K14 Elevated CO2

[Tassi Devil Diver]

Hey, I have a Bauer K14, ex dive shop compressor built in 1995 has a little under 5k hrs. I have had it 13 years, and do about 15-20hrs a year, not much use, mostly filling cylinders to run a thirsty booster, topping off bailouts and dil for my rebreather, a few air fills now that my daughter is diving.

With my daughter now diving thought I would get the air tested for peace of mind. First test came back failed due to high moisture, unexpected, they suggested I submit another sample, emptying the tank slowly and filling opening the condensate dumps more often. Second test failed, moisture was fine this time failed CO2, suggested I submit another sample this time run the compressor for 10min before filling tank for sample. Third test passed though moisture and carbon dioxide content were close to the maximum acceptable limits.

Any suggestions as to what might be going on here? The filter cartridge has around 10hrs on it.

How do compressors concentrate CO2? curious to know what is going on here. The compressor is kept in open garage with air intake outside, so not concentrating CO2 from elevated level in the environment. The Bauer service teck at my LCD suggested that compressors can periodically dump CO2, suggesting running the compressor for 10min before filling and fill into a bank so any CO2 dump is diluted.

 

[Agro]

So it seems, the K12 itself produces CO2. Never heard about that.

Are you 100% sure air intake is not in a high-CO2 area? Any exhaust around? Industrial production in the neighbourhood?

As far as I know filter does not eliminate CO2.

 

[Tanks A Lot]

This is a bit tricky to answer without knowing all the parameters, but here are a few things that might help.

• Ambient carbon dioxide (CO₂) levels currently hover around 430 ppm. In large industrial cities, however, concentrations can easily climb to 1,000 ppm or higher. That’s already double the limit for compressed breathing air, which is capped at 500 ppm under standards like EN12021:2014.
• A compressor can also introduce carbon monoxide (CO) into the system, especially oil-lubricated models like the K14. This typically happens when some of the lubricating oil begins to "burn" due to excessive friction, often caused by worn or damaged parts. Depending on your filter cartridge, it may contain Hopcalite, a catalyst that converts the toxic CO into CO₂. While this reduces CO, it can further elevate CO₂ levels in the breathing air.

Even with everything working properly, your location alone might be contributing to high CO₂ levels. I suspect that in the future, dive shops everywhere will need equipment like the Bauer Aeroguard to stay within spec. Alternatively, the standards may be revised. But either way, it's a growing issue that needs addressing.

The fact that you failed the moisture test is also not nothing. The current moisture limit is around 35mg/m³ for pressures above 200 bar, which is usually quite achievable. Your filter has only 10 hours on it, but keep in mind that most of the water is removed before it even reaches the filter. It's possible there’s a minor issue with one of the cyclone separators, or perhaps the PMV isn’t functioning as it should. I’d recommend removing the valve and taking a peak inside your cylinders.

 

[Capt Jim Wyatt]

Is the compressor inside or outside?

 

[rhwestfall]

Great comments above.

Also, at 10 hours, your filter may be "done", an/or the moisture may have gotten to the filter...

@rob.mwpropane might be able to post my filter life spreadsheet (I don't have easy access to it right now).

 

[Wookie]

I agree with everything Tanksalot said, and want to add that one problem with a K-14 is that it probably has a tall tower on it. The filter is good for 25 hours or 3 months. If you’re putting 10-20 hours a year on it it likely has time to leak down between uses, and nothing kills a filter faster than sitting at ambient pressure.

 

[Miyaru]

or perhaps the PMV isn’t functioning as it should

My thought as well.

To the OP: start the compressor and keep looking at the pressure gauge after the last filter.
If it gradually increases pressure, it's not good.
It should stay near 0 and then suddenly climb to ~130bar once the compressor has been running for a few minutes.

 

[rob.mwpropane]

Great comments above.

Also, at 10 hours, your filter may be "done", an/or the moisture may have gotten to the filter...

@rob.mwpropane might be able to post my filter life spreadsheet (I don't have easy access to it right now).

Here you go!

 

[rhwestfall]

The spreadsheet uses the data from Bauer that adjusts the filter use based on ambient temperature. I curve fit their data to an equation. You will be surprised how much filter life decreases with elevated temperatures ..

 

[grantmac]

If you weren't diligent with dumping condensate and a bit of liquid water hit the filter that can cause issues like channeling.
Weird that it was CO2 rather than CO. Try relocating inlet?