | Inspect fuel age, plug condition | Drain fuel, fit new plug, run to operating temperature |
5. Sampling and documentation
- Sample at the point of use, not at the machine outlet only, and use a sampling method accepted by your laboratory.
- Set frequency by regulation, by throughput and by risk - batch testing is common for filling stations.
- Record result, date, operating hours since the last cartridge change, ambient conditions and the cartridge batch.
- Define an action level below the limit, so you investigate a rising trend before a result fails.
- Re-test after any filter, separator, valve or intake work, and after any overheating event.
6. Service scope
BAOSI / DEJUE (Shanghai) supplies high-pressure breathing-air compressors and also supports third-party service and consumables for mixed fleets. For the BAUER Junior II-B (petrol) and comparable units we can supply compatible filter cartridges, valve plate kits, belts, lubricants and seals, and provide troubleshooting support, overhaul guidance and annual maintenance planning. Where a brand-specific part number is required, we match it from your serial number and filter housing type.
Need parts or a second opinion on a fault? Send the model, serial number, operating hours and the recorded stage pressures or temperatures - our technical team will respond with a parts list and a diagnostic plan. Contact the BAOSI technical team.
Disclaimer: This article is provided for general reference only. Specifications vary by serial number, build year and market configuration - always verify against the original equipment manufacturer's manual and your unit's data plate before service. Work on high-pressure equipment should be performed by qualified, trained technicians, and any safety-critical repair should follow local regulations and the OEM procedure.